Less than 5 minutes in and quickly subbed. The logical approach and respect shown to the previous shop's unsuccessful repair won me over. This gentleman is exactly the kind of tech our industry needs and I want to emulate. This is going to be good. Thank you for taking the time and effort to share your knowledge.
Loved the video. I'm a new tech and I feel pretty stupid when I'm trying to diagnose engine performance issues and electrical problems. Videos like this help clarify cause and effect. Thanks for posting!
A very good , comprehensive lecture on fuel trim specifiically and over all understanding of an ecu operated vehicle, i am not a machanic but just a engines functioning enthusiastic. You are really doing a great job to spread the modren car knowledge. I reallu salute you. Kashif Pakistan.
Duane, sir ur agood teacher thankyou for sharing ur methods and experiece and wish all the young people who want to be a good mechanics learn from ur videos.thanku and cheeeeeeeers.
Oddly enough on the video at 2:28 the top code code shows "too LEARN at idle" not sure if that is a misspelling or indicating ecu was trying to learn the engine's characteristics after the battery had been disconnected? Great video, step by step pointing out not only the technical steps but teaching us to be patient and not jump to conclusions (don't guess or assume, measure the data). Thanks for this!
hey that first video on tracking down the leaks was great. I had smoked the engine earlier but thought maybe i used a little too much pressure since my smoker is a homemade version that uses a compressor and pickle jar with mineral oil and a old soldering iron. I was using only like 3 or 4 psi since thats what I heard commercial brands use. With just a few more psi's pressure I noted 2 leaks that didn't notice earlier. I used Marco's propane tip ....first nothing, but keep spraying it has to get to the first O2 sensor then start to correct. Be patient, keep up the propane on the suspected area. It took longer than I thought it would but all of a sudden my short term fuel bank went to negative 21 thus telling my ECU that there was a whole lot of extra fuel there now. Propane method works just give it time, I would guess carb cleaner method would too but keep spraying repeatedly in suspected areas.
Excellent case study! I notice that during a smoke test some techs tape off the intake, presumably to reduce back flow of smoke past the closed throttle butterfly. Evidently that's unnecessary?
Excellent!!! The B ES T !!!( except that the wand is a bit small in diameter, a bit wider still would present no danger,and be more effective) That sounds like a diesel.... there must be a way to muffle the engine noise,and still hear you nice and clear as now, sounding like a real teacher!! ( the questions and pauses are GREAT); maybe move the mike away from the engine,or use a short range mike; Thanks.
Great lessons. I got the fuel injection question right, that gives me some confidence. Just here to learn what STFT B1 is, and I think I have. Now to find out if STFT B1 at 3.1% and LTFT at 5.5 % at idle is healthy
Yes it is as stand alone data. If the 2 together was 10% or more it would be out of spec. However. stand alone data is not that helpful, it is watching the combined data in different conditions that really tells you the most accurate info. I am in the process of making a lesson on STFT & LTFT, stay tuned.
I like how you caught that. As I did I. That's what led me to read the comments to see if somebody else caught that. You are the first one I read that caught it. Meticulousness matters details are knowledge cause and reaction in a specific orders for properly diagnosing Is just a start... I hope the author mentions it in the video I'm only 2 minutes in and I know some guys that call themselves techs LOL from those 2 codes they would jump to a conclusion that it's going to be lean until they do the throttle body relearn. And think bank 1/2 is where they're going to cash their unearned check this Friday. I've watched many videos from this gentleman. He is thorough and has a way of explaining things in a comprehensive manner that a 35-year shop owner/seasoned diagnostician old dog as myself is able to gain knowledge from. And they say you can't teach an old dog new tricks. Improving myself But ultimately Getting my customer in and out faster properly the first time. Willing to admit I get tunnel vision As experienced as I am from time to time.
i have high long term bank 2 numbers and my right side exhaust is sooty .. does this mean i have a vacuum leak on bank 2 somewhere ,, i do have dual exhaust and the bank one run clean ..
