Paul, If the fuel trims are normal then the plugged cat is the rear one. This is because the MAF correctly measures the incoming air. Then the air is equally distributed bank to bank. If the fuel trims are negative on one bank and positive on the other bank the same amount. Example -22 total fuel trim on bank 1 and 22 total fuel trim on bank 2. Then only one bank is plugged. This is because the engine is now drawing in less air, due to one of the banks cat being plugged. The MAF reads the incoming air correctly, but then the unrestricted bank takes the majority of the air and the restricted side does not, but the fuel is still being added by the injectors on the restricted side. This means the restricted side is getting to much fuel for the amount of air it has available. This means the side with the negative fuel trims is the restricted bank. Hope this info helps.
Thank you! Sometimes I forget to add the links for multi-part series. I take it I did on this one? Appreciate your feedback and if you ever find one missing, just comment about it, I see every single one. Thanks again
I’m glad this popped up. Haven’t seen this one. Great job of explaining the in cylinder. I was looking in your book a while back hoping there would be a pressure transducer chapter. Thanks for the excellent content as usual Paul! Keep on being a badass 🤘
This vid is definitely in the top 20% of your collection. Seeing the pressure pulsations to that level of detail and resolution is amazing. The moment you rev'd the engine on the first bank test I knew what the problem was (like you did). I don't have Premium, so I won't see the follow-up video. Also, in a shop environment, a tech could print a screen shot of that waveform and provide it to the customer, to show the proof that the exhaust is plugged. One of the many benefits of computerized testing. Knowing if the second bank tested has a bad cat would be a little tougher call, but fortunately both pre-cats get replaced together because they are all part of one Y pipe assembly as you said, so that fairly tough call on the second pre-cat isn't one that necessarily needs to be made. Even though this video would normally be in the Premium area only, I humbly suggest shooting a follow-up after the exhaust is fixed, so that those of us without Premium can still see what the outcome was. That pressure gauge is SWEET, but at 750 clams, not something I'll be buying in this lifetime (but for a Pro it would be worth it, but not for me as an amateur). By the way, my brother has a 1997 Ford F-150 4.6L V-8. I removed the driver's side O2 to test for a plugged cat, because he has had a massive vacuum leak for a long time, (cracked intake manifold lower section-plastic-) along with massive lean misfires, but lots of fuel going through, because the computer is dumping in fuel, but can't bring the mixture into a combustible range. Anyway, the gauge measured only .1 to .2 psi of back pressure, even at higher rev's. It was your video's that explained proper exhaust back pressures that taught me how to do that, and to know the his cat's are OK. Thanks Paul
Great use of a scope you are really pulling the full potential out of it You are right about a high back pressure on the oneside but at the beginning of the video you answered your own question That vehicle was no EGR so the cam profile is made to have a little different scavenging characteristics Not uncommon to see pressure (in cylinder) of around 41.0 inHG which is 1.5 psi at high idle would be Considerated good maybe next time try using the scope on the vacuum side not only will you see low vacuum but you will get spikes in the overlap on the intake stroke when I do it I trigger off the cam #1 TDC on a v6 or 8 with cats on both exhaust manifold You can see how one side will effect the other and if you really what to see something look at the crank signal and compare the HZ on companion cylinders You will see the side with a clogged cat slowing down the power stroke on the opposite side grant it it’s a small variation but fun to see I showed a guy who does a lot of after market tuning setups (not my thing) that and how to balance the exhaust system with proper placement of an X pipe
Once upon a time, when i was a dealer tech(Opel), 90% of plugged exhaust cases where from faulty rear muffler. 50% of cases diagnosis was easy, there was a squirrel(insulation fibers) coming out from tail pipe. So it´s not always cat-problem.
The only plugged muffler I've seen in 30 years as a tech was from pieces of the melted cat that got lodged downstream in the muffler. But agree, always and never are terms to be used cautiously
Those were late 80´s-90´s certain models. I guess it was a problem in the muffler desing. One other case come in my mind: Couple of years ago in the shop came quite new wolksvagen. Its exhaust was plugged from ice :) Winter, short driving, so water from exhaust gases never got a chance to evaporate. Temperature was around 0° F few weeks.
Thanks for this interesting analysis Paul; what about measuring the vacuum pressure from intake using the pico or even a pressure gauge to detect a plug exhaust?
Another very good video , it shore would have been great to have seen one cylinder pressure transducer per bank at the same time and two firstlook engine diagnostic pulse sensors one at the intake manifold and the next one in the tailpipe, very advanced diagnostics and thank you again.
Per ford manual they give a max back pressure spec, for example 2005 f150 5.4l. Should not exceed 8 psi per cat measured at up stream o2's. just have to deal with it and remove o2 for best accuracy. I do like your test method in this video. Great job. It's a delema to determine if the last cat is bad. Replace as needed and road test. Communication updates with the customer is key for this situation. Your data is all you have.
Thanks brother! This was in my spam box because of the link. It automatically puts them in there. I really appreciate you pointing this out. A complaint has been filed and it will be taken down. Anything I can do for you as a thank you? Want a copy of my eBook?
