I realize this video is a few years old, but I'm glad I found it. I wasn't having a problem, I'm just kind of consumed with watching diagnostic videos to learn even though I've retired from a different field. This is what I do instead of watching tv. Anyway what I wanted to say is that watching you step through this made me see that you never strayed from your strategy of teaching investigation over parts changing. So many times when you or Eric O. or Scanner Danner and others head down what looks like a wrong path you find a problem by being on that path. That is the big lesson. Besides learning, it's really enjoyable watching you succeed. Thanks again.
Thank you for letting us learn with you. I really appreciate that you keep in all of the highs/lows successes and let-downs. Its good to see that. Many videos edit out those more frustrating portions, which cuts out a lot of learning opportunities for the audience.
Excellent video. As a shop owner I'd hire this guy in a heartbeat, understanding how something works and how to use your resources is the key to correctly diagnosing and repairing. Nice job
Anytime you EVER EVER EVER have a long crank time one of the first steps should be checking fuel pressure. This video is gold Matt, diagnostically golden. Kind of sad that a dealership technician couldn't fix these issues but on the other hand it validates your skills as a DIY technician and the purchase of the oscope. Congratulations on a superb and vindicating video. Bravo. To those that think he missed the issue of the no-start like he completely whiffed on the diagnosis, he in fact did not. He 100% fixed 1 of 2 issues and confirmed 2 major separate issues. The crank sensor would have eventually completely failed and left the owner stranded, just a matter of time. I hope we get to see a Part 3 where you trace back the culprit of the bleed down and fix it!
+DJDevon3 When most cars have a loss of cam or crank signal you will also have a long, long crank time. Try unplugging the crank on a VW- it will have a long cvrank time.
Schrodingers Box Most DIY'ers don't have scopes so the first thing i would break out is a fuel pressure tester. I'm in no way implying that you did anything wrong diagnostically. In fact you did a superb job, certainly better than I could have done. It's why I'm a subscriber. ;)
This is one of those times where there was more than one problem, even if it wasn't apparent at the time. When there are multiple faults, you have to fix the most "obvious" first before any other faults become obvious, and can be tracked down.
You did great Matt, I have encountered driveability issues on Buses where I have found multiple problems cause the main problem. Because of this one of the first things I do on a driveability issue is I do a battery,starting,charging system test because if these components are not working right, nothing else will.
Those crank sensors are adjustable. You'll notice that the bolt sits in a slot. Shop manual says to use a tab that is available and stick it on the end of the sensor. The tab is a small piece of cardboard about the thickness of a business card with sticky on it. With the tab on the end of the sensor push the sensor in till it sits on the relucter ring part of the flywheel then tighten the bolt. Using a peice of business card with a spot of grease works good. The tab or business card is thrown out when the engine is started. If the sensor is too deep it will scrape the flywheel, and if the sensor is too high it wont run. If the sensor is slightly too high it could work then quit later. (seen it several times, cuz I was in transmission industry for 26 year and we pulled hundreds of those transmissions with crank sensors passing through them.
+CoolAirVw Yes that part I knew... however along those lines, since the video I have done some research and also noticed that the cam sensor was clearly installed incorrectly by the previous shop and in fact I did not set the sync correctly with my scan tool either. Currently the vehicle is almost 20 degrees off with the cam signal. When I get the vehicle back this will be adjusted correctly.
Another awesome diagnosis video! If after all this, you don't end up hating Jeeps and can gradually become an "expert" on them, you will be a global hero to all us Jeep owners. Online forums are jam packed with Jeeps suffering from random stalling/no start issues (experiencing this myself right now), with members offering countless solutions that are all over the board. So with this Grand Cherokee you're working on, I myself am anxious to see you resolve it for the owner. Thanks again Matt - you rock!
+Steve C This is really not the jeep's fault. The code was absolutely correct (though would have been nice if it differentiated cam and crank instead of combining them. The starting problem is obviously a bad check valve. But since there is no pressure sensor on the rail, the jeep cannot possibly "know" this and with normal fuel pressure when engine is running and normal fuel trims, the fact is- the jeep PCM made the right call with the cam/crank code being the only code.
Matt thanks for showing this video .I learned loads from this and will keep in mind that sometimes you can just focus on a certain point from the scan tool code and that more than one fault could be a possibility .Great that you found the issues.At the end of the day your logic came through and you did not throw hundreds of dollars at it.
….. so I’ve been dealing with a P1391 code on my 04 Rubicon for about 3 months an I’m about 90% sure you just showed me the issue, I’ve replaced my OPDA, IAC, MAF, TPS, all 4 02 sensors and all 6 spark plugs trying to fix my issue. Really thought I had in about a week ago by unhooking the battery draining the system an making my computer basically do a reboot. I don’t have a starting issue but a very intermittent miss fire with no miss fire codes. I subscribed and liked your video. If the CPS ends up being my issue as well I’ll let you know but thanks for a very informative video.
I think your mistake was believing that you had fuel when the "NOID" type light was flashing. That flashing only tells you that you had control signal to the fuel injector. By no means did it provide an indication that there was pressure in the fuel rail to go through the injector to the cylinder. You got it though. Good job!!
I don't see that as a mistake. He needed to see if the computer was telling the injector to fire. There was a problem with the crank position sensor. Just needed follow-through with measuring rail pressure, especially since it had a history of failure. You can't go down two paths at once.
You will always run across something you do not know so you just fall back on the scientific method. Systematically rule out what it is not, until you find out what it is. Great demonstration of that procedure.
Actually IMO seeing someone bark up the wrong three is by far more useful than watching another "hey, watch me fix this loose wire or replace that fuel pressure valve" video. This debugging is where I spend 80% of my hobby shop time. Thanks for taking the time to record and edit and hope for more problems in the future ;-)
+Dawid Ciecierski Absolutely true! In fact, better to use an illogical approach but still test everything along the way than to just parts change in fact. But this is precisely how I learned everything I know- it's the trial and error that does it. And the research I am forced to do too.
OMG, I finally got one right! I'm no cam/crank expert but in PT.1 I was thinking of fuel pressure when the light went off, I was thinking that the fuel relay may have a timer or something in it that kills fuel if the engine hasn't started in X seconds. I thought for sure you were gonna check fuel pressure right then, because you alluded to fuel pump issues in the past. Great Vid, that's why I watch, I been learnt something today.
+Jason Beattie Yes but there was no logical reason to expect fuel pressure based on the fuel trim indications from the freeze frame data, wouldn't you agree?
+Schrodingers Box You need FAST (or something like that!), right? You did not follow your own procedure to diagnosis a no start condition. I can't believe you are still making excuses.
100 incorrect. I did follow fasttec procedure- the evidence based on timing advance, fuel trims and the code indicated to triage the ignition timing. Why would you think Fuel pressure FIRST when you have recurrent 0189 when cranking and lift at zero with no STFT adjustment and 50 degrees advance???? please explain your rationale.
Matt, I'm currently a reformed 98%er so, fuel trim and freeze frame do not yet enter my thought process in regards to fuel pumps.. This is why i watch your videos because misdiagnosis is the bane of my existence. I, like you, cover parts that I misdiagnosed. These are cars that we work on not space shuttles, with the right understanding and correct information, part changing shouldn't ever happen. Keep up the great work!
Jason Beattie Well if variables and data are not included because they are not understood, that certainly will narrow down the troubleshooting chart.... but due to what is known as "false dichotemy logic fallacy"
When reinstalling the crank position sensor, there is a paper decal that can be purchased from jeep to properly set its depth. The paper decal will rest on the flex plate and will be torn off when the engine starts. If ithe crank sensor is installed too deeply it will be destroyed by the flexplate. This also needs to be reset any time the transmission is separated from the engine, because the sensor is on the transmission bell housing and the flexplate is attached to the crank. Reprogramming of the crank position sensor should only be needed if the 'oil pump drive gear' that the cam position sensor sits on had been tampered with. This is noticeable at high engine RPM under load when precise timing become more important. It also controls injection timing so there would be issues there at higher RPM's as well. Not mentioned in this video setting the the cam position sensor with the toothpick just gets it in the ballpark, needs to be finished with a commercial grade OBDII scan tool.
Ok so I’ve swapped the OPDA in my 2004 Rubicon. I’ve had it hooked up to a couple Newer Snapon scanners an according to the scanners it runs great around -30 with the timing. If I get it locked down around 0 it idles great but face plants with any amount of gas… really thinking I need to take a look at my Crank Position Sensor as I have had my trans out and back in multiple times in the last year or so. Replaced the sensor once but not in the last couple times that I’ve dropped the trans.
@@PureToxicYouth At -28° I would intermittently loose spark at higher RPM's and sometimes have to re-start the engine when one of the coil packs would just stop firing. Now at 0° no issues. Are you sure you are at TDC with the toothpick installed in the CKP?
@@markcarpenter3600 unfortunately my OPDA didn’t come with the holes to do the toolpick trick but it came with a plastic retainer to hold it in position when installing it. I’m about 90% sure I was TDC on the #1 cylinder when I installed it.
I would say that getting vehicle history is important and that even a professional tech can really screw the pooch....in addition I would say that unless some symptom is very obvious checking the main three contributions to combustion should be put on the table in most applications. good set of videos Matt, well done.
Hey guy, I enjoy your videos and approach to troubleshooting, everyone can learn a bit from you and re-think their approach to troubleshooting, be it good or bad, and i appreciate your efforts. I link your videos to a lot of folks to learn and disagree as well. Just a heads up, i had a vehicle with damn near all of these symptoms same codes and odd drive-ability concerns - an intermittent transmission starting in second gear, In my case, it was a bad harness connector on the firewall. I am not sure how common that is, but it ran me in circles until i figured that out. In my case,The wires deliberately pulled tight like in your video were a clue. Also something to consider on some Chrysler engines, if you yank the cam sensor and it cranks, you have a usually have a timing issue, the two signals are fighting each other in the pcm if they are not in sync, it wont crank. You unplug one, and vroom + code. I assume it is a safety thing to save your engine if it is of interference design. if the engine has a timing belt, its probably off a tooth off or so. if it has a timing chain, most likely a failing tensioner/guide/sloppy chain.
LOL, I have a 97 Wrangler that has always needed a 5 second crank/stop/ crank in order to start. I just figured it was a quirk I had to live with. The first crank could be 30 seconds and it wouldn't start but a brief initial crank and it would start and run fine. I didn't watch this video for that information though. Just purchased an 01 GC and needed some info based on the topic of the vid...learned two things in this one vid.
In this case I would try to prime the fuel pump multiple times WITHOUT cranking to build fuel pressure, then should be more likely to start when you crank it
Its all about the struggle....Its just more fun when your the one struggling :)Im guessing the Starter will be the next Item to go...............Nice video Matt.
+Charles Miller I talked about how much more fun it is for another to struggle video 1 too, lol. Sorry Matt, but when there's struggle we think the hardest. I'm thinking starter next too! lol
The crank sensor has a felt pad on it . Its a one shot deal... once the felt gets ripped off after thr car starts YOU CAN NOT LOOSEN THE BOLT or it will rub on the flywheel and toast the sensor .. for being the bolt was loose i guaranty the felt got torn off and the sensor is rubbing on the flywheel causing the issue to the fuel pump , jeeps are tough to diagnose... i have 5 of them .been there done that. I have seen it all with these things...good vid 👍
that made me laugh after i read the disagreement between you and the other guy on your last video that said you should check fuel pressure as soon as you saw you had spark and injector pulse. lol
+lolz larkin Lol he was right but for the wrong reason, I was trying to get him to see that. But yes I already knew the whole time he guessed right. But he obviously didnt watch the video so he thought this was just a cranking no start diagnosis. In that case he woulod have been 100% correct
Well I think you were secretly hoping it was a ckp/cmp sensor problem because it would be perfect for the channel. You'd be surprised at the amount of people I've seen chasing their tails looking for something complex and it turns out there's no fuel in the tank, or there's an e-stop pressed somewhere they forgot to check.
lolz larkin Well there was a crank sensor problem of course but yeah, not the one I was hoping for- I was hoping for an intermittently grounded signal or 5V wire or something lol... but glad that thing is out of here- I got sick of looking at it and it took my whole saturday!!