Thank for video. Could you help me make sense of these STFT and LTFT values. I have 07 ford taurus, for bank 1 STFT stays between +/-3%, but LTFT stays constant at about -12% at Idle. Bank 2 is lean at idle with +12% total fuel trim. When I increase RPM to 2500, STFT jumps between +/-6% and LTFT stays constant at -19%. Bank 2 improves at 2500 RPM with about +6% total fuel trim. OBD says cylinder 1,2, and 6 misfire. I have tested injectors, replaced the leaking injector already. What do these trim value mean? How come bank 1 is rich and bank 2 is lean? Thank you.
I have a 89 s10 pickup with a manual transmission and I have replaced everything but the tps and map sensors. I live near Harrisburg Pa and can drive for about 15 minutes and then like a switch was flipped the engine starts to run really bad. I barely made it home today because the engine was really shaking. If it runs great for 15 minutes. Why does it start to run like crap? Just how do you understand this crap with fuel trim. Why can't you just send something to the ecm to force it to run the engine right. The way stuff is designed today bet you have at least $100,000 in tools just to repair this junk. Hell some manifolds are made out of plastic. is there a way to reprogram the cal pack and tell it all the sensor are new. RUN RUN RUN. I have a snap on red brick so I know what the values are.
why would my MAF be 35 g/s .it's been replaced twice.it's perfect at idel but at 2500-3000 RPM it's way up there. the P0171 that is unsolvable. after replacing the wideband sensor. short term trim it's around 10 but long term stays way over 25-35%. no air leaks showing after several smoke tests.
Great question. The LTFT is not lying. Trying to fix this from a distance would be a waste of time. Take it to a good diagnostic shop and they should be able to zero in on the real problem.
please answer me >>>>>>is the vacuum leak affect the idle only?? and why we dint start with dirty throttle gate as it should be fully close and if any dirty keep it not fully close in idle so it may lead to lean on idle
At the 7:15 mark you ruled out the MAF based on saying "it would have affected any range above idle, not just idle". But wouldn't that depend on what type of MAF problem one is dealing with? For instance; if the MAF is faulty then yes, one would agree with your conclusion, but what if it's just dirty? Then isn't it true that its ability to accurately read how much air is flowing past it is going to be more affected at idle than at higher flow rates (open throttle) ? This is because as the air flow increases it's better able to overcome the damping affect that the dirt on the hot wire is having. Thus less disparity b/w detected air flow and actual air flow at the high flow (open throttle) vs. idle (closed throttle) situation.
I have a question. I'm guessing I could get the same result if I used a water bottle sprayer. I know it's ghetto but Is there any danger to the vehicle to using that method? Anyone can answer if they know.
Hey Duane. I have an 04 Camry V6 and the LTFT is around +14% at idle on both banks. The vehicle has P0442 and P0456 small evap leak codes. Could a faulty purge valve cause the vehicle to run lean and dump more fuel?
Yes it could. +14 is quite a bit. A trick to confirm could be this, bypass the valve, clear the codes, drive for a day or two and monitor the LTFT. If it corrects then the valve is leaking, if not something else is the cause. Driving with the valve bypassed will likely set an EVAP code, due to bypass, but you are concerned about LTFT.
Thanks Duane! I actually swapped out the purge valve with another one and it has the same readings. I did use a cheap one from online but it seems like there’s something else going on. The car has 200k miles. Do you think a smoke test would be the next step? And also, what should the MAF sensor reading be?