Thank you Paul. I already have access to your eBook Engine Performance Diagnostic through bookguardpro.com as I bought membership for reading it. Very good book by the way. And yes, I would like to grab my hands on the printed version as I like to take a look on it from time to time Kind regards
Thanks Paul getting back with me on the Dodge pickup it's usually baked 5 minutes after you get going sometimes when you're at a red light but I want to try cut off but most time it's not most of the time it's going down the road after you take off and it don't do it all the time might be twice a month thanks Paul I know you're busy and I love you videos
what would you do on a vehicle such as a Ford Escape where there is an electronic EGR and no access to the rear spark plugs? The O2 is also a pain to access on it.
This is great stuff! It's easy to understand. But being able to REMEMBER it with all the other stuff you need to know, is the real challenge! Too bad we couldn't just plug our numbers into a computer program and have it spit out a list of possible CAUSES!
In your explanation, you see in the intake stroke that the pressure goes out of the cylinder into the Intake manifold. There is a chance, in some engines or if the cat is completely molten shut, that you see exhaust gas coming out of the throttle body. I had it on the Ford Escape 3.0 of a friends wife and he told me "that's just from a misfire at the wrong time". In newer engines, that's so wrong, you can't go more wrong because the spark timing is sensor / computer controlled. After 2 weeks, I made the call it has something to do with the exhaust (again) and I was right. 3rd cat was molten shut, car was a crank - no start, and after emptying the cat it was ok again. Some time later we change it, was not easy to get this thing with the right connections. But if you have the problem, that the exhaust is completely clogged up and you have a no start: Remove one sparkplug and try it again. It will run because the pressure equalization will be possible with an open cylinder.
Paul,how you ever use fuel trim as a guide direction for plug exhaust? a was in a class where the teacher said for example if you have in bank 1, 12 positive and -12 on bank 2. classic fuel trim numbers of plug exhaust on v type engines . Personally I have not seen it yet, but I hope I can get one soon.
I have not, but I have also recently (from a subscriber on my premium channel) learned about this same thing. wish I had this ranger back to play with it. The student wrecked it! I am so mad. No follow up will be possible on this vehicle.
I've seen trims used to locate a plugged exhaust on dual bank, one cat per bank engines, because one bank is drawing in less air than the other bank. I believe one bank should show an extreme opposite of the other such as -15% LTFT bank 1, +15% LTFT bank 2. Something close to it. You're correct. I like using a typical gauge like Paul used to, and if it's a Ford then using the DPFE is just as good and easier. I do think, because of it's speed, taking a quick look at the LTFTs if you suspect a restricted exhaust on these engines can provide more direction and confidence towards checking for a restricted exhaust. Cheers
Hey danner don't know if u showed this in part two but a vacuum gauge hooked to the intake could point to a plugged converter the reading on the gauge would be less vacuum at 2500 to 3000 rpm than at idle due to it not being able to breath
SUBSTANTIAL Sir ScannerDanner rillian👏 👍 👌 Thank you ,take care and have a great day 👍 Good Morning Sir ScannerDanner From Nick Ayivor from London England UK 🇬🇧 The 🌞 is out but 🥶 day
Hello Paul, I have a problem 2006 Ford F150 5.4L lack of power/misfire #7 cylinder. This truck has a fairly new engine, ECM, wiring harness(I can see a lot of black tape and splices), rack, intermediate shaft. Someone has dumped a ton of money into this truck. Might I add, this truck was bought at an auction and my doesn't want to put a whole lot of diagnosis time into it. I'm the 3rd tech in my shop to touch this vehicle. They, not me, have thrown an injector & coil, checked fuel pressure which is good, dropped exhaust to verify clogged exhaust, so this eliminated some testing for me... So I test drove watching my O2 sensors at WOT and noticed they were all rich with no power. I've current ramped the coil and looked at injector waveforms with my Vantage pro and compared with known good cylinders at idle and snap, which look good. Cylinder #7 has about 140 psi compared to cyl #1 170 psi opposite bank. Could this fairly new engine be junk or am I chasing a air delivery problem? Paul, any help would be appreciated.
I am going to get you a book and I look at your videos every night from like 9 at night till 3 in the morning I also try to fit Eric the Car Guy in once in awhile I like him too
Paul , i too have the "Unable to view in your country" message but i think it's purely UA-cam vetting the post before they release it for me to view . I think some others may come across this message also when trying to view it . Like you say best thing to do if already subscribing is to give it 12-24 hrs and see if able to view there after . Tim :)
I got a 98 cadillac eldorado , Bank 2 is running 25 on Long term Bank 1 is running 5 on the long term. I thought it was the intake manifold cause i smoked it and some smoke leaked out of the intake. I replaced the intake gasket and come to find out the smoke was coming out of a backfire "Flap" so i had no leak to begin with, while i was doing this i swapped the injectors from bank 2 to bank 1 and vise versa incase it was an injector issue. My o2 sensors seem to respond together when i introduce propane into the intake, i also checked for vac Leaks with water / propane and eltrical cleaner. and no change in shortterm/longterm. @ idle. The only other thing i can think of is that i have a exhaust manifold thats leaking , any insight would be greatly appriciated , Thanks
hey there, Paul if I need to check a Nissan whit pressure transducer and I cant remove the spark plug cause the intake is on top of ignition coil, is possible to remove the ho2s and take it from this point, do you recommend it ??