+White Tiger This was a great one!! Having two completely unlinked problems that share the same symptom indicated by a single check engine code created a "logic loop" that sent me up the wrong branch as a direct result of my logical process!! Someone who didnt know anything about cam, crank, fuel trims, or timing would have solved the cranking problem much faster for sure. life isnt fair lol!!
Set sync signal is a great tool. I had your same p1391. Dtc on a 98 Cherokee my self and the guy b4 me threw a cam sensor and shaft at it. I had to use sync signal to see he installed shaft off time by some amount of degrees. I retired engine and dtc went away. You would then use set sync signal and turn cam shaft sensor shaft till with in specs/proper degree (ignition timing)
Great job Matt. Good not to stay so focused on one thing and overlook other options along the way. On my VW, the car works fine on crank sensor only but has a long start. The car will not work on cam only and stalls when loses crank sensor. The cam sensor is used by the computer to find TDC of cylinder 1 for much quicker starting.
I remember there was a youtuber (the channel name has a picture of pussycat and some unknown scientist) who presented a great video about how to methodically diagnosis a no-start condition; he even had an acronym (FAST or something like that) for it; may be you should watch it? :-) You do deserve all the bricks that you are (or should be) getting for this one! I mean when I saw spark and injector firing, I am yelling from my keyboard "check the fuel, Matt!"
+12vgs8606 I did follow fasttec- the evidence overwhelmingly indicated timing as the top of the triage and in fact, based on the fuel trims and timing advance, fuel pressure was actually CONTRAINDICATED.
Shall we look at the evidence here? The car came in with hard start, perceptible misfire during running, code indicating cam or crank signal failure. 1) visual inspection showed loose crank sensor 2) noid light and spark plug tester proved injector pulses and spark control from ECM 3) the hard start particulars:- when the car eventually starts, it runs great i.e. there is no rough running for a second or two after the car starts. Just this clue alone will tell you that it was not getting the fuel when it was not starting because if it was missing the spark, and if the spark eventually started firing, the engine will start but it will be coughing until it burns the excess gasoline. 4) the engine has timing chain; so highly unlikely it was slipped; besides both actual spark and fuel control were observed; if the timing was way off, you would have whole bunch of backfire. 5) "I have no time" was mentioned too many times in the video 6) There is absolutely no way that you have provided any justification for not checking the actual fuel once you had spark and injectors were firing. With 99.99% certainty, you should have known fuel was not getting to the cylinder. Heck, I probably have less than 10% of your knowledge and skills but many clues were present in this situation to know that most likely cause was no fuel. It is irrelevant what the freeze frame data or the fuel trims were on that engine. I am disappointed that your ego is not allowing you to accept the fact t
Timing as a probability was dismissed because the engine behavior when it did start did not indicate timing issue. One has to take in to account *all* of the evidence. Apparently, you are the one who is ignoring some of it.
hi mat the reason i said the fuel filter regulator is because the fuel system you are working on is not a returnless fuel system the fuel filter regulator has three lines inlet outlet and return that means the fuel regulator must also have a check valve (source all data fuel is supplied to the filter regulator by the electronic fuel pump the regulator acts as a check valve to maintain some fuel pressure when the engine is not operating this will help start the engine a second check valve is located at the end of the electric fuel pump )
+anita brodie Hmmmmm I was pretty sure the regulator is in the filter but check valve is surely on the pump outlet. I will have to check on it- Ha, check on it- get it?
Great video and entertaining.Making assumptions can be hazardous.A thorough background understanding on the complete engine operation is a priority but can be very time consuming with so many variations out there.
+Tom OConnor Yeah I ran into a real conundrum here... like you said there are sooooooooo many variations and the research would have been literally hours. I only had 6 hours with this truck and filming triples my time so I was in a huge rush. It was simply impossible for me to do the research I needed to do and yes, I had to make assumptions of the functions of the sensors some of which obviously turned out to be wrong. This is a definite case where more research than wrenching is needed.... how many people in the whole world are willing to do that? So far I only know of about 30,000 lol.
Great video ,thank you for what I have learned from you .I love whatching your videos over and over again .I am better in my job ,I work in an auto shop ,thank you.
+Carlos Dorantes Awesome of you to say that man. Most people that work at shops wouldnt admit they can learn from a DIY. But I learn from you guys too- my favorite subs are professional mechanics. They really make the channel what it is.
Awesome video Matt, since no two mfgs do things the same way. Dealer tech gets to go to school every time something new comes out. We are not so fortunate so working on different brands can be challenging. you did an excellent job of narrowing it down . Excellent work. Thanks
Thinking some more, the pump seems to run perfectly once it is operating. Could this be something like a relay or regulator/check valve problem? Because once the car was running and the ckp was correctly fitted, it didn't miss a beat. So it's not holding pressure without the pump running. Close?
+Mathew Wood exactly correct again bro. Damn kid- you got it down!! Yes a bad fuel pump check valve is almost certainly the issue. A relay problem explains the hard starting too, but not the immediate drop in pressure to dead zero when engine stops. A check valve explains both though. Of course- after this video it could be a bad relay AND a bad check valve lol!!!
Thanks Matt. I'm starting to think more about my conclusions before I actually go ahead and start repairs, thanks to your explanations and tutorials. I really appreciate your work, thanks.
Almost instantaneous pressure rise during extended cranking preceding startup suggests power is being interupted to the fuel pump. Perhaps main fuel relay or wiring issue. Check valve may not be a factor. Great video. Easy to get fixated on one aspect of a problem and forget basics. regards
+ksauto1 Lol- it is sometimes very tempting to just say "aw hell throw a MAF at it" but if I am wrong, I have to pay for it out of my own pocket. Plus also can you imagine the backlashing I'd get if I just gave up halfway through and guessed at a part!!!
MATT, HELLO I am a little late writing this but what a great info and process of thinking to approach this kind of a problem even some professional techs could not know how to do just want to say big thanks to all the knowledge that you share and waiting to watch the part # 3 i hope cheeeers my friend .
I'm having the same problem on 1999 jeep with p1391 having problems cranking and running, the fuel problem could also be my problem? I replaced the cam censor a while back seem to fix the problem but recently started back, could changing the cam censor compensated for the fuel problem if have one, I'm going to check the fuel problem tomorrow
depends. what was the data you got that indicated the cam sensor was at fault? Was a bypass done? what were your reference and power inputs and how was ground verified?
If you think about it the only time the control unit needs to know the cam position is at start up and then only +/- 180 degrees. Spark timing is probably determined by the flywheel sensor with many more teeth (higher resolution). You also need to find out the sample rate of your scope and compare that to the frequency of the signal you are looking at.
+Richard J Lebens Hmmmm good point, I never considered that- makes perfect sense. Totally explains no start when can sensor disconnected but no effect when engine running and its disconnected.
+Richard J Lebens Even the slowest scope in the world is going to be more than fast enough to watch cam sensor signals and crank sensor signals. Your point about the crank sensor signal having higher resolution is interesting.
+douglas lee I was pointing out the relative fundamental frequencies of the signals. The cam sensor was 6 Hz (15 running) and the Crank sensor would be (150 (?) flywheel teeth/rev x 900 rev/min * 1/60 min/sec =) 2250 Hz. (Did I do that right?) Usually on a digital scope when you turn the time base down the sample rate matches the display resolution. I did not look up the specs on that scope. The ECU also has to know precisely crankshaft TDC. I wonder if that was some of the crank signal weirdness.
+Richard J Lebens Richard, I'm not sure if I'm totally following you, but I think I sorta do. The main point you're making is that the signal in question would be around 2250 hz, right? Well, that's nothing for any scope, whether digital or analog. By adjusting the time base knobs or buttons, the operator will be able to put the scope in the correct "speed range", and then the auto trigger (or a manually set trigger point) will take care of the rest.
+douglas lee That is true. I was concerned with aliasing and not bandwidth. I was trying to point out you couldn't look at a real slow signal and a real fast one on the same screen without verifying the sample rate was sufficient to capture a reasonable representation of the faster signal. I should have put that in the first post.
At the start of part one you mentioned that fuel pump problem and I thought then that perhaps it could be the issue but , like you, I didn't give it another thought until you went back to it. Good find, Matt and thanks for another great video.
Yes the evidence seemed pretty overwhelming for only the cam crank problem causing everything. What hooked me was if you cleared the check engine codes the code came right back on just from cranking- obviously this was because vibration from the cranking was wiggling the sensor but it sure seemed like it was because the cam or crank was causing the hard start.
Good job on both the video and the car --- I wasn't expecting the fuel pump Issue to be the cause of the non-starting. The case well illustrates the value of a scope for checking crank, cam sensors and also applies to wheel sensors. I have had run-ins with cam and crank sensor my self and now wouldn't be without scope, I mainly work on the same type of engines ans so have made breakout connectors from scrapyard and cast off parts to allow quick connection. The cheaper USB or palm sized scopes are now well within the DIY mechanics price range under 100/£70/100 Euro.
Good of you to mention that there MAY have been a better diagnosis path you COULD have taken....like you said hindsight is a wonderful thing. Take the crank sensor issue though...it needed sorting, so in fact there was no wasted time at all. And often in diagnosis, knowing what is right...verified right...leads to finding out what MUST be wrong, which can then be verified. Good 2 part video, enjoyed it...thanks.
+Ian Muggeridge Yea you totally get it. A better diagnosis path would have involved understanding of the responsibility of the cam and crank sensors for this specific model. It would have allowed me to much quicker dismiss that the cam signal was indeed being used by the PCM and I would have abandoned my initial strategy of leveraging the hard start as a diagnostic strategy
Matt! Wow that was a good one! Totally agree about the blindfolds...we have a code, so that is the problem right? With most cam-crank codes, my weapon of choice is a scope (you already have that covered :) and a reliable wiring diagram. Check out the free BBB Industries database...only takes a few seconds to pull up the correct manufacturer diagram with wiring colors and connector pins. So why the heck does that Jeep eat fuel pumps for breakfast?? Wouldn't be surprised if the starter takes a crap soon too...looking forward to the next Jeep vid!
+motoYam82 Yeah this was a good example of how a logical approach can actually take longer than guessing lol. I should have jeep next week and I will diagnose it for sure
+Schrodingers Box True, but the "logical approach" only takes longer on the initial learning curve...like you said doing the research on these systems that vary by manufacturer takes a lot of time. Looking up a diagram and hooking up the scope is usually the fast and fun part :) Guessing/swaptronics on the other hand might initially take less time, but there is no learning curve at all haha. I'm surprised that the Jeep owner agreed to pay for all those unnecessary parts before bringing it to you!
motoYam82 Well its hard to earn credibility when you're not a mechanic and you do this stuff out of your home garage in a residential neighborhood. But I definitely earned his respect after this one lol
Yup, got tunnel vision on a Saturn L300 thinking it was a fuel delivery problem after running 10 minutes and die. Started thinking after the vehicle would start then die after 10 minutes of running, I was looking at something else. Sure enough cam sensor would show open when I ohm'd it. Great vid!!
+Schrodingers Box Didn't have CEL. Went on Saturn forum (don't judge, was pressed for time😏) after heating up, sensor showed open, replaced it, no issues since.
+John Kobberstad Matt didn't make a mistake with reading the noid light, as the fuel trims showed no issue. Why would he be look for something that is not indicating a fault? The fault indicated a cam sensor issue, so the noid was used to check for a cam signal, yes?
+Mathew Wood DING DING DING WE HAVE A WINNER!!! Exactly correct bro. The thing is most of the people who think I made a mistake not checking fuel pressure are ones who don't understand interpreting fuel trim and timing data. If you dismiss the codes, fuel trims, and advanced timing from the freeze frame data because you don't understand it, then yes, you would check fuel pressure as a next step.
Schrodingers Box yeah, it's an illogical conclusion to say you misread the noid light. Also, how many of these genius parts changers would have changed the pump, the filter, maybe even injectors before getting to the actual cause?