So i have an issue where i will give it a lot of gas and the car will then throw a p300 code and misfire and hesitate if i accelerate, and it wont be until i turn the ignition off and on again until it stops misfiring. Eventually my car will get a p0170 code which is a fuel trim code for bank 1. When i plug my OBD in and read the real time data the only thing abnormal is the long term fuel trim in bank 1 which is exceptionally high at around +30; so i understand that bank 1 is running lean. What I dont understand is why the short term fuel trim for bank 1 is normal (within positive or negative 3) but the long term fuel trim isnt. So i read that a vacuum leak is the cheapest thing to solve so I got some new rubber vacuum line and replaced nearly all the hoses, most were cracked on my 22 year old car. That didnt solve the issue. The fact that its strictly in bank 1 tells me the MAF is fine and that it isnt a fuel issue because both banks would be affected. What further confuses me is the fact that it only throws these codes when I accelerate fast and the automatic transmission downshifts. I have tried revving the engine on neutral and seeing if the issue occurs and it does not which tells me it happens under load. To top it off, a p410 code will go off indicating the secondary air injector is malfunctioning however i have tested it and the pump is fine it fires right up when i jump it to my battery. Im at a total loss as to what to check next. PLZ HELP!
I can understand your confusion. You are dancing around the problem instead of focusing on the specific issue. P0300 random misfire is the issue, everything else is probably a symptom caused by the misfire. Focus on what is causing the random misfire. Clue; since it is random it is probably air/fuel mixture related rather than spark related.
@@strokewarrior5762 thanks for the prompt reply, im thinking of checking the fuel injectors on that bank side. Also can it possibly be an O2 sensor on that bank?
@@watchdogu.s.a.8973 Hello there thank you for the reply, unfortunately I have not figured it out, I have put it off for the past few months because of school but so far 2 auto shops have not been able to help me and are also not sure what the cause is. So far I have checked and ensured fuel rail is getting adequate fuel pressure, injectors are working and firing appropriately, the exhausts are not clogged or restricted, there are no vacuum leaks whatsoever (I just rebuilt the air intake mechanism and sealed everything); i put in new spark plugs, valve cover gaskets, checked the coils and wires and everything is fine in that regard. I was going to have mercedes dealership diagnose it for like $150 and then I was going to fix it myself. The only error code i still have is the p0300 random cylinder misfire and the p0170 fuel trim bank 1 error. The long term fuel trim in bank 1 is 30 but the short term fuel trim is normal and the fuel trims in bank 2 are also normal. I swapped around some O2 sensors to see if the problem would jump to the other bank but it didnt so I dont think its an O2 sensor.
@@MoeHawk94 Have you checked your air intake to be sure you're not drawing in air that isn't flowing through the mass airflow sensor? A crack or hole in the duct or a loose cover on the filter box or a hole in the filter box could all allow un-metered air into the engine and create the lean condition. A leak around an intake plenum maybe. There are several ways to find such a leak including a smoke test. Just some thoughts...
@@realfixesrealfast thanks because this is something I'm really trying to grasp... i have a cheap lil obd scan so i have to rely on digital results rather than the graph from Good scanners.. on my 750i before i cleaned my o2 sensors i was negative 7-8 for both banks and all 4 sensors.. after cleaning the upstream sensors i noticed a change in my scanner and it was 0.0 and flux up to 3+ but stayed within that realm while i was still getting negative 7 8 for the downstream sensors.... im hoping the clean will have the same effect.. all 4 sensors were Heavily corroded with grime.. some 400 grit sand paper and i cleaned them all great...
hello. SHRTFT1(%) = +6.3 and LONGFT1(%) = -7.0 , is good or bad? Another question: SHRTFTB1S1(%) = 2.3 and SHRTFTB1S2(%) = -100.0, is good or bad? what does "G"?
@@realfixesrealfast seems weird. O2S B1 S2 is fluctuating correctly, but O2S B2 S2 sits at about .685V steady flatline, when I bring the RPM up it drops briefly but then goes back up and sits there. At the same time I got a 10.9% LTFT Bank 2. Bank 1 goes into closed loop but Bank 2 stays open. I've got a below threshold on Bank 1 but both cats are running at about the same temperatures. I've got a P0300, P0301 and P0305.