Paul I have a question I have a 2000 Dodge Ram 1500 5.9 every once in awhile when I first started up and get moving it don't act like it's getting fuel and it backfires through the intake it only does it for a couple minutes and a finally take off like a striped ape it does not do this all the time and there is no codes set I know I have good fuel pressure in the shop seems like I can't get it to mess up in the shop I have to be driving I was also thinking about changing cam sensor but I don't want to be a
Hi Paul, great video. I have a WPS 500 and have not considered using for in cylinder back pressure testing as I normally drill a small hole & weld it later. One thing though, have you struck back pressure in the exhaust manifold (before the turbo)being higher than normal for turboed engines? What are your thoughts. Jamie. New Zealand.
scannerdanner what is the best way to adjust a carb? i dont know this old stuff maybe you can help. its a carter series i think thats the same as an edelbrock.
Set your mixture screws to the FIRST point of your highest rpm or vacuum. By first point I am saying you will get to a point where additional turns do not increase it anymore, you're just dumping unnecessary fuel now. The first point of your highest rpm (can use your ear) on each mixture screw. Then when your happy, if rpm is now too high, set base idle screw and then redo the whole thing again.
reason i ask is because when im in park doing a dead rev it revs real nice but if i get on the gas to get on a highway it has a dead spot hesitation. figured id ask the pro. could be timing to though. is it true you can time an engine with a vaccuum gauge? 72 dodge dart 318
Paul, great video!!!! Paul did you have the schrader valve removed from the transducer hose? Would it make a difference in the waveform readings with or with out being installed in the transducer hose?
There is never a schrader valve in a compression hose when using a scope and psi transducer. You don't want to trap any psi in the hose, ever. It would alter the entire waveform. Make sense?
I did not think their was, and I only asked due to someone stating they did not have the schrader valve installed in the compression hose and they were using a wps500 and I also agree it would give an incorrect outcome/diagnosis. Just asking to verify that is all. Thanks again for your hard work and reply!!!!!!!@@ScannerDanner
When the primary winding in the coil charges it induces a magnetic field in the iron core of the coil which transfers to the secondary winding and causes a bunch of electrons to build up, so there are a whole bunch of electrons sitting there, then when the primary coil turns off, the magnetic charge or field collapses, this causes the built up electrons in the secondary winding to MOVE quickly, they have to go to ground somehow and they will find a way, normally through the wire to the plug and jumping the plugs gap is the path of least resistance, if you disconnect the plug wire at the coil and start the engine you can normally observe the spark jumping out of the coil terminal and striking the coil somewhere nearby, sometimes you wont see it because it is happeneing internally, either way this is bad so dont do it, the spark is finding ground where it shouldn't be sending that kind of voltage. The danger and the reason you must give the spark a path to ground away fron the coil is that that the high voltage spark will damage sensitive componenets when it backfeeds into the coil primary side, some coils have the sensitive components inside them, most coils are triggered with a negative switching to the primary side, so the spark will find its way back to the Ignition Module or even worse the PCM and fry the Coil Driver Circuit. Long story short, there is a chance that the spark will backfeed into the Ignition Module or Engine Computer and destroy the sensitive circuits that control the coil.
Time frame of the video please. Thanks! Most likely this is a MAF engine where what is being measured by the MAF (airflow), is not balanced from bank to bank like it should be. So you're going to have mixture issues on both sides when one side is plugged.
Hi Paul I had one that when you take it on a road test or revved it high the exhaust prior to the blocked exhaust glowed red hot if that's any help...what about looseneing flange coupling instead of drilling hole, to let pressure out Fred uk
ScannerDanner Hi Paul, I;m afraid that one went over my head, never had any problems with salt, do you mean it catches fire?, don't use it in summer anyway, we do use it in the winder, could get it hot stationary in your workshop and give it a good rev...I accidently had one running and the front pipe stated glowing red, it was unintentional...turned out to be a blocked cat...I have driven them up the road with the coupling flange loose to let the pressure out, never had any trouble personally Fred in England..
@@ScannerDanner so.. using VE test..and graphing the 02 and fuel trims for both banks...if the VE test fails and the 02 is rich for both banks "it's not fuel pressure or the MAF sensor" now fuel trims Will point you to the clogged bank ...😎
Hello Scanner, I purchased your E Book recently. I like it a lot, as it is an easy read. Question, do you have any suggestion for reducing noise using the PICO orange handle COP probe? I get a lot of noise on the screen. Any ideas? Do you think the new PICO scope is worth the upgrade? Thanks for what you do!
Paul,I have a question regarding your preliminary conclusion that directed you towards a plugged exhaust : you look at the O2s on each bank at WOT and see they are rich,thus eliminating the dirty MAF possibility. My confusion comes because I thought at WOT the fuel trims go in OPEN loop and the computer is not using O2 readings. Do you record those 800mV readings right before it goes in OPEN loop? Thanks!
i seen the one you have on a old school impala now like the o2 sensor reading trick under wot. i always use that now for a low power complaint! what technique do you use to find a problem for a continuos blowing fuse?