Mathew Wood in all honesty, for my viewers, very few of them i bet, actually. Its more a matter of understanding the logical process here, but they would still not have guessed on parts I am sure
Mathew Wood Oh in that case for sure bro... for sure. I would be shocked to see otherwise.... actually I never have. Every car I ever see that was seen before me had at least one thing changed... usually more like 7
this video helped me with the same code i had with a jeep nd it ended up.being that the camshaft was loose tightend the bold.eared the codes nd nothing came back thanks for the help
Haha. That's awesome. At part 1 I thought: i don't know, but the no start will not be related to crank/cam for sure. In some video from past you said that with nostart condition you always do a few basic things like spark, fuel, timing etc. I set this as my golden rule and it works 100%. Ofc I understand why you run into all this problem here... But just keep using your own rules bro :) Excelent videos, excelent case, great as always actually. You are still my favourite diagnosis guru Matt. The only thing that bothers me is you mentioning the time. A few times. Its a little bit anoying to watch you being in hurry. Especially with such an interesting case. I'm pretty sure you can just edit the video without mentioning you are in hurry and it would be way more fun to watch. Other than that - looking forward to the next one!
+Schrodingers Box It was not completely clear from the beginning that there are intermittent misfires so I was not really worried about that. I only knew the car history from previous videos (yeah, you had pretty hard time already before with diagnosing fuel pump), the symptom (intermittent nostart condition) and check codes. I don't work too much with scanner tools (mostly because I work with older vehicles) so my focus would definitely go in direction of fuel delivery first (and actually you did this test with the bulb attached to injector, but you've only checked if injector is managed by computer, not if the fuel goes into cylinder...), then ignition (and you've checked that), then timing... Actually after you did a test with spark tester and fuel injector bulb - it was pretty clear it's not crank/cam and it needs to be related to fuel and/or timing. Probably after that I'd experience misfires so this would be next in my list and this diagnosis was really great in your video! Maybe it's just because I'm less scanner-scope-electronic oriented guy and more mechanical oriented one. And that's why I'm here to learn this scanner-scope-electronic stuff from you ;)
Matt, great fix! Again, and I know you were pressed for time, but if you scoped your cam and crank signals after the fix you would of definitely looked in the direction ( fuel ) that you did because of the cars history and symptoms. You also just proved how smart them PCMs are when you unplugged the cam sensor as it was able to calculate the cam/valve position for injector timing based on crankshaft position.
+Billy R Yeah but what really threw me is why unplugging the crank didn't pass signal to the cam, but unplugging the cam apparently passed signal to the crank, and without a glitch?? That really led me to believe PCM not using cam signal. But agreed- the PCM is indeed amazingly "smart"- I am impressed for sure!
It was using cam signal ( you scoped it ) until you unplugged the cam sensor then it resorted to the crank signal at the speed of light ( 186,000 mi per second! minus processor speed ) no glitches ! LOL!
Billy R When I scoped it, all I can say is there was signal produced from the hall effect and reached the computer, but, it cannot be said the computer was using the signal provided, wouldn't you agree?
Matt, you are technically correct that you can not definably say the PCM was using the Cam sensor signal, but knowing that the PCM was replaced with a new one, that you are seeing a Cam signal at the PCM connector, why would it not use the Cam sensor signal? Also when you unplugged the Cam sensor after the fix, and after you cleared the codes, did you set a new code? If you did then I would think the PCM is seeing and using that Cam Signal! Wouldn't you agree? Sorry for not getting back to you sooner, had the in-laws over! Fun!
Mine comes and goes. I get a P1353 paired with P0353 and P0351. I replaced my Camshaft position sensor and it fixed it temporarily but like I said, it comes and goes. I think I need a new fuel pump too, going at highway speeds the rpms will stutter and drop a bit. My Jeep has been a nightmare since I’ve owned it😂
Hi Matt as you say there has to be an issue with the fuel circuit it should hold pressure. The usual prime time should also bring it back obviously not in this case, does the PCM not require a Crank Signal to then restart the fuel pump while cranking. Missing or bad crank signal maybe no fuel pump running.
+Niall Seddon Exactly correct- that's why I was still chasing the cam signal but when the hard start existed after fixing the crank sensor and I confirmed cam and crank signals were correct, K had to change paths. The fuel issue is clearly a bad check valve- I will of course confirm next video.
By the way, to find the reason for the starting problem, look for the enable signal going to the fuel pump. It most likely has special signal during the starting and another signal once the engine running is established (via say tachometer or something which confirms that engine is running). Most likely, the signal indicating engine start has some issue. The check valve alone does not explain the excessive start times. As can be seen from the fuel pressure gauge, once it budges slightly, the car is started within a second of needle twitching. That tells me that pressure able to build very quickly and the signal to build the pressure is not coming through for a long time. Can't wait for your next video to see how wrong my guess is going to be!
what do you use as data logger is that your scanner?i just bought my first oscilloscope and next i want to get a scan tool but being diiy hobbiest its hard to justify spending big money but found anything with bi direction costs over $400 is there anything you would recommend for under $500?
What about the P1391? Was the sync system the cure? What years does that work with, the advice from Eric? If cam and crank sensors are okay, then what do you check?
Jeep P1391 CMP or CKP Signal Intermittent Condition. The P1391 was due to the intermittent CMP. The PCM uses the CMP to check the CKP. If they are not in time or one or the other is intermittent the PCM will throw the DTC P1391. PCM uses the CKP to keep the engine in time. I'm pretty sure this is because it is adjustable and the CMP is not. On the I6 the CKP sits on top of the oil pump drive, just the way a distributor would have in older models. Adjustment is a similar procedure except you use a scan tool instead of a timing light. PCM - Power Control Module CKP - Crankshaft Position Sensor CMP - Camshaft Position Sensor DTC- Diagnostic Trouble Code
@@SchrodingersBox Granted the existence of one problem is greater than than having two at the same time. However the symptoms being shown are indicative of numerous causes. Repeated fuel problems in the history is reason alone to check in that direction as well as for spark. As has been mentioned you did not verify actual fuel out of the injectors. I am a newbie at this but in my trade I sometimes get stuck in one avenue of diagnostics while ignoring something only to have my helper point it out to me.
I didnt verify fuel out of the injectors??? How do you explain those fuel trim numbers then and why isn’t fuel pressure higher than spec due to the restriction? How can you say spark is possibly be a problem- what data indicates incomplete combustion and why isn’t fuel trim reflecting a no combustion condition? Why aren’t single misfires indicated? It makes no sense that this could be an injector restriction. What data do you see showing otherwise? You say other variables are indicated based on the data but you don’t list them. For example why didn’t you say a bad O2 sensor a possible variable?Given the fuel trim numbers what are the other variables you suggest could explain those results and why do you think fuel delivery could be one despite the fuel trim data?
My original post about tunnelvision was based solely on several statements made by you in last minutes of the video. Something about getting stuck on something, chasing the starting problem and barking up the wrong tree. Maybe I was just reading too much into your statements. But where I come from that is known as tunnelvision. Since I barely know what you are talking about most of the time I had to rewatch both parts to even try to understand exactly what was going so youll have to excuse my ignore my ignorance.
Not a problem. This video- as all of my videos- are lessons in having “funnel vision” and NOT tunnel vision. By considering all variables and then dismissing any variables that cannot possibly be the issue based on rational analysis of the data, you funnel down to only variables that are possible and then rule them out til only one remains. It is the exact opposite of either tunnel vision where you choose a variable- say spark - and chase that down despite the obvious fact spark cannot possibly be the issue and you change plugs, wires and coils and still don’t fix it. It is also opposed to “cannon vision” where you just shoot down everything equally instead of scientifically funneling to only possible causes. The parts cannon would have put endless parts like a MAF, MAP, plugs, wires, CTS, etc in this jeep. When I first start the video you see I consider everything- MAF sensor, O2 sensors, ignition, fuel, compression, timing, vacuum leak…. but then when I collect data I am immediately able to funnel down that it is either a MAF issue or a fuel pressure issue. All other things are eliminated. It also cannot possibly be an injector issue or a spark issue- the data proves those are impossible. Then by focusing on just only those two possibilities, I was able to rule out that it is not a MAF issue- it has to be fuel pressure. The reading on the O2 sensors under WOT and the pressure test confirmed 100% it’s a fuel pump failing. Not tunnel vision. Funnel vision.
dear matt . could tell me what is happening with my cruise car . i changed the crankshaft it was damaged but i have P0300,P0303 and P0304 no one knew whats the problem !!!! I replaced ( ignition coils,fuelpump,plugs) and( no leaks ) i checked the injectors no problem with them any idea please I hope you will helpe me with this problem.
Yes I can tell you whats wrong. what data did you have that indicated the coils, pump and plugs were bad? Obviously you must have had fuel pressure and ignition voltage data indicating these were the problem- I need to see that data.
+gonz garr There was no logical indication to check fuel pressure. With normal fuel trims under load as indicated by the freeze frame, and only the cam crank sensor code- the logical evidence based conclusion leads to a cam and/or crank problem or correlation failure causing the starting as well as the misfiring, Thats the beauty of this problem- The more you understand performance diagnostics, the more likely you are to bark up the wrong tree on this because of the unindicated problem sharing identical evidence with the indicated problem
+Schrodingers Box I strongly disagree with you on that and willing to argue with you if you desire. Forget the fuel pressure part; you missed the fuel part and that is what is bugging me. I am betting that if you did not have oscilloscope or scanner, you would have then went after fuel and immediately found the reason for no-start condition. Having the fancy tools at your disposal, you forgot the basics. Everybody makes mistakes.
12vgs8606 Nope, without a scope I would have still chased cam and crank first based on the evidence. Sorry bro but with all due respect you aren't "seeing it". Let me clarify: 1. Evidence that the hard start is related to Cam/Crank: a. P0189 recurs even after clearing WITH CRANKING ONLY. b. Long crank time c. evidence was shown in video that no cam or crank signal causes a no start- P0189 is intermittent loss of cam signal d. Timing advance 50 degrees from freeze frame e. FUEL TRIMS NEUTRAL WITH NO STFT ADJUSTMENTS Not to mention I was not even diagnosing a no or hard start- I was leveraging the hard start to get direction on the P0189. Now lets look at evidence the hard start was fuel pressure related: 1. Long crank time. Now- why on earth would a rational thinker based on that evidence possibly say "Hey moron- your problem is you have a cam or crank sensor issue AND you have a bad check valve in the fuel pump"??? What possible indication is there of there being two unrelated issues, with one being a bad check valve (remember- see point E above). And why fuel pressure if you somehow knew there was another problem? Low compression causes random long crank times too but no one called that? The fun part of this study was how an unrelated and actually contraindicated problem shared symptoms with the established problem from the code creating a "logic loop" that a diagnoistician following a logical evidence-based process would fall into.
Fundamentally what did noid light tell you? I think this is where we have very strong difference of opinion. Answer that question honestly, then I will continue from there. Also tell me more about 50 degree timing advance and how that is relevant. Did you notice before and after timing advance?
Not sure if these are one of that needs to have the tank dropped to change the pump, but is there a bunch of crap at the bottom of the tank that the pump is sucking up or clogging the filter which kills it or is it just a common thing with these Chrysler pumps
fuel pump is very bad your test say that or fuel pressure regulator .and you almost done to fix this problem you very very very good tech thanks thanks for great learning video
Smoking Video Matt. Please don't change a thing! You answered my question with regard to the drop out of the fuel injector pulse signal before I had an opportunity to ask it. A flooding condition would make perfect sense! When is the owner of that jeep going to fire the mechanic that over looked that crank sensor and left it like that for the replacement of a PCM and sensor. He should be watching your videos! Two thumbs up. Can't wait to see whats in his tank! Chuck
+Cobra Ninety Six The owner of the jeep did fire him-- actually went back and rubbed this video in his face lol. But the fact is- the overwhelming vast majority of people still won't get it. He would watch this video and see me just wasting a bunch of time.