Sir may i know if a car is in normal operation no check engine light what was the signal look like at short term fuel trim and the signal looks like at long term fuel trim tnx sir
I know you have the engine running when testing with propane so the engine vacuum pulls the propane in. Do you run the engine when using the smoke machine? I couldn't tell if the engine vacuum was pulling the smoke in or if the machine pumped it in? Great video as always, I really like the interactive diagnosis
My car has high positive ltft of around 15% at idle 20% at 2500 rpm 0% at 3000 rpm or more My car doesnt have maf sensor but does have map sensor Is vacuum leak is the cause or should i look for fuel deleviry problem? Pls reply
yes you need to look at fuel delivery as a possible cause. And you need to watch ltft at a sustained rpm, not a snap rpm. Since your ltft is positive, the pcm is adding fuel. Try adding external fuel yourself with propane and see if it corrects.
My Stroke My Recovery , i would like to stress that the mentioned above ltft values are at sustained rpm not snap one, so as you've mentioned it is a fuel delivery problem, i've replaced the fuel filter , cleaned my fuel injectors, checked the fuel pressure regulator , is my fuel pump weak? You said to add propane? How is that done? Thanks
My Stroke My Recovery, why is the values of ltft decrease at 3000 rpm ? Pls explain that in case of fuel delivery problem? Note: car has returnless fuel system
Think about this, If your pcm is adding fuel to correct for low fuel pressure OR volume, then you can simulate that yourself by externally adding your own fuel (propane). Heres how. Have your scanner showing the stft & ltft data, then simply open the cover to your air filter, use a hand held propane bottle with a nozzle, and let propane flow into your intake mixed with the normal air. Kinda like your creating an air leak but instead it's extra fuel. The pcm should see that extra fuel and not need to add fuel itself. Watch our scanner data for an adjustment. If by you adding fuel the pcm does NOT need to, you've identified the issue and now need to find the reason your pcm needs add fuel. Quite often that is due to low fuel pressure/volume.
realfixesrealfast, hello sir .. I really apreciate your response and help with my problem, i did the propane test as you instructed and the ltft value dropped signifitly to about 2% & stft values became more negative , i think that means there is fuel delivery problem ! Not much fuel introduced to the engine at idle! But at higher rpm's above 3000 fuel is being introduced as it should! So whats the problem now ? I changed the fuel filter , cleaned my fuel injectors, replaced the fuel pump electric motor ( only motor) Inspected fuel pressure regulator , but still the same results Pls advice Thanks
Bad advice. The check engine lightcCame on within 5 miles of leaving the shop. That means the shop just turned off the codes with their scanner. Had theyy test driven it awhile they would have gotten the check engine light. Dirtbags.
My first assumption is a lot of mechanics don't give a crap about ripping people off. ;-) (Partially joking. There's good mechanics out there but I don't like people. To find the good ones you have to get to know them. I don't trust random people.) I can't wait until I get a hoist and tire machines to eliminate anyone other than me touching my vehicles.
Caddy Guy Gaming haha! It is very easy to talk! You think becoming a good tech is just tools or a hoist? You need years of experience! You complain or think they didn't try to fix the car before, they just couldn't because of the lack of experience! One thing I say to my costumers is that if car is not fix don't pay for parts or labor. He "the costumer" should go back to the shop that work on his car and get his money back or let them fix it, especially if light comes back after 5 miles of driving. Obviously whatever they did was not the fix. Truly something as simple as lean condition affecting both banks and showing that is at idle screams vacumm leak. So again who ever worked on that car did not have much experience.
Did I say It was only tools and hoist? I've been doing pretty good so far doing my own work for the past 15 years. I think ill stay on that route. My problem with taking it back to someone that didn't fix something, or messed something up is, if they messed up the first time, why would I let them touch it again? It's really a moot point though, because nobody touches my stuff, with exception to tires. I need a hoist so I can pull the engine from my 02 Deville to fix the crankcase seal. As well as countless other projects. For me, once trust is broken, it is very difficult, if not impossible to get back. Why are you getting your panties in such a bunch anyway? Do you have no sense of humor? Also, where do you get the theory I complain? Hard to complain when I don't let anyone work on my vehicles.