Not sure what Paul uses but there is a tool called a short finder that works real neat for finding shorts. (Mine is badged Lisle but there are a bunch of "brands") www.amazon.com/Tool-Aid-25100-Short-Tester/dp/B000RFLR0U It's basically a self resetting circuit breaker and an inductive meter. (I picked up a few in different values for lower/higher loads) You connect the breaker in place of the fuse. It will trip/reset cycle. Then you run the meter along the harness. As you follow the wires the meter will oscillate in time with the breaker. When you get to or pass the short the meter will stop. I believe power probe makes one that uses RF to trace the circuit as well.
Hmm, very interesting! Out of curiosity, are the compression stroke numbers normal for a running engine? I was seeing 60-75 PSI at peak compression on your scope there, which is about half of what I would expect to see doing a cranking compression test. Having never analyzed a running engine before, I'm curious if this is a normal number, or if it's another sign of a restricted exhaust (can't exhale, can't inhale).
Running compression numbers (idle and no load higher rpm) will always be lower than cranking (significantly lower). This is due in part from the almost fully closed throttle plate (high manifold vacuum) and the shortened time of intake valve opening (compared to cranking rpm)
ScannerDanner, my PRO virtual teacher, i really apreashiate all your great clips. i have a humble request: if you can do a video clip about the Accelerator Pedal Position Sensor. i realy have a tough time with it. thanks allot and god bless. Adi from israel.
Nevermind.......I HAVE to learn to read all the comments before I post my own. I just saw the note that said the car was wrecked and the "after" vid would not be available. Bummer.
If the CAT is doing its job, shouldn`t be a difference between the 2 readings of the O2 sensors? The upstream one should bounce, but the downstream one shouldn`t be close to a constant reading? So if the CAT is plugged, than the reading should be the same, because the CAT is not doing it`s job.
I've never had an issue with it. Just have to know to disconnect vacuum line on EGR to prevent the valve from opening and affecting your measurement. Is there something else I am not considering or missing? Thanks!.
Hey danner don't know if u showed this in part two but a vacuum gauge hooked to the intake could point to a plugged converter the reading on the gauge would be less vacuum at 2500 to 3000 rpm than at idle due to it not being able to breath
eight years and still very informative , thanks as always
Paul, If the fuel trims are normal then the plugged cat is the rear one. This is because the MAF correctly measures the incoming air. Then the air is equally distributed bank to bank. If the fuel trims are negative on one bank and positive on the other bank the same amount. Example -22 total fuel trim on bank 1 and 22 total fuel trim on bank 2. Then only one bank is plugged. This is because the engine is now drawing in less air, due to one of the banks cat being plugged. The MAF reads the incoming air correctly, but then the unrestricted bank takes the majority of the air and the restricted side does not, but the fuel is still being added by the injectors on the restricted side. This means the restricted side is getting to much fuel for the amount of air it has available. This means the side with the negative fuel trims is the restricted bank. Hope this info helps.
Great tip! I meant to check the trim numbers and never did. I'm actually upset now that I didn't. Makes perfect sense. Thanks so much
ScannerDanner.. you can read them at 3:15... LTFT#1 is +20% and LTFT#2 is -22%
EXCELLENT
Yeh science!
I am grateful to you, Paul, for publishing these videos here for free. Everything I know I learnt for you.
🙌🏻
So many multi-part videos don’t link to the others. Thank you for doing this!
Off to watch part 2! Man I love your videos!
Thank you! Sometimes I forget to add the links for multi-part series. I take it I did on this one? Appreciate your feedback and if you ever find one missing, just comment about it, I see every single one. Thanks again
I’m glad this popped up. Haven’t seen this one. Great job of explaining the in cylinder. I was looking in your book a while back hoping there would be a pressure transducer chapter. Thanks for the excellent content as usual Paul! Keep on being a badass 🤘
This vid is definitely in the top 20% of your collection. Seeing the pressure pulsations to that level of detail and resolution is amazing. The moment you rev'd the engine on the first bank test I knew what the problem was (like you did). I don't have Premium, so I won't see the follow-up video.
Also, in a shop environment, a tech could print a screen shot of that waveform and provide it to the customer, to show the proof that the exhaust is plugged. One of the many benefits of computerized testing.
Knowing if the second bank tested has a bad cat would be a little tougher call, but fortunately both pre-cats get replaced together because they are all part of one Y pipe assembly as you said, so that fairly tough call on the second pre-cat isn't one that necessarily needs to be made.
Even though this video would normally be in the Premium area only, I humbly suggest shooting a follow-up after the exhaust is fixed, so that those of us without Premium can still see what the outcome was.
That pressure gauge is SWEET, but at 750 clams, not something I'll be buying in this lifetime (but for a Pro it would be worth it, but not for me as an amateur).
By the way, my brother has a 1997 Ford F-150 4.6L V-8. I removed the driver's side O2 to test for a plugged cat, because he has had a massive vacuum leak for a long time, (cracked intake manifold lower section-plastic-) along with massive lean misfires, but lots of fuel going through, because the computer is dumping in fuel, but can't bring the mixture into a combustible range. Anyway, the gauge measured only .1 to .2 psi of back pressure, even at higher rev's. It was your video's that explained proper exhaust back pressures that taught me how to do that, and to know the his cat's are OK.