Well...., good for you! I hope his physician is nothing like his mechanic. He may remove something he'd like to have before a comprehensive diagnosis. 2 thumbs up. ^5
Matt, is this happening during hot starts only or even during cold starts? If it's happening only during hot starts then this indicates that the fuel line cannot maintain pressure, so things like leaky injectors or a fuel line puncture would be likely culprits. If it's happening during cold starts as well then I have to question why the fuel pump isn't priming when the ignition is keyed to "On". Relay malfunction?
+Schrodingers Box It did when you disconnected the CKP. Additionally, from viewing the video when you were jiggling the CKP, when the engine went the roughest it was actually disrupting the ASD relay into shutdown rather than just a misfire as was the case at the other point in the jiggling.
Let me rephrase- now that the CKP issue is solved, what would cause the ASD to cause fuel delivery problems? Seems overwhelmingly obvious to me it's a bad check valve at fuel pump, not shut down problem.
+Schrodingers Box The ASD powers up/controls operation of fuel pump relay, injectors, coil primary, O2 sensor heaters and alternator. When there is a "hard start" problem with a Chrysler product it usually associated with a faulty ASD. So, even though you had injector and coil operation when cranking, a faulty ASD could still interrupt fuel flow because the fuel pump relay is not getting a continuous signal in order to operate the fuel pump. Regarding a KOEO fuel pump prime test (confirmed by a fuel pressure gauge), as you would see with GM and Ford products, if my memory serves me, you will not see this with a Chrysler product because the ASD times out after only two seconds. Finally, sure you could have a bad check valve at the fuel pump, but this doesn't necessarily explain how the fuel line can completely drain from the fuel rail back to the fuel tank so quickly and cause such a hard start.
Hi mate.Well done any way. One down one to go. Normally you would have an over pressurisation valve that returns petrol back to the tank. Could it be that the vale remains open, or partially open? ?dirt in the valve, so the system can't maintain pressure. Marcel.
As soon as I saw spark and injector lights in part one I thought check fuel pressure too. Regardless, you did need to scope to fine the ckp sensor issue. This customer should let you check the fuel pump electrical circuit and put in a real mopar fuel pump. Cheap has become very expensive.
as far as buying a scope, what are the min spec requirements for auto use? I saw a few pocket ones in eBay for around $50 and might pick one up if it would meet the requirements. baby #2 due any second now, so budget is very tight. thanks
Your gonna need to replace the crank sensor ..once the felt is tore off from the flywheel u cant reuse it.. the crank sensor is the issue because its not tight
Without knowing more, I would have a bias in favor of some kind of chemical "pollutant" in the fuel tank, rather than some kind of "sediment" problem. The filter in the tank is awfully fine, so if any "sediment" or physical material is getting into the actual mechanical pumping part of the pump, it would have to be awfully small. Of course it's possible, but my "intuition" tells me to look for some kind of chemical contaminant. That was my thinking as I watched the vid, and as I read through most of the comments. THEN, three quarters of the way down in the comments, Robert Higgins placed the link to the Thompson Fuel Systems video. I just watched the first few minutes, and wha'dya know, he mentions that there was a problem with the plastic in late '90's Chrysler or Jeep fuel tanks leading them to "dissolve", or "deteriorate", or something similar. He also mentioned something about putting E-85 in vehicles that are not engineered for it. SO, if you don't find unusual amounts of sediment blocking the tank filter, I would say flush the tank very clean, put in a true Mopar brand pump (as others have suggested), and see what happens.
+John Burke On most cars, yes- there is a 4 second prime that starts with the key in the on position. Not all cars have this though. But the main thing is how this car loses fuel pressure totally and immediately when engine is turned off- there is something wrong with the check valve for sure
+Shawn Lockard My opinion is there is probably sediment in the fuel tank that is never cleaned out. Since the starting problem is surely the check valve, I will surely have to drop the tank and I can verify the cause of the frequent failed pumps
+Schrodingers Box , you are probably correct, on flat rate you do not bother to check for that. That system only filters the fuel it uses so sediment could pass through the pump many times before it ends up in the filter. Resistance in pump wiring would be far more interesting to diagnose.
yes I don't remember if I choked voltage drop last time but for sure I will do that as well. I agree- no incentivefor a professional on flat rate or especially hourly to clean out a tank
+Schrodingers Box looking forward to your next video. Can your customer get their money back on the PCM? A new cam sensor would be semi reasonable if is a common failure and cheap but a new PCM is incompetence.
I always say the only thing worse than having a problem is having multiple problems. I was yelling at you in part 1 to put a fuel pressure gauge on it since the jeep had previous pump problems. Guess you didn't hear me...LoL. The cool part about not being sure how the system works is that you reasoned it out logically and finding the crank sensor "butchery" was a huge step toward the diagnosis. If I had to do work that way to make a living I would shoot myself in the head. {:-) I find that sometimes on a Chrysler a failing crank sensor will set a cam sensor code or vice versa because it senses a correlation problem between the crank and cam sensor but the PCM can't zoom in on the correct sensor. (Chrysler engineering)...BLAHHH.Can't wait for the fuel pressure issue diagnosis. Keep learning.
+wysetech2000 In a logical approach you have to go with the evidence. Fuel trim data indicated no fuel pressure problem and he recurrence of the code during cranking plus he misfire issue all indicated command for fuel and spark must be indicative of timing rather than fuel pressure. A lot of people don't understand this because they don't see the beauty of the logic circle created by two independent problems where the indicated symptom just so happens to superimpose the unindicated symptom. That is the point of the whole video but I don't think people see it.
The CKP sensor was obviously worked on. It is missing "A wire shield/router is attached to the sensor" # 3 - WIRE SHIELD, and CKP sensor had been worked on or possibly removed, was a new #6 - PAPER SPACER installed or is the old one still there? This may need to be looked at. Found image of the shield at 5:00 of this video (I do not endorse the video but did find this image of the actual shield here to illustrate). ua-cam.com/video/7D0vUEDSwXo/v-deo.html Couldn't find one of the spacer but #6 in this parts diagram is it. This should be replaced I think if the sensor is removed. Image google - www.google.com/search?q=2004+jeep+grand+cherokee+crank+sensor&rlz=1C1_____enUS522US523&es_sm=122&tbm=isch&imgil=ckVSM0DzRM0lSM%253A%253BCkEdqCamUWJhLM%253Bhttp%25253A%25252F%25252Fwww.jeepz.com%25252Fforum%25252Fcherokee-commander-wagoneer-liberty%25252F27678-2004-grand-cherokee-4-0-cranks-but-will-not-start.html&source=iu&pf=m&fir=ckVSM0DzRM0lSM%253A%252CCkEdqCamUWJhLM%252C_&biw=1184&bih=580&usg=__joxSCXTWguyvAsS1pVEqOHAut2I%3D&ved=0CGQQyjdqFQoTCLeNjMj-6scCFdKOkgodhVYLMw&ei=A7HwVff_G9KdygSFra2YAw#imgrc=ckVSM0DzRM0lSM%3A&usg=__joxSCXTWguyvAsS1pVEqOHAut2I%3D
Perhaps it was the very observation of fuel pressure that ultimately caused the low fuel pressure to become reality. In which case who could have ever suspected a condition that simultaneously was and was not? Schrodingers Fuel Rail.
Hi Matt What happened to my favorite FASTTEC method? Dump the Noid light it is for the birds! Did You notice in part 1 that the freezeframe data showed 50+degrees advance at 896RPM? Greetings, Bernhard.
+Bernhard List FASTEC was not used because of overwhelming evidence that cam or crank signal was responsible and so I went with the evidence available until I finally excluded it.
+Schrodingers Box Actually I do like Fasttec so much that I added one item and made it FASTTREC, the R standing for Reference Circuit and Electric Component because it can also stop a car from starting. With me having still very little practical experience I could fix 3 cars already useing your systematic approach, so I will just stick to that. Thanks Matt
Bernhard List Yeah the R may stand for "redundant" though lol- because a reference circuit will still cause either Fuel and/or Spark failure. The idea with "FASTEC" is these are "raw sources" of which the explanation for that missing source must be found.
+anita brodie Why? There is proper regulation of fuel pressure under load vs under idle. The fuel pressure regulator also does not control the static pressure.
final diagnosis was fuel pressure but you said the 1391 still the only code. did u find out if they work together somehow to get the code I changed cam and crank but still get rough idle every other start up.
I got the same p1391. I read in some thread of jeeps having issues with the cam/ crank. drove the cat with no issues for a day then light came back on. all I have is a volt meter to check the ref voltage and it was fine. on the 4.7 u have to remove the stater to get to the crank so it was tough for me to try to check for v drop.
Luis Contreras Lots of things can cause a P1391- and just because a thread says what the issue was- first, it doesn't mean that's the same cause of your issue and second, they were lying anyway because they don't know what they're talking about either. As it stands you need to verify signal, ground and reference- anything else you do is a guess at best and waste of time and money at worst. I usually save time by just doing a cam and crank sensor bypass to verify circuit integrity and if the bypass fails then I narrow to the side of circuit with the fault.
Luis Contreras have you checked ignition timing 1391 usually caused by crank sensor shaft/oil pump drive off time a few degrees. Loosen hold down rotate a lil till sync signal in spec I can get u specs if needed
dude i absolutely love how you walk us thru your whole thought process on this one.
I realize this video is a few years old, but I'm glad I found it. I wasn't having a problem, I'm just kind of consumed with watching diagnostic videos to learn even though I've retired from a different field. This is what I do instead of watching tv. Anyway what I wanted to say is that watching you step through this made me see that you never strayed from your strategy of teaching investigation over parts changing. So many times when you or Eric O. or Scanner Danner and others head down what looks like a wrong path you find a problem by being on that path. That is the big lesson. Besides learning, it's really enjoyable watching you succeed. Thanks again.
thanks for the comment. glad to be considered in such good company too!
Thank you for letting us learn with you. I really appreciate that you keep in all of the highs/lows successes and let-downs. Its good to see that. Many videos edit out those more frustrating portions, which cuts out a lot of learning opportunities for the audience.
Excellent video. As a shop owner I'd hire this guy in a heartbeat, understanding how something works and how to use your resources is the key to correctly diagnosing and repairing. Nice job
Anytime you EVER EVER EVER have a long crank time one of the first steps should be checking fuel pressure. This video is gold Matt, diagnostically golden. Kind of sad that a dealership technician couldn't fix these issues but on the other hand it validates your skills as a DIY technician and the purchase of the oscope. Congratulations on a superb and vindicating video. Bravo. To those that think he missed the issue of the no-start like he completely whiffed on the diagnosis, he in fact did not. He 100% fixed 1 of 2 issues and confirmed 2 major separate issues. The crank sensor would have eventually completely failed and left the owner stranded, just a matter of time. I hope we get to see a Part 3 where you trace back the culprit of the bleed down and fix it!
+DJDevon3 When most cars have a loss of cam or crank signal you will also have a long, long crank time. Try unplugging the crank on a VW- it will have a long cvrank time.
Schrodingers Box Most DIY'ers don't have scopes so the first thing i would break out is a fuel pressure tester. I'm in no way implying that you did anything wrong diagnostically. In fact you did a superb job, certainly better than I could have done. It's why I'm a subscriber. ;)
This is one of those times where there was more than one problem, even if it wasn't apparent at the time. When there are multiple faults, you have to fix the most "obvious" first before any other faults become obvious, and can be tracked down.
mrman17 It's easy in hindsight to nitpick and play armchair jockey. You're right. My apologies.
***** No! Don't get me wrong, I wasn't criticising! I was just commenting...
You did great Matt, I have encountered driveability issues on Buses where I have found multiple problems cause the main problem. Because of this one of the first things I do on a driveability issue is I do a battery,starting,charging system test because if these components are not working right, nothing else will.