HE GOT A THUMBS DOWN SO FAST BECAUSE ANY IDIOT CAN WATCH THIS VIDEO THIS MAN MADE TO HELP PEOPLE UNDERSTAND LTFT ( LONG TERM FUEL TRIM ) AND FIND THE SLIGHTEST SLIP UP AND MAKE A RUDE OR BAD COMMENT ON IT OR GIVE HIM A THUMBS DOWN OR BOTH..TO THE PERSON WHO DID THIS DON'T BE A A**hOLE ABOUT IT..IF YOU THINK IT'S SO EASY TO MAKE A VIDEO TO TRY AND HELP PEOPLE WHO DO NOT UNDERSTAND OR FULLY UNDERSTAND LTFT AND STFT MAKE A VIDEO YOURSELF AND THE FIRST MISTAKE OR SIP SO TO SPEAK SEE HOW YOU ENJOY A RUDE COMMENT OR THUMBS DOWN..THIS MAN KNEW WHAT HE WAS TALKING ABOUT AND WAS SHARING HS KNOWLEDGE WITH OTHERS...WE SHOULD THANK HIM NOT MAKE RUDE OR STUPID COMMENTS.PLUS YES A VACUUM LEAK WILL CAUSE A LEAN CONDITION IN THE ENGINE AND THE COMPUTER DETECTS THIS VIA AIR/FUEL SENSOR AKA O2 SENSOR AND TRYS TO ADJUST BY ADDING MORE FUEL CAUSING A RICH CONDITION..THANK YOU TO EVERYONE UNDERSTANDING !
![Short Term and Long Term Fuel Trims Explained [Easily]](/img/n.gif)
Less than 5 minutes in and quickly subbed. The logical approach and respect shown to the previous shop's unsuccessful repair won me over. This gentleman is exactly the kind of tech our industry needs and I want to emulate.
This is going to be good. Thank you for taking the time and effort to share your knowledge.
Thank you Andrew, glad it was helpful. I appreciate you taking the time to comment.
Great advice from the beginning of the video and well pointed out. Thank you for the time, resources, and effort you did put into this video.
Loved the video. I'm a new tech and I feel pretty stupid when I'm trying to diagnose engine performance issues and electrical problems. Videos like this help clarify cause and effect. Thanks for posting!
A very good , comprehensive lecture on fuel trim specifiically and over all understanding of an ecu operated vehicle, i am not a machanic but just a engines functioning enthusiastic. You are really doing a great job to spread the modren car knowledge. I reallu salute you.
Kashif
Pakistan.
good teacher and a good soul.. God Bless! and thanks for the lesson : )
Great video to diagnose abnormal combustion by using graphic live data
Congratulations. Great video. You have a pretty good idea on how O2 sensor and Fuel trims work together. You have my thumbs up and bell ringing.
good video nicely done I always like it when you quickly summarize it and then go into it in more detail
An excellent video which combines both theory and real world diagnostic techniques. I like the smoke machine!
Your explanation is good. .and you have special method for transfer information ....thank you
Just Excellent Presentation! New subscriber and I'm looking forward to watching many more of your videos.....THANKS!
Great video. Thank you. I certainly learned from this. I cant wait to watch more from this channel. Happy New Year!
A terrific lesson, Thank You Very Much.
Duane, sir ur agood teacher thankyou for sharing ur methods and experiece and wish all the young people who want to be a good mechanics learn from ur videos.thanku and cheeeeeeeers.
My first instinct was smoke.. especially since it seemed like a vacuum leak.. very good info... thank you ..
Always something to learn on this channel.