Thanks Paul
👍 thank you! You're an awesome instructor Paul. I teach machinist classes as side job and really like your style. Very fortunate students.
Great use of a scope you are really pulling the full potential out of it
You are right about a high back pressure on the oneside but at the beginning of the video you answered your own question
That vehicle was no EGR so the cam profile is made to have a little different scavenging characteristics Not uncommon to see pressure (in cylinder) of around 41.0 inHG which is 1.5 psi at high idle would be Considerated good maybe next time try using the scope on the vacuum side not only will you see low vacuum but you will get spikes in the overlap on the intake stroke when I do it I trigger off the cam #1 TDC on a v6 or 8 with cats on both exhaust manifold You can see how one side will effect the other and if you really what to see something look at the crank signal and compare the HZ on companion cylinders You will see the side with a clogged cat slowing down the power stroke on the opposite side grant it it’s a small variation but fun to see I showed a guy who does a lot of after market tuning setups (not my thing) that and how to balance the exhaust system with proper placement of an X pipe
Once upon a time, when i was a dealer tech(Opel), 90% of plugged exhaust cases where from faulty rear muffler. 50% of cases diagnosis was easy, there was a squirrel(insulation fibers) coming out from tail pipe. So it´s not always cat-problem.
The only plugged muffler I've seen in 30 years as a tech was from pieces of the melted cat that got lodged downstream in the muffler. But agree, always and never are terms to be used cautiously
Those were late 80´s-90´s certain models. I guess it was a problem in the muffler desing. One other case come in my mind: Couple of years ago in the shop came quite new wolksvagen. Its exhaust was plugged from ice :) Winter, short driving, so water from exhaust gases never got a chance to evaporate. Temperature was around 0° F few weeks.
Thanks for this interesting analysis Paul; what about measuring the vacuum pressure from intake using the pico or even a pressure gauge to detect a plug exhaust?
Another very good video , it shore would have been great to have seen one cylinder pressure transducer per bank at the same time and two firstlook engine diagnostic pulse sensors one at the intake manifold and the next one in the tailpipe, very advanced diagnostics and thank you again.
Another great video. Thank you
Per ford manual they give a max back pressure spec, for example 2005 f150 5.4l. Should not exceed 8 psi per cat measured at up stream o2's. just have to deal with it and remove o2 for best accuracy. I do like your test method in this video. Great job. It's a delema to determine if the last cat is bad. Replace as needed and road test. Communication updates with the customer is key for this situation. Your data is all you have.
That is an under load spec
Thanks brother! This was in my spam box because of the link. It automatically puts them in there. I really appreciate you pointing this out. A complaint has been filed and it will be taken down.
Anything I can do for you as a thank you? Want a copy of my eBook?
Thank you Paul. I already have access to your eBook Engine Performance
Diagnostic through bookguardpro.com as I bought membership for reading
it.
Very good book by the way. And yes, I would like to grab my
hands on the printed version as I like to take a look on it from time to
time
Kind regards
Email me at paul@scannerdanner.com
Thanks Paul getting back with me on the Dodge pickup it's usually baked 5 minutes after you get going sometimes when you're at a red light but I want to try cut off but most time it's not most of the time it's going down the road after you take off and it don't do it all the time might be twice a month thanks Paul I know you're busy and I love you videos
Stay in the same thread Charles, I have no idea what you're talking about otherwise. Thanks!
what would you do on a vehicle such as a Ford Escape where there is an electronic EGR and no access to the rear spark plugs? The O2 is also a pain to access on it.
Another good one. Can't forget to have the exhaust shop check the muffler for cat debris. Maybe you mentioned that in your part 2. Thanks again.
This is great stuff! It's easy to understand. But being able to REMEMBER it with all the other stuff you need to know, is the real challenge! Too bad we couldn't just plug our numbers into a computer program and have it spit out a list of possible CAUSES!
In your explanation, you see in the intake stroke that the pressure goes out of the cylinder into the Intake manifold. There is a chance, in some engines or if the cat is completely molten shut, that you see exhaust gas coming out of the throttle body. I had it on the Ford Escape 3.0 of a friends wife and he told me "that's just from a misfire at the wrong time". In newer engines, that's so wrong, you can't go more wrong because the spark timing is sensor / computer controlled.
After 2 weeks, I made the call it has something to do with the exhaust (again) and I was right. 3rd cat was molten shut, car was a crank - no start, and after emptying the cat it was ok again. Some time later we change it, was not easy to get this thing with the right connections.
But if you have the problem, that the exhaust is completely clogged up and you have a no start: Remove one sparkplug and try it again. It will run because the pressure equalization will be possible with an open cylinder.
Paul,how you ever use fuel trim as a guide direction for plug exhaust? a was in a class where the teacher said for example if you have in bank 1, 12 positive and -12 on bank 2. classic fuel trim numbers of plug exhaust on v type engines . Personally I have not seen it yet, but I hope I can get one soon.
I have not, but I have also recently (from a subscriber on my premium channel) learned about this same thing.
wish I had this ranger back to play with it. The student wrecked it! I am so mad. No follow up will be possible on this vehicle.