Those crank sensors are adjustable. You'll notice that the bolt sits in a slot. Shop manual says to use a tab that is available and stick it on the end of the sensor. The tab is a small piece of cardboard about the thickness of a business card with sticky on it. With the tab on the end of the sensor push the sensor in till it sits on the relucter ring part of the flywheel then tighten the bolt. Using a peice of business card with a spot of grease works good. The tab or business card is thrown out when the engine is started. If the sensor is too deep it will scrape the flywheel, and if the sensor is too high it wont run. If the sensor is slightly too high it could work then quit later. (seen it several times, cuz I was in transmission industry for 26 year and we pulled hundreds of those transmissions with crank sensors passing through them.
+CoolAirVw Yes that part I knew... however along those lines, since the video I have done some research and also noticed that the cam sensor was clearly installed incorrectly by the previous shop and in fact I did not set the sync correctly with my scan tool either. Currently the vehicle is almost 20 degrees off with the cam signal. When I get the vehicle back this will be adjusted correctly.
Another awesome diagnosis video! If after all this, you don't end up hating Jeeps and can gradually become an "expert" on them, you will be a global hero to all us Jeep owners. Online forums are jam packed with Jeeps suffering from random stalling/no start issues (experiencing this myself right now), with members offering countless solutions that are all over the board. So with this Grand Cherokee you're working on, I myself am anxious to see you resolve it for the owner. Thanks again Matt - you rock!
+Steve C This is really not the jeep's fault. The code was absolutely correct (though would have been nice if it differentiated cam and crank instead of combining them. The starting problem is obviously a bad check valve. But since there is no pressure sensor on the rail, the jeep cannot possibly "know" this and with normal fuel pressure when engine is running and normal fuel trims, the fact is- the jeep PCM made the right call with the cam/crank code being the only code.
Well done Matt we all learnt that it's not so easy fixing cars and in the end you found the problem. 👍
Matt thanks for showing this video .I learned loads from this and will keep in mind that sometimes you can just focus on a certain point from the scan tool code and that more than one fault could be a possibility .Great that you found the issues.At the end of the day your logic came through and you did not throw hundreds of dollars at it.
….. so I’ve been dealing with a P1391 code on my 04 Rubicon for about 3 months an I’m about 90% sure you just showed me the issue, I’ve replaced my OPDA, IAC, MAF, TPS, all 4 02 sensors and all 6 spark plugs trying to fix my issue. Really thought I had in about a week ago by unhooking the battery draining the system an making my computer basically do a reboot. I don’t have a starting issue but a very intermittent miss fire with no miss fire codes. I subscribed and liked your video. If the CPS ends up being my issue as well I’ll let you know but thanks for a very informative video.
I think your mistake was believing that you had fuel when the "NOID" type light was flashing. That flashing only tells you that you had control signal to the fuel injector. By no means did it provide an indication that there was pressure in the fuel rail to go through the injector to the cylinder. You got it though. Good job!!
CORRECT AND GOOD POINT
I don't see that as a mistake. He needed to see if the computer was telling the injector to fire. There was a problem with the crank position sensor. Just needed follow-through with measuring rail pressure, especially since it had a history of failure. You can't go down two paths at once.
You will always run across something you do not know so you just fall back on the scientific method. Systematically rule out what it is not, until you find out what it is. Great demonstration of that procedure.
Well said!
Actually IMO seeing someone bark up the wrong three is by far more useful than watching another "hey, watch me fix this loose wire or replace that fuel pressure valve" video. This debugging is where I spend 80% of my hobby shop time.
Thanks for taking the time to record and edit and hope for more problems in the future ;-)
+Dawid Ciecierski Absolutely true! In fact, better to use an illogical approach but still test everything along the way than to just parts change in fact.
But this is precisely how I learned everything I know- it's the trial and error that does it. And the research I am forced to do too.
Kick ass diagnosis, Matt. Whoever did that crank sensor should be fired. Out of a cannon. Into the sun.
+Adrian Kingsley-Hughes Agreed!!!!
OMG, I finally got one right! I'm no cam/crank expert but in PT.1 I was thinking of fuel pressure when the light went off, I was thinking that the fuel relay may have a timer or something in it that kills fuel if the engine hasn't started in X seconds. I thought for sure you were gonna check fuel pressure right then, because you alluded to fuel pump issues in the past. Great Vid, that's why I watch, I been learnt something today.
+Jason Beattie Yes but there was no logical reason to expect fuel pressure based on the fuel trim indications from the freeze frame data, wouldn't you agree?
+Schrodingers Box You need FAST (or something like that!), right? You did not follow your own procedure to diagnosis a no start condition. I can't believe you are still making excuses.
100 incorrect. I did follow fasttec procedure- the evidence based on timing advance, fuel trims and the code indicated to triage the ignition timing.
Why would you think Fuel pressure FIRST when you have recurrent 0189 when cranking and lift at zero with no STFT adjustment and 50 degrees advance???? please explain your rationale.
Matt, I'm currently a reformed 98%er so, fuel trim and freeze frame do not yet enter my thought process in regards to fuel pumps.. This is why i watch your videos because misdiagnosis is the bane of my existence. I, like you, cover parts that I misdiagnosed. These are cars that we work on not space shuttles, with the right understanding and correct information, part changing shouldn't ever happen. Keep up the great work!
Jason Beattie Well if variables and data are not included because they are not understood, that certainly will narrow down the troubleshooting chart.... but due to what is known as "false dichotemy logic fallacy"
When reinstalling the crank position sensor, there is a paper decal that can be purchased from jeep to properly set its depth. The paper decal will rest on the flex plate and will be torn off when the engine starts. If ithe crank sensor is installed too deeply it will be destroyed by the flexplate. This also needs to be reset any time the transmission is separated from the engine, because the sensor is on the transmission bell housing and the flexplate is attached to the crank.
Reprogramming of the crank position sensor should only be needed if the 'oil pump drive gear' that the cam position sensor sits on had been tampered with. This is noticeable at high engine RPM under load when precise timing become more important. It also controls injection timing so there would be issues there at higher RPM's as well. Not mentioned in this video setting the the cam position sensor with the toothpick just gets it in the ballpark, needs to be finished with a commercial grade OBDII scan tool.
Ok so I’ve swapped the OPDA in my 2004 Rubicon. I’ve had it hooked up to a couple Newer Snapon scanners an according to the scanners it runs great around -30 with the timing. If I get it locked down around 0 it idles great but face plants with any amount of gas… really thinking I need to take a look at my Crank Position Sensor as I have had my trans out and back in multiple times in the last year or so. Replaced the sensor once but not in the last couple times that I’ve dropped the trans.
@@PureToxicYouth At -28° I would intermittently loose spark at higher RPM's and sometimes have to re-start the engine when one of the coil packs would just stop firing. Now at 0° no issues.
Are you sure you are at TDC with the toothpick installed in the CKP?
@@markcarpenter3600 unfortunately my OPDA didn’t come with the holes to do the toolpick trick but it came with a plastic retainer to hold it in position when installing it. I’m about 90% sure I was TDC on the #1 cylinder when I installed it.
I would say that getting vehicle history is important and that even a professional tech can really screw the pooch....in addition I would say that unless some symptom is very obvious checking the main three contributions to combustion should be put on the table in most applications. good set of videos Matt, well done.
Hey guy, I enjoy your videos and approach to troubleshooting, everyone can learn a bit from you and re-think their approach to troubleshooting, be it good or bad, and i appreciate your efforts. I link your videos to a lot of folks to learn and disagree as well.
Just a heads up, i had a vehicle with damn near all of these symptoms same codes and odd drive-ability concerns - an intermittent transmission starting in second gear, In my case, it was a bad harness connector on the firewall.
I am not sure how common that is, but it ran me in circles until i figured that out.
In my case,The wires deliberately pulled tight like in your video were a clue.
Also something to consider on some Chrysler engines, if you yank the cam sensor and it cranks, you have a usually have a timing issue, the two signals are fighting each other in the pcm if they are not in sync, it wont crank. You unplug one, and vroom + code.
I assume it is a safety thing to save your engine if it is of interference design. if the engine has a timing belt, its probably off a tooth off or so. if it has a timing chain, most likely a failing tensioner/guide/sloppy chain.
LOL, I have a 97 Wrangler that has always needed a 5 second crank/stop/ crank in order to start. I just figured it was a quirk I had to live with. The first crank could be 30 seconds and it wouldn't start but a brief initial crank and it would start and run fine. I didn't watch this video for that information though. Just purchased an 01 GC and needed some info based on the topic of the vid...learned two things in this one vid.
In this case I would try to prime the fuel pump multiple times WITHOUT cranking to build fuel pressure, then should be more likely to start when you crank it
Its all about the struggle....Its just more fun when your the one struggling :)Im guessing the Starter will be the next Item to go...............Nice video Matt.
+Charles Miller I talked about how much more fun it is for another to struggle video 1 too, lol. Sorry Matt, but when there's struggle we think the hardest.
I'm thinking starter next too! lol
Well done,not all repairs are easy and some are more complicated than normal.
The crank sensor has a felt pad on it . Its a one shot deal... once the felt gets ripped off after thr car starts YOU CAN NOT LOOSEN THE BOLT or it will rub on the flywheel and toast the sensor .. for being the bolt was loose i guaranty the felt got torn off and the sensor is rubbing on the flywheel causing the issue to the fuel pump , jeeps are tough to diagnose... i have 5 of them .been there done that. I have seen it all with these things...good vid 👍
Great video! I won't arm chair quarterback but I will say it is nice to see your human like the rest of us.
To get to the crankshaft sensor the beat way is the driverside floor opens near it nd u cn get through with an extension no problem to tighten
that made me laugh after i read the disagreement between you and the other guy on your last video that said you should check fuel pressure as soon as you saw you had spark and injector pulse. lol
+lolz larkin Lol he was right but for the wrong reason, I was trying to get him to see that. But yes I already knew the whole time he guessed right. But he obviously didnt watch the video so he thought this was just a cranking no start diagnosis. In that case he woulod have been 100% correct
Well I think you were secretly hoping it was a ckp/cmp sensor problem because it would be perfect for the channel.
You'd be surprised at the amount of people I've seen chasing their tails looking for something complex and it turns out there's no fuel in the tank, or there's an e-stop pressed somewhere they forgot to check.
lolz larkin Well there was a crank sensor problem of course but yeah, not the one I was hoping for- I was hoping for an intermittently grounded signal or 5V wire or something lol... but glad that thing is out of here- I got sick of looking at it and it took my whole saturday!!
Well if you'd have done what that other guy had said... ;) lol
lolz larkin "false conclusion fallacy" is still logic fallacy even if the conclusion is true.
Great detective work Matt. Enjoyed the 2 part video.
+White Tiger This was a great one!! Having two completely unlinked problems that share the same symptom indicated by a single check engine code created a "logic loop" that sent me up the wrong branch as a direct result of my logical process!! Someone who didnt know anything about cam, crank, fuel trims, or timing would have solved the cranking problem much faster for sure. life isnt fair lol!!
My cam sensor was broke for a while didn’t know it, fixed it! Thanks
Great dx... Makes sense. Taking a few cranks to build press. In the rail.... Way to think outside the box!
Set sync signal is a great tool. I had your same p1391. Dtc on a 98 Cherokee my self and the guy b4 me threw a cam sensor and shaft at it. I had to use sync signal to see he installed shaft off time by some amount of degrees. I retired engine and dtc went away. You would then use set sync signal and turn cam shaft sensor shaft till with in specs/proper degree (ignition timing)
Great job Matt. Good not to stay so focused on one thing and overlook other options along the way. On my VW, the car works fine on crank sensor only but has a long start. The car will not work on cam only and stalls when loses crank sensor. The cam sensor is used by the computer to find TDC of cylinder 1 for much quicker starting.
+John Fountaine Yes same with my car as well, another reason I thought the cam sensor bad because long crank time is a symptom
I remember there was a youtuber (the channel name has a picture of pussycat and some unknown scientist) who presented a great video about how to methodically diagnosis a no-start condition; he even had an acronym (FAST or something like that) for it; may be you should watch it? :-) You do deserve all the bricks that you are (or should be) getting for this one! I mean when I saw spark and injector firing, I am yelling from my keyboard "check the fuel, Matt!"