Oddly enough on the video at 2:28 the top code code shows "too LEARN at idle" not sure if that is a misspelling or indicating ecu was trying to learn the engine's characteristics after the battery had been disconnected? Great video, step by step pointing out not only the technical steps but teaching us to be patient and not jump to conclusions (don't guess or assume, measure the data). Thanks for this!
hey that first video on tracking down the leaks was great. I had smoked the engine earlier but thought maybe i used a little too much pressure since my smoker is a homemade version that uses a compressor and pickle jar with mineral oil and a old soldering iron. I was using only like 3 or 4 psi since thats what I heard commercial brands use. With just a few more psi's pressure I noted 2 leaks that didn't notice earlier. I used Marco's propane tip ....first nothing, but keep spraying it has to get to the first O2 sensor then start to correct. Be patient, keep up the propane on the suspected area. It took longer than I thought it would but all of a sudden my short term fuel bank went to negative 21 thus telling my ECU that there was a whole lot of extra fuel there now. Propane method works just give it time, I would guess carb cleaner method would too but keep spraying repeatedly in suspected areas.
Thanks, I appreciate you taking the time to comment
Excellent case study! I notice that during a smoke test some techs tape off the intake, presumably to reduce back flow of smoke past the closed throttle butterfly. Evidently that's unnecessary?
Finally, somebody knows how to G-D TEACH! Thank you, Sir.
Very well done . you must have been a teacher at one time
Excellent video
Who else had a small giggle when he said. As soon as she leaves the check engine light comes back on.
Nice video
Hi thanks for your nice video.
Where can I get that wand for propane please leave the link.
Link for the tool. www.realfixesrealfast.com/propane-enrichment-tool.html
thank you
Great training video, where can I buy the tip for the Propane canister?
Excellent!!! The B ES T !!!( except that the wand is a bit small in diameter, a bit wider still would present no danger,and be more effective)
That sounds like a diesel.... there must be a way to muffle the engine noise,and still hear you nice and clear as now, sounding like a real teacher!! ( the questions and pauses are GREAT); maybe move the mike away from the engine,or use a short range mike;
Thanks.
Thanks for your comments, and tips Jose, I appreciate them. Duane
Very interesting stuff. 👍👍
Great just great. Thank you!!!!.
Very educative sir ,I watch the video severel times i subscribe d today greetings from Romania
Glad it helped, thanks for your comments.
Exselecte diagnostic amigo
Great lessons. I got the fuel injection question right, that gives me some confidence. Just here to learn what STFT B1 is, and I think I have. Now to find out if STFT B1 at 3.1% and LTFT at 5.5 % at idle is healthy
Yes it is as stand alone data. If the 2 together was 10% or more it would be out of spec. However. stand alone data is not that helpful, it is watching the combined data in different conditions that really tells you the most accurate info. I am in the process of making a lesson on STFT & LTFT, stay tuned.
@@realfixesrealfast thanks!!
excellent
I like how snap on messed up it said learn not lean lol. Good video and its great to have that kind of record available. Great job explaining
I like how you caught that. As I did I. That's what led me to read the comments to see if somebody else caught that. You are the first one I read that caught it. Meticulousness matters details are knowledge cause and reaction in a specific orders for properly diagnosing Is just a start...
I hope the author mentions it in the video I'm only 2 minutes in and I know some guys that call themselves techs LOL from those 2 codes they would jump to a conclusion that it's going to be lean until they do the throttle body relearn. And think bank 1/2 is where they're going to cash their unearned check this Friday.
I've watched many videos from this gentleman. He is thorough and has a way of explaining things in a comprehensive manner that a 35-year shop owner/seasoned diagnostician old dog as myself is able to gain knowledge from.
And they say you can't teach an old dog new tricks. Improving myself But ultimately Getting my customer in and out faster properly the first time. Willing to admit I get tunnel vision As experienced as I am from time to time.
Outstanding
i have high long term bank 2 numbers and my right side exhaust is sooty .. does this mean i have a vacuum leak on bank 2 somewhere ,, i do have dual exhaust and the bank one run clean ..