I've seen trims used to locate a plugged exhaust on dual bank, one cat per bank engines, because one bank is drawing in less air than the other bank. I believe one bank should show an extreme opposite of the other such as -15% LTFT bank 1, +15% LTFT bank 2. Something close to it. You're correct. I like using a typical gauge like Paul used to, and if it's a Ford then using the DPFE is just as good and easier. I do think, because of it's speed, taking a quick look at the LTFTs if you suspect a restricted exhaust on these engines can provide more direction and confidence towards checking for a restricted exhaust. Cheers
Yeah, I go with replacing all the cats too when there's 3 or more cats on a car myself. I learned that the hard way on a Hyundai Santa Fe.
Fantastic as always.
Hey danner don't know if u showed this in part two but a vacuum gauge hooked to the intake could point to a plugged converter the reading on the gauge would be less vacuum at 2500 to 3000 rpm than at idle due to it not being able to breath
I would go with which o2 sensor had higher MVs. Which both was reading rich. Which means both banks was clogged right?
Calculated load or volumetric efficiency pids would help prove or disprove a restricted exhaust.
A quick point with a laser temp guage before and after cat gives a good indication of a blocked cat remember temp rises with pressure
SUBSTANTIAL Sir ScannerDanner rillian👏 👍 👌 Thank you ,take care and have a great day 👍 Good Morning
Sir ScannerDanner
From Nick Ayivor from London England UK 🇬🇧
The 🌞 is out but 🥶 day
Nice problem-solving video! Great!
Hello Paul,
I have a problem 2006 Ford F150 5.4L lack of power/misfire #7 cylinder. This truck has a fairly new engine, ECM, wiring harness(I can see a lot of black tape and splices), rack, intermediate shaft. Someone has dumped a ton of money into this truck. Might I add, this truck was bought at an auction and my doesn't want to put a whole lot of diagnosis time into it. I'm the 3rd tech in my shop to touch this vehicle. They, not me, have thrown an injector & coil, checked fuel pressure which is good, dropped exhaust to verify clogged exhaust, so this eliminated some testing for me... So I test drove watching my O2 sensors at WOT and noticed they were all rich with no power. I've current ramped the coil and looked at injector waveforms with my Vantage pro and compared with known good cylinders at idle and snap, which look good. Cylinder #7 has about 140 psi compared to cyl #1 170 psi opposite bank. Could this fairly new engine be junk or am I chasing a air delivery problem? Paul, any help would be appreciated.
I am going to get you a book and I look at your videos every night from like 9 at night till 3 in the morning I also try to fit Eric the Car Guy in once in awhile I like him too
Thank you Charles!
Forget Eric the car guy. Bottom of the barrel
Haha ... just tried it one more time for luck , and i'm now able to watch it :D
Literally 1 min between .
Paul , i too have the "Unable to view in your country" message but i think it's purely UA-cam vetting the post before they release it for me to view . I think some others may come across this message also when trying to view it .
Like you say best thing to do if already subscribing is to give it 12-24 hrs and see if able to view there after . Tim :)
youre hooking me Danner now I must subscribe to the primo channel As my exhaust makes a whistle beyond 3000 rpm WOT Thanks for youre fine work Amigo.
Paul do you ever use a noid light to check for injector pulse
rarely but I have a lesson on this right here on youtube ua-cam.com/video/6vIcu3NVfcU/v-deo.html
Part 2 says it's not available in my country (Canada) and I'm a subscriber
It will be, just uploaded it. It takes a few to process
Ahhh ok. Thanks Danner
Do u think the pressure transducer should be installed on the companion cylinder even if it was a log style manifold or a header style?
you just need to be aware of the variables with manifold psi changes based on where your transducer is mounted
I got a 98 cadillac eldorado , Bank 2 is running 25 on Long term Bank 1 is running 5 on the long term. I thought it was the intake manifold cause i smoked it and some smoke leaked out of the intake. I replaced the intake gasket and come to find out the smoke was coming out of a backfire "Flap" so i had no leak to begin with, while i was doing this i swapped the injectors from bank 2 to bank 1 and vise versa incase it was an injector issue. My o2 sensors seem to respond together when i introduce propane into the intake, i also checked for vac Leaks with water / propane and eltrical cleaner. and no change in shortterm/longterm. @ idle. The only other thing i can think of is that i have a exhaust manifold thats leaking , any insight would be greatly appriciated , Thanks
hey there, Paul if I need to check a Nissan whit pressure transducer and I cant remove the spark plug cause the intake is on top of ignition coil, is possible to remove the ho2s and take it from this point, do you recommend it ??
For sure. Remove the upstream O2 and just adapt a simple vacuum psi gauge. Or your psi transducer would work too
@@ScannerDanner do I have to remove the scharder valve?
how common is it for regular mid size shops to have all of these electronic capabilities , such as the pico verus ect.?
Great video.
Wouldn't it trigger a p0420?
Wouldn't the 02s2 will show symptoms of a bad cat?