+12vgs8606 I did follow fasttec- the evidence overwhelmingly indicated timing as the top of the triage and in fact, based on the fuel trims and timing advance, fuel pressure was actually CONTRAINDICATED.
Shall we look at the evidence here? The car came in with hard start, perceptible misfire during running, code indicating cam or crank signal failure.
1) visual inspection showed loose crank sensor
2) noid light and spark plug tester proved injector pulses and spark control from ECM
3) the hard start particulars:- when the car eventually starts, it runs great i.e. there is no rough running for a second or two after the car starts. Just this clue alone will tell you that it was not getting the fuel when it was not starting because if it was missing the spark, and if the spark eventually started firing, the engine will start but it will be coughing until it burns the excess gasoline.
4) the engine has timing chain; so highly unlikely it was slipped; besides both actual spark and fuel control were observed; if the timing was way off, you would have whole bunch of backfire.
5) "I have no time" was mentioned too many times in the video
6) There is absolutely no way that you have provided any justification for not checking the actual fuel once you had spark and injectors were firing. With 99.99% certainty, you should have known fuel was not getting to the cylinder. Heck, I probably have less than 10% of your knowledge and skills but many clues were present in this situation to know that most likely cause was no fuel. It is irrelevant what the freeze frame data or the fuel trims were on that engine.
I am disappointed that your ego is not allowing you to accept the fact t
12vgs8606 Like everyone else you just simply dismiss Timing as a probability despite the evidence
Timing as a probability was dismissed because the engine behavior when it did start did not indicate timing issue.
One has to take in to account *all* of the evidence. Apparently, you are the one who is ignoring some of it.
12vgs8606 OMG dude- killing me. Not if the signal is handed off to the "working" sensor.
enjoyed the video, good auto repair geek stuff once again!
hi mat the reason i said the fuel filter regulator is because the fuel system you are working on is not a returnless fuel system the fuel filter regulator has three lines inlet outlet and return that means the fuel regulator must also have a check valve (source all data fuel is supplied to the filter regulator by the electronic fuel pump the regulator acts as a check valve to maintain some fuel pressure when the engine is not operating this will help start the engine a second check valve is located at the end of the electric fuel pump )
+anita brodie Hmmmmm I was pretty sure the regulator is in the filter but check valve is surely on the pump outlet. I will have to check on it- Ha, check on it- get it?
Great video and entertaining.Making assumptions can be hazardous.A thorough background understanding on the complete engine operation is a priority but can be very time consuming with so many variations out there.
+Tom OConnor Yeah I ran into a real conundrum here... like you said there are sooooooooo many variations and the research would have been literally hours. I only had 6 hours with this truck and filming triples my time so I was in a huge rush. It was simply impossible for me to do the research I needed to do and yes, I had to make assumptions of the functions of the sensors some of which obviously turned out to be wrong. This is a definite case where more research than wrenching is needed.... how many people in the whole world are willing to do that? So far I only know of about 30,000 lol.
as always, loved the video. Thanks!
Great video ,thank you for what I have learned from you .I love whatching your videos over and over again
.I am better in my job ,I work in an auto shop ,thank you.
+Carlos Dorantes Awesome of you to say that man. Most people that work at shops wouldnt admit they can learn from a DIY. But I learn from you guys too- my favorite subs are professional mechanics. They really make the channel what it is.
Awesome video Matt, since no two mfgs do things the same way. Dealer tech gets to go to school every time something new comes out. We are not so fortunate so working on different brands can be challenging. you did an excellent job of narrowing it down . Excellent work. Thanks
totally true bro! Totally.
Thinking some more, the pump seems to run perfectly once it is operating. Could this be something like a relay or regulator/check valve problem? Because once the car was running and the ckp was correctly fitted, it didn't miss a beat. So it's not holding pressure without the pump running. Close?
By the way, I really like your shirt!
+Mathew Wood exactly correct again bro. Damn kid- you got it down!! Yes a bad fuel pump check valve is almost certainly the issue. A relay problem explains the hard starting too, but not the immediate drop in pressure to dead zero when engine stops. A check valve explains both though. Of course- after this video it could be a bad relay AND a bad check valve lol!!!
Thanks Matt. I'm starting to think more about my conclusions before I actually go ahead and start repairs, thanks to your explanations and tutorials. I really appreciate your work, thanks.
Very nicely done! Thank you for an awesome video, learned a great deal.
Almost instantaneous pressure rise during extended cranking preceding startup suggests power is being interupted to the fuel pump. Perhaps main fuel relay or wiring issue. Check valve may not be a factor. Great video. Easy to get fixated on one aspect of a problem and forget basics. regards
Another great video. I like how you dont loose your cool and keep looking logically!
+ksauto1 Lol- it is sometimes very tempting to just say "aw hell throw a MAF at it" but if I am wrong, I have to pay for it out of my own pocket. Plus also can you imagine the backlashing I'd get if I just gave up halfway through and guessed at a part!!!
MATT, HELLO I am a little late writing this but what a great info and process of thinking to approach this kind of a problem even some professional techs could not know how to do just want to say big thanks to all the knowledge that you share and waiting to watch the part # 3 i hope cheeeers my friend .
+j georges Cheers to you as well. Customer is saving money for the final repair and we will finally learn what keeps eating fuel pumps on this thing!!
I'm having the same problem on 1999 jeep with p1391 having problems cranking and running, the fuel problem could also be my problem? I replaced the cam censor a while back seem to fix the problem but recently started back, could changing the cam censor compensated for the fuel problem if have one, I'm going to check the fuel problem tomorrow
depends. what was the data you got that indicated the cam sensor was at fault? Was a bypass done? what were your reference and power inputs and how was ground verified?
Nice job man. Superb skills. I learned just watching. Thanks for the video👍👍👍
If you think about it the only time the control unit needs to know the cam position is at start up and then only +/- 180 degrees. Spark timing is probably determined by the flywheel sensor with many more teeth (higher resolution). You also need to find out the sample rate of your scope and compare that to the frequency of the signal you are looking at.
+Richard J Lebens Hmmmm good point, I never considered that- makes perfect sense. Totally explains no start when can sensor disconnected but no effect when engine running and its disconnected.
+Richard J Lebens
Even the slowest scope in the world is going to be more than fast enough to watch cam sensor signals and crank sensor signals. Your point about the crank sensor signal having higher resolution is interesting.
+douglas lee I was pointing out the relative fundamental frequencies of the signals. The cam sensor was 6 Hz (15 running) and the Crank sensor would be (150 (?) flywheel teeth/rev x 900 rev/min * 1/60 min/sec =) 2250 Hz. (Did I do that right?) Usually on a digital scope when you turn the time base down the sample rate matches the display resolution. I did not look up the specs on that scope. The ECU also has to know precisely crankshaft TDC. I wonder if that was some of the crank signal weirdness.
+Richard J Lebens
Richard, I'm not sure if I'm totally following you, but I think I sorta do. The main point you're making is that the signal in question would be around 2250 hz, right? Well, that's nothing for any scope, whether digital or analog.
By adjusting the time base knobs or buttons, the operator will be able to put the scope in the correct "speed range", and then the auto trigger (or a manually set trigger point) will take care of the rest.
+douglas lee That is true. I was concerned with aliasing and not bandwidth. I was trying to point out you couldn't look at a real slow signal and a real fast one on the same screen without verifying the sample rate was sufficient to capture a reasonable representation of the faster signal. I should have put that in the first post.
At the start of part one you mentioned that fuel pump problem and I thought then that perhaps it could be the issue but , like you, I didn't give it another thought until you went back to it. Good find, Matt and thanks for another great video.
Yes the evidence seemed pretty overwhelming for only the cam crank problem causing everything. What hooked me was if you cleared the check engine codes the code came right back on just from cranking- obviously this was because vibration from the cranking was wiggling the sensor but it sure seemed like it was because the cam or crank was causing the hard start.
Good job on both the video and the car --- I wasn't expecting the fuel pump Issue to be the cause of the non-starting.
The case well illustrates the value of a scope for checking crank, cam sensors and also applies to wheel sensors.
I have had run-ins with cam and crank sensor my self and now wouldn't be without scope, I mainly work on the same type of engines ans so have made breakout connectors from scrapyard and cast off parts to allow quick connection.
The cheaper USB or palm sized scopes are now well within the DIY mechanics price range under 100/£70/100 Euro.
Good of you to mention that there MAY have been a better diagnosis path you COULD have taken....like you said hindsight is a wonderful thing.
Take the crank sensor issue though...it needed sorting, so in fact there was no wasted time at all.
And often in diagnosis, knowing what is right...verified right...leads to finding out what MUST be wrong, which can then be verified.
Good 2 part video, enjoyed it...thanks.
+Ian Muggeridge Yea you totally get it. A better diagnosis path would have involved understanding of the responsibility of the cam and crank sensors for this specific model. It would have allowed me to much quicker dismiss that the cam signal was indeed being used by the PCM and I would have abandoned my initial strategy of leveraging the hard start as a diagnostic strategy
Matt! Wow that was a good one! Totally agree about the blindfolds...we have a code, so that is the problem right? With most cam-crank codes, my weapon of choice is a scope (you already have that covered :) and a reliable wiring diagram. Check out the free BBB Industries database...only takes a few seconds to pull up the correct manufacturer diagram with wiring colors and connector pins.
So why the heck does that Jeep eat fuel pumps for breakfast?? Wouldn't be surprised if the starter takes a crap soon too...looking forward to the next Jeep vid!
+motoYam82 Yeah this was a good example of how a logical approach can actually take longer than guessing lol.
I should have jeep next week and I will diagnose it for sure
+Schrodingers Box True, but the "logical approach" only takes longer on the initial learning curve...like you said doing the research on these systems that vary by manufacturer takes a lot of time. Looking up a diagram and hooking up the scope is usually the fast and fun part :)
Guessing/swaptronics on the other hand might initially take less time, but there is no learning curve at all haha. I'm surprised that the Jeep owner agreed to pay for all those unnecessary parts before bringing it to you!
motoYam82 Well its hard to earn credibility when you're not a mechanic and you do this stuff out of your home garage in a residential neighborhood. But I definitely earned his respect after this one lol
Yup, got tunnel vision on a Saturn L300 thinking it was a fuel delivery problem after running 10 minutes and die. Started thinking after the vehicle would start then die after 10 minutes of running, I was looking at something else. Sure enough cam sensor would show open when I ohm'd it. Great vid!!
+Beau Michna How did you ohm test a cam sensor? I can see how you would go between feed and ground? How would you diagnose the signal loss??
+Schrodingers Box Didn't have CEL. Went on Saturn forum (don't judge, was pressed for time😏) after heating up, sensor showed open, replaced it, no issues since.
+Beau Michna Forgot to mention it was a two wire not three.
+John Kobberstad Matt didn't make a mistake with reading the noid light, as the fuel trims showed no issue. Why would he be look for something that is not indicating a fault? The fault indicated a cam sensor issue, so the noid was used to check for a cam signal, yes?
+Mathew Wood DING DING DING WE HAVE A WINNER!!! Exactly correct bro. The thing is most of the people who think I made a mistake not checking fuel pressure are ones who don't understand interpreting fuel trim and timing data. If you dismiss the codes, fuel trims, and advanced timing from the freeze frame data because you don't understand it, then yes, you would check fuel pressure as a next step.
Schrodingers Box yeah, it's an illogical conclusion to say you misread the noid light. Also, how many of these genius parts changers would have changed the pump, the filter, maybe even injectors before getting to the actual cause?
Mathew Wood in all honesty, for my viewers, very few of them i bet, actually. Its more a matter of understanding the logical process here, but they would still not have guessed on parts I am sure
Schrodingers Box I was more referring to the other 98% as you put it. I should have been a little clearer.
Mathew Wood Oh in that case for sure bro... for sure. I would be shocked to see otherwise.... actually I never have. Every car I ever see that was seen before me had at least one thing changed... usually more like 7
Thanks for a good video. Nice to learn along side you.
+Jim Hanley Nice to have you here!