Paul I have a question I have a 2000 Dodge Ram 1500 5.9 every once in awhile when I first started up and get moving it don't act like it's getting fuel and it backfires through the intake it only does it for a couple minutes and a finally take off like a striped ape it does not do this all the time and there is no codes set I know I have good fuel pressure in the shop seems like I can't get it to mess up in the shop I have to be driving I was also thinking about changing cam sensor but I don't want to be a
How long after start up? Immediately or after a minute or two?
And vacuum ?
Hi Paul, great video. I have a WPS 500 and have not considered using for in cylinder back pressure testing as I normally drill a small hole & weld it later.
One thing though, have you struck back pressure in the exhaust manifold (before the turbo)being higher than normal for turboed engines?
What are your thoughts.
Jamie.
New Zealand.
Good question. Unfortunately I have not, still learning myself with this tool. Lots of variables.
scannerdanner what is the best way to adjust a carb? i dont know this old stuff maybe you can help. its a carter series i think thats the same as an edelbrock.
Set your mixture screws to the FIRST point of your highest rpm or vacuum. By first point I am saying you will get to a point where additional turns do not increase it anymore, you're just dumping unnecessary fuel now. The first point of your highest rpm (can use your ear) on each mixture screw. Then when your happy, if rpm is now too high, set base idle screw and then redo the whole thing again.
reason i ask is because when im in park doing a dead rev it revs real nice but if i get on the gas to get on a highway it has a dead spot hesitation. figured id ask the pro. could be timing to though. is it true you can time an engine with a vaccuum gauge? 72 dodge dart 318
Then it's not the mixture screws. Focus on the secondary circuit and accelerator pump.
ok thanks get james danner to start uploading vids again
Paul, great video!!!! Paul did you have the schrader valve removed from the transducer hose? Would it make a difference in the waveform readings with or with out being installed in the transducer hose?
There is never a schrader valve in a compression hose when using a scope and psi transducer. You don't want to trap any psi in the hose, ever. It would alter the entire waveform. Make sense?
I did not think their was, and I only asked due to someone stating they did not have the schrader valve installed in the compression hose and they were using a wps500 and I also agree it would give an incorrect outcome/diagnosis. Just asking to verify that is all. Thanks again for your hard work and reply!!!!!!!@@ScannerDanner
No problem Kevin, I wasn't judging. Thought it was a great question actually.
Hot damn 🔥 keep up the fine work there!!!!
Just a question.
Can you tell me why an unconneceted plug wire can overload the ignition coil while the engine is running?
Thanks.
When the primary winding in the coil charges it induces a magnetic field in the iron core of the coil which transfers to the secondary winding and causes a bunch of electrons to build up, so there are a whole bunch of electrons sitting there, then when the primary coil turns off, the magnetic charge or field collapses, this causes the built up electrons in the secondary winding to MOVE quickly, they have to go to ground somehow and they will find a way, normally through the wire to the plug and jumping the plugs gap is the path of least resistance, if you disconnect the plug wire at the coil and start the engine you can normally observe the spark jumping out of the coil terminal and striking the coil somewhere nearby, sometimes you wont see it because it is happeneing internally, either way this is bad so dont do it, the spark is finding ground where it shouldn't be sending that kind of voltage. The danger and the reason you must give the spark a path to ground away fron the coil is that that the high voltage spark will damage sensitive componenets when it backfeeds into the coil primary side, some coils have the sensitive components inside them, most coils are triggered with a negative switching to the primary side, so the spark will find its way back to the Ignition Module or even worse the PCM and fry the Coil Driver Circuit. Long story short, there is a chance that the spark will backfeed into the Ignition Module or Engine Computer and destroy the sensitive circuits that control the coil.
Well said, thanks. Then there is the issue with my scope and psi transducer. Don't want it going there either :)
ScannerDanner.......Yeah that too.....haha!
When you pull a plug lead off the coil voltage hits the roof, I have had 51 kv coming out of a coil
Is there an option for this test using a snap on verus pro ?
with the correct pressure transducer yes
hi master, could you explain why LFTRIM is high? Thanks!
Time frame of the video please. Thanks!
Most likely this is a MAF engine where what is being measured by the MAF (airflow), is not balanced from bank to bank like it should be. So you're going to have mixture issues on both sides when one side is plugged.
@@ScannerDanner ah now i understand it, thank you so much master! love you! i have not noticed it had two banks :D.
Hi Paul I had one that when you take it on a road test or revved it high the exhaust prior to the blocked exhaust glowed red hot if that's any help...what about looseneing flange coupling instead of drilling hole, to let pressure out Fred uk
Tom, you must live somewhere were they don't use road salt in the winter. Not possible to do that here my friend.
ScannerDanner Hi Paul, I;m afraid that one went over my head, never had any problems with salt, do you mean it catches fire?, don't use it in summer anyway, we do use it in the winder, could get it hot stationary in your workshop and give it a good rev...I accidently had one running and the front pipe stated glowing red, it was unintentional...turned out to be a blocked cat...I have driven them up the road with the coupling flange loose to let the pressure out, never had any trouble personally Fred in England..
Haha, no, it rusts the crap out of everything.
Sir... could this have affected the fuel Trims making them differ from bank to bank due to the one clogged... thanks
Yes, absolutely that can happen
@@ScannerDanner so.. using VE test..and graphing the 02 and fuel trims for both banks...if the VE test fails and the 02 is rich for both banks "it's not fuel pressure or the MAF sensor" now fuel trims Will point you to the clogged bank ...😎
Hello Scanner,
I purchased your E Book recently. I like it a lot, as it is an easy read.
Question, do you have any suggestion for reducing noise using the PICO orange handle COP probe? I get a lot of noise on the screen. Any ideas?
Do you think the new PICO scope is worth the upgrade?
Thanks for what you do!
Lower your sample rate, add a filter (something the newer pico does very well)
Paul,I have a question regarding your preliminary conclusion that directed you towards a plugged exhaust : you look at the O2s on each bank at WOT and see they are rich,thus eliminating the dirty MAF possibility. My confusion comes because I thought at WOT the fuel trims go in OPEN loop and the computer is not using O2 readings. Do you record those 800mV readings right before it goes in OPEN loop?
Thanks!
Great question. Yes the system goes into open loop but the O2 sensors still produce a signal regardless of whether or not the computer is using them
are plugged exhaust systems that common? also how would you reccomend testing for this if you dont have a scope and the exhaust is super rusted?
phil holbrook check out my other videos on restricted exhaust testing. I have at least 2 other ones. Thanks !
i seen the one you have on a old school impala now like the o2 sensor reading trick under wot. i always use that now for a low power complaint! what technique do you use to find a problem for a continuos blowing fuse?
Not sure what Paul uses but there is a tool called a short finder that works real neat for finding shorts. (Mine is badged Lisle but there are a bunch of "brands")
www.amazon.com/Tool-Aid-25100-Short-Tester/dp/B000RFLR0U
It's basically a self resetting circuit breaker and an inductive meter. (I picked up a few in different values for lower/higher loads) You connect the breaker in place of the fuse. It will trip/reset cycle. Then you run the meter along the harness. As you follow the wires the meter will oscillate in time with the breaker. When you get to or pass the short the meter will stop.
I believe power probe makes one that uses RF to trace the circuit as well.
thanks Paul Danner
Hmm, very interesting! Out of curiosity, are the compression stroke numbers normal for a running engine? I was seeing 60-75 PSI at peak compression on your scope there, which is about half of what I would expect to see doing a cranking compression test. Having never analyzed a running engine before, I'm curious if this is a normal number, or if it's another sign of a restricted exhaust (can't exhale, can't inhale).
Running compression numbers (idle and no load higher rpm) will always be lower than cranking (significantly lower). This is due in part from the almost fully closed throttle plate (high manifold vacuum) and the shortened time of intake valve opening (compared to cranking rpm)
ScannerDanner
Awesome! Thank you very much! :-)
great video.thanks sir
What scan tool are you using ? Sure don't look like your verus or am I wrong
02lowrider62 I'm using my verus, just transfered the file to my laptop with shopstream connect. (Free Snap-on program)
Good way for testing for a plugged cat
Thank you i will look into it
CAN I USE PICO PRESSURE TRANSDUSER ON SNAP ON SCOPE?
+Piotr K with the correct BNC to standard banana plug adapter, yes
You will have to manually convert PSI cause the stinking S.O. don't have settings to it for you
Piotr K
ScannerDanner, my PRO virtual teacher, i really apreashiate all your great clips.
i have a humble request: if you can do a video clip about the Accelerator Pedal Position Sensor.
i realy have a tough time with it.
thanks allot and god bless.
Adi from israel.
I have some info about this on my premium channel but I'll try to do something on this channel in the future.
Thanks brother.
Thanks.
Disconnect the exhaust bit by bit until you find the culprit. 4 faulty cats on an old vehicle can write it off
How many cats do US cars have ? Does it get better when they put in a dozend cats ? How about designing engines that have cleaner raw exhaust ?
EXCELLENT
U are great thank you
Nevermind.......I HAVE to learn to read all the comments before I post my own. I just saw the note that said the car was wrecked and the "after" vid would not be available. Bummer.
If the CAT is doing its job, shouldn`t be a difference between the 2 readings of the O2 sensors? The upstream one should bounce, but the downstream one shouldn`t be close to a constant reading? So if the CAT is plugged, than the reading should be the same, because the CAT is not doing it`s job.
This test you can do same. any vehicle.sorry for my bad English
jose luis Zapote yes!
checking backpressure test on the dpfe line can bite you later because it's not 100% accurate.
I've never had an issue with it. Just have to know to disconnect vacuum line on EGR to prevent the valve from opening and affecting your measurement. Is there something else I am not considering or missing? Thanks!.
muy bueno en español por favor un abrazo
Great
Nice analysis but you don't really need to go to those lengths to diagnose a plugged exhaust.
He is excellent at showing or explaining several ways to diagnose an issue. Don't forget this is a classroom setting
I would just replace them all because it would bug me if I did not .
nevermind you answered the questions
So what you telling us is to not buy a ford lol..
Hey danner don't know if u showed this in part two but a vacuum gauge hooked to the intake could point to a plugged converter the reading on the gauge would be less vacuum at 2500 to 3000 rpm than at idle due to it not being able to breath
the intake manifold vac can be read via the running compression also .......