Hey man really enjoy your videos by far and learn quite a bit from you.I dont throw parts at problems either.Keep up the good work
Right on!!
this video helped me with the same code i had with a jeep nd it ended up.being that the camshaft was loose tightend the bold.eared the codes nd nothing came back thanks for the help
Haha. That's awesome. At part 1 I thought: i don't know, but the no start will not be related to crank/cam for sure. In some video from past you said that with nostart condition you always do a few basic things like spark, fuel, timing etc. I set this as my golden rule and it works 100%.
Ofc I understand why you run into all this problem here... But just keep using your own rules bro :)
Excelent videos, excelent case, great as always actually. You are still my favourite diagnosis guru Matt.
The only thing that bothers me is you mentioning the time. A few times. Its a little bit anoying to watch you being in hurry. Especially with such an interesting case.
I'm pretty sure you can just edit the video without mentioning you are in hurry and it would be way more fun to watch.
Other than that - looking forward to the next one!
+messer7bc Just curious what was your indication the starting was not cam/crank related when there is only a cam crank code and regular misfires?
+Schrodingers Box It was not completely clear from the beginning that there are intermittent misfires so I was not really worried about that. I only knew the car history from previous videos (yeah, you had pretty hard time already before with diagnosing fuel pump), the symptom (intermittent nostart condition) and check codes. I don't work too much with scanner tools (mostly because I work with older vehicles) so my focus would definitely go in direction of fuel delivery first (and actually you did this test with the bulb attached to injector, but you've only checked if injector is managed by computer, not if the fuel goes into cylinder...), then ignition (and you've checked that), then timing... Actually after you did a test with spark tester and fuel injector bulb - it was pretty clear it's not crank/cam and it needs to be related to fuel and/or timing. Probably after that I'd experience misfires so this would be next in my list and this diagnosis was really great in your video!
Maybe it's just because I'm less scanner-scope-electronic oriented guy and more mechanical oriented one.
And that's why I'm here to learn this scanner-scope-electronic stuff from you ;)
Matt, great fix! Again, and I know you were pressed for time, but if you scoped your cam and crank signals after the fix you would of definitely looked in the direction ( fuel ) that you did because of the cars history and symptoms. You also just proved how smart them PCMs are when you unplugged the cam sensor as it was able to calculate the cam/valve position for injector timing based on crankshaft position.
+Billy R Yeah but what really threw me is why unplugging the crank didn't pass signal to the cam, but unplugging the cam apparently passed signal to the crank, and without a glitch?? That really led me to believe PCM not using cam signal.
But agreed- the PCM is indeed amazingly "smart"- I am impressed for sure!
It was using cam signal ( you scoped it ) until you unplugged the cam sensor then it resorted to the crank signal at the speed of light ( 186,000 mi per second! minus processor speed ) no glitches ! LOL!
Billy R When I scoped it, all I can say is there was signal produced from the hall effect and reached the computer, but, it cannot be said the computer was using the signal provided, wouldn't you agree?
Matt, you are technically correct that you can not definably say the PCM was using the Cam sensor signal, but knowing that the PCM was replaced with a new one, that you are seeing a Cam signal at the PCM connector, why would it not use the Cam sensor signal? Also when you unplugged the Cam sensor after the fix, and after you cleared the codes, did you set a new code? If you did then I would think the PCM is seeing and using that Cam Signal! Wouldn't you agree? Sorry for not getting back to you sooner, had the in-laws over! Fun!
Mine comes and goes. I get a P1353 paired with P0353 and P0351. I replaced my Camshaft position sensor and it fixed it temporarily but like I said, it comes and goes. I think I need a new fuel pump too, going at highway speeds the rpms will stutter and drop a bit. My Jeep has been a nightmare since I’ve owned it😂
what data showed the camshaft position sensor was the problem?
So to be clear the only thing you did to the crank sensor was tighten the bolt? How loose was it?
thanks matt for another knowlegleable work i really come to know how fuel pressure can effect starting issue thumbs upppppp
Hi Matt as you say there has to be an issue with the fuel circuit it should hold pressure. The usual prime time should also bring it back obviously not in this case, does the PCM not require a Crank Signal to then restart the fuel pump while cranking. Missing or bad crank signal maybe no fuel pump running.
+Niall Seddon Exactly correct- that's why I was still chasing the cam signal but when the hard start existed after fixing the crank sensor and I confirmed cam and crank signals were correct, K had to change paths.
The fuel issue is clearly a bad check valve- I will of course confirm next video.
By the way, to find the reason for the starting problem, look for the enable signal going to the fuel pump. It most likely has special signal during the starting and another signal once the engine running is established (via say tachometer or something which confirms that engine is running). Most likely, the signal indicating engine start has some issue. The check valve alone does not explain the excessive start times. As can be seen from the fuel pressure gauge, once it budges slightly, the car is started within a second of needle twitching. That tells me that pressure able to build very quickly and the signal to build the pressure is not coming through for a long time.
Can't wait for your next video to see how wrong my guess is going to be!
+12vgs8606 If check valve not the issue why does pressure immediately drop when engine turned off?
what do you use as data logger is that your scanner?i just bought my first oscilloscope and next i want to get a scan tool but being diiy hobbiest its hard to justify spending big money but found anything with bi direction costs over $400 is there anything you would recommend for under $500?
so was it ckp and fuel pump THE problema?
nice video I have been learning a lot strategies about fixing cars with your methods of thinking before replacing parts,.. keep the hard work!!!
+Alan Reyes Thanks man! Will do!
What about the P1391? Was the sync system the cure? What years does that work with, the advice from Eric? If cam and crank sensors are okay, then what do you check?
Jeep P1391 CMP or CKP Signal Intermittent Condition.
The P1391 was due to the intermittent CMP. The PCM uses the CMP to check the CKP. If they are not in time or one or the other is intermittent the PCM will throw the DTC P1391. PCM uses the CKP to keep the engine in time. I'm pretty sure this is because it is adjustable and the CMP is not.
On the I6 the CKP sits on top of the oil pump drive, just the way a distributor would have in older models. Adjustment is a similar procedure except you use a scan tool instead of a timing light.
PCM - Power Control Module
CKP - Crankshaft Position Sensor
CMP - Camshaft Position Sensor
DTC- Diagnostic Trouble Code
Actually a great lesson in tunnelvision.
How do? I don’t follow
@@SchrodingersBox Granted the existence of one problem is greater than than having two at the same time. However the symptoms being shown are indicative of numerous causes. Repeated fuel problems in the history is reason alone to check in that direction as well as for spark. As has been mentioned you did not verify actual fuel out of the injectors. I am a newbie at this but in my trade I sometimes get stuck in one avenue of diagnostics while ignoring something only to have my helper point it out to me.
I didnt verify fuel out of the injectors??? How do you explain those fuel trim numbers then and why isn’t fuel pressure higher than spec due to the restriction?
How can you say spark is possibly be a problem- what data indicates incomplete combustion and why isn’t fuel trim reflecting a no combustion condition? Why aren’t single misfires indicated? It makes no sense that this could be an injector restriction. What data do you see showing otherwise?
You say other variables are indicated based on the data but you don’t list them. For example why didn’t you say a bad O2 sensor a possible variable?Given the fuel trim numbers what are the other variables you suggest could explain those results and why do you think fuel delivery could be one despite the fuel trim data?
My original post about tunnelvision was based solely on several statements made by you in last minutes of the video. Something about getting stuck on something, chasing the starting problem and barking up the wrong tree. Maybe I was just reading too much into your statements. But where I come from that is known as tunnelvision. Since I barely know what you are talking about most of the time I had to rewatch both parts to even try to understand exactly what was going so youll have to excuse my ignore my ignorance.
Not a problem. This video- as all of my videos- are lessons in having “funnel vision” and NOT tunnel vision. By considering all variables and then dismissing any variables that cannot possibly be the issue based on rational analysis of the data, you funnel down to only variables that are possible and then rule them out til only one remains.
It is the exact opposite of either tunnel vision where you choose a variable- say spark - and chase that down despite the obvious fact spark cannot possibly be the issue and you change plugs, wires and coils and still don’t fix it. It is also opposed to “cannon vision” where you just shoot down everything equally instead of scientifically funneling to only possible causes. The parts cannon would have put endless parts like a MAF, MAP, plugs, wires, CTS, etc in this jeep.
When I first start the video you see I consider everything- MAF sensor, O2 sensors, ignition, fuel, compression, timing, vacuum leak…. but then when I collect data I am immediately able to funnel down that it is either a MAF issue or a fuel pressure issue. All other things are eliminated. It also cannot possibly be an injector issue or a spark issue- the data proves those are impossible. Then by focusing on just only those two possibilities, I was able to rule out that it is not a MAF issue- it has to be fuel pressure. The reading on the O2 sensors under WOT and the pressure test confirmed 100% it’s a fuel pump failing.
Not tunnel vision. Funnel vision.
dear matt . could tell me what is happening with my cruise car . i changed the crankshaft it was damaged but i have P0300,P0303 and P0304 no one knew whats the problem !!!! I replaced ( ignition coils,fuelpump,plugs) and( no leaks ) i checked the injectors no problem with them
any idea please I hope you will helpe me with this problem.
Yes I can tell you whats wrong. what data did you have that indicated the coils, pump and plugs were bad? Obviously you must have had fuel pressure and ignition voltage data indicating these were the problem- I need to see that data.
I though you would have checked the fuel pressure sooner on a no start but at the end you caught it good job
+gonz garr There was no logical indication to check fuel pressure. With normal fuel trims under load as indicated by the freeze frame, and only the cam crank sensor code- the logical evidence based conclusion leads to a cam and/or crank problem or correlation failure causing the starting as well as the misfiring,
Thats the beauty of this problem- The more you understand performance diagnostics, the more likely you are to bark up the wrong tree on this because of the unindicated problem sharing identical evidence with the indicated problem
you did a hell off a job finding the problem
+Schrodingers Box I strongly disagree with you on that and willing to argue with you if you desire. Forget the fuel pressure part; you missed the fuel part and that is what is bugging me. I am betting that if you did not have oscilloscope or scanner, you would have then went after fuel and immediately found the reason for no-start condition. Having the fancy tools at your disposal, you forgot the basics. Everybody makes mistakes.
12vgs8606 Nope, without a scope I would have still chased cam and crank first based on the evidence. Sorry bro but with all due respect you aren't "seeing it". Let me clarify:
1. Evidence that the hard start is related to Cam/Crank:
a. P0189 recurs even after clearing WITH CRANKING ONLY.
b. Long crank time
c. evidence was shown in video that no cam or crank signal causes a no start- P0189 is intermittent loss of cam signal
d. Timing advance 50 degrees from freeze frame
e. FUEL TRIMS NEUTRAL WITH NO STFT ADJUSTMENTS
Not to mention I was not even diagnosing a no or hard start- I was leveraging the hard start to get direction on the P0189.
Now lets look at evidence the hard start was fuel pressure related:
1. Long crank time.
Now- why on earth would a rational thinker based on that evidence possibly say "Hey moron- your problem is you have a cam or crank sensor issue AND you have a bad check valve in the fuel pump"??? What possible indication is there of there being two unrelated issues, with one being a bad check valve (remember- see point E above).
And why fuel pressure if you somehow knew there was another problem? Low compression causes random long crank times too but no one called that?
The fun part of this study was how an unrelated and actually contraindicated problem shared symptoms with the established problem from the code creating a "logic loop" that a diagnoistician following a logical evidence-based process would fall into.
Fundamentally what did noid light tell you? I think this is where we have very strong difference of opinion. Answer that question honestly, then I will continue from there.
Also tell me more about 50 degree timing advance and how that is relevant. Did you notice before and after timing advance?
More ornaments !!!!!! 😘 good job p!
+Corynne Jones OMG OK you earned them!!! Thanks for your help with this great video!!!
Not sure if these are one of that needs to have the tank dropped to change the pump, but is there a bunch of crap at the bottom of the tank that the pump is sucking up or clogging the filter which kills it or is it just a common thing with these Chrysler pumps
+argonian bilbo Exactly my thought too. Either way I will drop the tank and inspect for this.
fuel pump is very bad your test say that or fuel pressure regulator .and you almost done to fix this problem you very very very good tech thanks thanks for great learning video
+Mohamed Khalifa ; it could also be a fuel pump relay , when the relay gets hot , the relay closes and activates the fuel pump
You are right he has to check fuel pump relay but you know that very bad thing owner for this car spend money (1100$) for nothing
thanks for notes
thanks matt
+Chad Cohoon You're welcome Chad!
Smoking Video Matt. Please don't change a thing! You answered my question with regard to the drop out of the fuel injector pulse signal before I had an opportunity to ask it. A flooding condition would make perfect sense! When is the owner of that jeep going to fire the mechanic that over looked that crank sensor and left it like that for the replacement of a PCM and sensor. He should be watching your videos! Two thumbs up. Can't wait to see whats in his tank! Chuck
+Cobra Ninety Six The owner of the jeep did fire him-- actually went back and rubbed this video in his face lol.
But the fact is- the overwhelming vast majority of people still won't get it. He would watch this video and see me just wasting a bunch of time.
Well...., good for you!
I hope his physician is nothing like his mechanic. He may remove something he'd like to have before a comprehensive diagnosis.
2 thumbs up. ^5
ROTF I love the physician analogy- others have said the same- it's a perfect analogy because the diagnostic process is actually 100% identical.
Matt, is this happening during hot starts only or even during cold starts? If it's happening only during hot starts then this indicates that the fuel line cannot maintain pressure, so things like leaky injectors or a fuel line puncture would be likely culprits. If it's happening during cold starts as well then I have to question why the fuel pump isn't priming when the ignition is keyed to "On". Relay malfunction?
+Mohammad Zaid Khan It happens every time if more than 2 seconds passes. It is indicative of a bad check valve.
Since this is basically a Chrysler vehicle, check into the automatic shutdown relay (ASD) for problems with your fuel delivery.
+johnwrench4speed But why does it never shut down when running?
+Schrodingers Box It did when you disconnected the CKP. Additionally, from viewing the video when you were jiggling the CKP, when the engine went the roughest it was actually disrupting the ASD relay into shutdown rather than just a misfire as was the case at the other point in the jiggling.
Let me rephrase- now that the CKP issue is solved, what would cause the ASD to cause fuel delivery problems? Seems overwhelmingly obvious to me it's a bad check valve at fuel pump, not shut down problem.
+Schrodingers Box The ASD powers up/controls operation of fuel pump relay, injectors, coil primary, O2 sensor heaters and alternator. When there is a "hard start" problem with a Chrysler product it usually associated with a faulty ASD. So, even though you had injector and coil operation when cranking, a faulty ASD could still interrupt fuel flow because the fuel pump relay is not getting a continuous signal in order to operate the fuel pump. Regarding a KOEO fuel pump prime test (confirmed by a fuel pressure gauge), as you would see with GM and Ford products, if my memory serves me, you will not see this with a Chrysler product because the ASD times out after only two seconds. Finally, sure you could have a bad check valve at the fuel pump, but this doesn't necessarily explain how the fuel line can completely drain from the fuel rail back to the fuel tank so quickly and cause such a hard start.
Hi mate.Well done any way. One down one to go. Normally you would have an over pressurisation valve that returns petrol back to the tank. Could it be that the vale remains open, or partially open? ?dirt in the valve, so the system can't maintain pressure. Marcel.
+Marcel Timmers Yes there is a "check valve" that maintains pressureforprime and with engine off- clearly that is the cause of the crankng problem.
As soon as I saw spark and injector lights in part one I thought check fuel pressure too. Regardless, you did need to scope to fine the ckp sensor issue. This customer should let you check the fuel pump electrical circuit and put in a real mopar fuel pump. Cheap has become very expensive.
Hi Matt, What SnapOn scope is that? Is it a scan tool swell?
as far as buying a scope, what are the min spec requirements for auto use? I saw a few pocket ones in eBay for around $50 and might pick one up if it would meet the requirements. baby #2 due any second now, so budget is very tight. thanks
Your gonna need to replace the crank sensor ..once the felt is tore off from the flywheel u cant reuse it.. the crank sensor is the issue because its not tight
Without knowing more, I would have a bias in favor of some kind of chemical "pollutant" in the fuel tank, rather than some kind of "sediment" problem.
The filter in the tank is awfully fine, so if any "sediment" or physical material is getting into the actual mechanical pumping part of the pump, it would have to be awfully small. Of course it's possible, but my "intuition" tells me to look for some kind of chemical contaminant.
That was my thinking as I watched the vid, and as I read through most of the comments.
THEN, three quarters of the way down in the comments, Robert Higgins placed the link to the Thompson Fuel Systems video. I just watched the first few minutes, and wha'dya know, he mentions that there was a problem with the plastic in late '90's Chrysler or Jeep fuel tanks leading them to "dissolve", or "deteriorate", or something similar. He also mentioned something about putting E-85 in vehicles that are not engineered for it.
SO, if you don't find unusual amounts of sediment blocking the tank filter, I would say flush the tank very clean, put in a true Mopar brand pump (as others have suggested), and see what happens.
Tell eric to call flagship1 ny long island ..nassau county if he ever needs a computer ..they program them to the vehicle so its a plug n play
Shouldn't the fuel pressure come up as soon as the ignition is turned on?
+John Burke On most cars, yes- there is a 4 second prime that starts with the key in the on position. Not all cars have this though. But the main thing is how this car loses fuel pressure totally and immediately when engine is turned off- there is something wrong with the check valve for sure
+Schrodingers Box OK, thanks
Great diagnosis.
Why do you think it keeps having fuel pump problems?
+Shawn Lockard My opinion is there is probably sediment in the fuel tank that is never cleaned out. Since the starting problem is surely the check valve, I will surely have to drop the tank and I can verify the cause of the frequent failed pumps
+Schrodingers Box , you are probably correct, on flat rate you do not bother to check for that. That system only filters the fuel it uses so sediment could pass through the pump many times before it ends up in the filter. Resistance in pump wiring would be far more interesting to diagnose.
yes I don't remember if I choked voltage drop last time but for sure I will do that as well. I agree- no incentivefor a professional on flat rate or especially hourly to clean out a tank
+Schrodingers Box looking forward to your next video. Can your customer get their money back on the PCM? A new cam sensor would be semi reasonable if is a common failure and cheap but a new PCM is incompetence.
I always say the only thing worse than having a problem is having multiple problems. I was yelling at you in part 1 to put a fuel pressure gauge on it since the jeep had previous pump problems. Guess you didn't hear me...LoL. The cool part about not being sure how the system works is that you reasoned it out logically and finding the crank sensor "butchery" was a huge step toward the diagnosis. If I had to do work that way to make a living I would shoot myself in the head. {:-) I find that sometimes on a Chrysler a failing crank sensor will set a cam sensor code or vice versa because it senses a correlation problem between the crank and cam sensor but the PCM can't zoom in on the correct sensor. (Chrysler engineering)...BLAHHH.Can't wait for the fuel pressure issue diagnosis. Keep learning.
+wysetech2000 In a logical approach you have to go with the evidence. Fuel trim data indicated no fuel pressure problem and he recurrence of the code during cranking plus he misfire issue all indicated command for fuel and spark must be indicative of timing rather than fuel pressure. A lot of people don't understand this because they don't see the beauty of the logic circle created by two independent problems where the indicated symptom just so happens to superimpose the unindicated symptom. That is the point of the whole video but I don't think people see it.
Can you just replace the sensor??
20000 words and not bolt came out.
Sorry why would you replace the sensor?
Did you ever work on the Fuel pump problem? link?
The CKP sensor was obviously worked on. It is missing "A wire shield/router is attached to the sensor"
# 3 - WIRE SHIELD, and CKP sensor had been worked on or possibly removed, was a new #6 - PAPER SPACER installed or is the old one still there? This may need to be looked at. Found image of the shield at 5:00 of this video (I do not endorse the video but did find this image of the actual shield here to illustrate). ua-cam.com/video/7D0vUEDSwXo/v-deo.html
Couldn't find one of the spacer but #6 in this parts diagram is it. This should be replaced I think if the sensor is removed.
Image google - www.google.com/search?q=2004+jeep+grand+cherokee+crank+sensor&rlz=1C1_____enUS522US523&es_sm=122&tbm=isch&imgil=ckVSM0DzRM0lSM%253A%253BCkEdqCamUWJhLM%253Bhttp%25253A%25252F%25252Fwww.jeepz.com%25252Fforum%25252Fcherokee-commander-wagoneer-liberty%25252F27678-2004-grand-cherokee-4-0-cranks-but-will-not-start.html&source=iu&pf=m&fir=ckVSM0DzRM0lSM%253A%252CCkEdqCamUWJhLM%252C_&biw=1184&bih=580&usg=__joxSCXTWguyvAsS1pVEqOHAut2I%3D&ved=0CGQQyjdqFQoTCLeNjMj-6scCFdKOkgodhVYLMw&ei=A7HwVff_G9KdygSFra2YAw#imgrc=ckVSM0DzRM0lSM%3A&usg=__joxSCXTWguyvAsS1pVEqOHAut2I%3D
matt where did you get your labscope program for your laptop?
+larry mencke autoenginuity
Perhaps it was the very observation of fuel pressure that ultimately caused the low fuel pressure to become reality. In which case who could have ever suspected a condition that simultaneously was and was not? Schrodingers Fuel Rail.
+Fastest Caskets Lol well explained!!!
When you installed the CKPS did you have to find TDC??
No
Where's the double like button???????
+Corynne Jones Under my belt
what was the part about this Jeep was getting a fuel pump every year?
Exactly
Can you tell me what type of scan tool you were using for this vid ?
pretty sure on this one I used Auto Enginuity.
Hi Matt
What happened to my favorite FASTTEC method? Dump the Noid light it is for the birds! Did You notice in part 1 that the freezeframe data showed 50+degrees advance at 896RPM?
Greetings, Bernhard.
+Bernhard List FASTEC was not used because of overwhelming evidence that cam or crank signal was responsible and so I went with the evidence available until I finally excluded it.
+Schrodingers Box
Actually I do like Fasttec so much that I added one item and made it FASTTREC, the R standing for Reference Circuit and Electric Component because it can also stop a car from starting.
With me having still very little practical experience I could fix 3 cars already useing your systematic approach, so I will just stick to that.
Thanks Matt
Bernhard List Yeah the R may stand for "redundant" though lol- because a reference circuit will still cause either Fuel and/or Spark failure. The idea with "FASTEC" is these are "raw sources" of which the explanation for that missing source must be found.
i think i would replace the fuel filter first to solve the fuel pressure problem first (the fuel pressure regulator is part of the fuel filter)
+anita brodie Why? There is proper regulation of fuel pressure under load vs under idle. The fuel pressure regulator also does not control the static pressure.
Would resetting the Pcm not reset cam and crank ?
It would reset everything but fix nothing.
final diagnosis was fuel pressure but you said the 1391 still the only code. did u find out if they work together somehow to get the code I changed cam and crank but still get rough idle every other start up.
Why did you change the cam and crank sensors? Not sure I follow? You confirmed signal, ground and reference?
I got the same p1391. I read in some thread of jeeps having issues with the cam/ crank. drove the cat with no issues for a day then light came back on. all I have is a volt meter to check the ref voltage and it was fine. on the 4.7 u have to remove the stater to get to the crank so it was tough for me to try to check for v drop.
Luis Contreras Lots of things can cause a P1391- and just because a thread says what the issue was- first, it doesn't mean that's the same cause of your issue and second, they were lying anyway because they don't know what they're talking about either.
As it stands you need to verify signal, ground and reference- anything else you do is a guess at best and waste of time and money at worst.
I usually save time by just doing a cam and crank sensor bypass to verify circuit integrity and if the bypass fails then I narrow to the side of circuit with the fault.
Luis Contreras have you checked ignition timing 1391 usually caused by crank sensor shaft/oil pump drive off time a few degrees. Loosen hold down rotate a lil till sync signal in spec I can get u specs if needed