Thank for video. Could you help me make sense of these STFT and LTFT values. I have 07 ford taurus, for bank 1 STFT stays between +/-3%, but LTFT stays constant at about -12% at Idle. Bank 2 is lean at idle with +12% total fuel trim. When I increase RPM to 2500, STFT jumps between +/-6% and LTFT stays constant at -19%. Bank 2 improves at 2500 RPM with about +6% total fuel trim. OBD says cylinder 1,2, and 6 misfire. I have tested injectors, replaced the leaking injector already. What do these trim value mean? How come bank 1 is rich and bank 2 is lean? Thank you.
I thought the throttle body needed cleaning, but I naturally would smoke it
I know his grandsons will be very knowledgeable about this
good stuff
Thanks for the video. I got to get me one of those propane tips.
Matt Trotta , hi Matt did you ever find the tip? I'm looking for one as well.
very nice
I have a 89 s10 pickup with a manual transmission and I have replaced everything but the tps and map sensors. I live near Harrisburg Pa and can drive for about 15 minutes and then like a switch was flipped the engine starts to run really bad. I barely made it home today because the engine was really shaking. If it runs great for 15 minutes. Why does it start to run like crap? Just how do you understand this crap with fuel trim. Why can't you just send something to the ecm to force it to run the engine right. The way stuff is designed today bet you have at least $100,000 in tools just to repair this junk. Hell some manifolds are made out of plastic. is there a way to reprogram the cal pack and tell it all the sensor are new. RUN RUN RUN. I have a snap on red brick so I know what the values are.
why would my MAF be 35 g/s .it's been replaced twice.it's perfect at idel but at 2500-3000 RPM it's way up there. the P0171 that is unsolvable. after replacing the wideband sensor. short term trim it's around 10 but long term stays way over 25-35%. no air leaks showing after several smoke tests.
Great question. The LTFT is not lying. Trying to fix this from a distance would be a waste of time. Take it to a good diagnostic shop and they should be able to zero in on the real problem.
@@realfixesrealfast that's just the problem, finding an honest, good diagnostic shop that knows what they're doing instead of throwing parts at it.
please answer me >>>>>>is the vacuum leak affect the idle only?? and why we dint start with dirty throttle gate as it should be fully close and if any dirty keep it not fully close in idle so it may lead to lean on idle
Probably be better off just swapping the technique of smoke and propane....smoke first THEN propane. This is a fantastic video btw.
At the 7:15 mark you ruled out the MAF based on saying "it would have affected any range above idle, not just idle". But wouldn't that depend on what type of MAF problem one is dealing with? For instance; if the MAF is faulty then yes, one would agree with your conclusion, but what if it's just dirty? Then isn't it true that its ability to accurately read how much air is flowing past it is going to be more affected at idle than at higher flow rates (open throttle) ? This is because as the air flow increases it's better able to overcome the damping affect that the dirt on the hot wire is having. Thus less disparity b/w detected air flow and actual air flow at the high flow (open throttle) vs. idle (closed throttle) situation.
I have a question. I'm guessing I could get the same result if I used a water bottle sprayer. I know it's ghetto but Is there any danger to the vehicle to using that method? Anyone can answer if they know.
Hey Duane. I have an 04 Camry V6 and the LTFT is around +14% at idle on both banks. The vehicle has P0442 and P0456 small evap leak codes. Could a faulty purge valve cause the vehicle to run lean and dump more fuel?
Yes it could. +14 is quite a bit. A trick to confirm could be this, bypass the valve, clear the codes, drive for a day or two and monitor the LTFT. If it corrects then the valve is leaking, if not something else is the cause. Driving with the valve bypassed will likely set an EVAP code, due to bypass, but you are concerned about LTFT.
Thanks Duane! I actually swapped out the purge valve with another one and it has the same readings. I did use a cheap one from online but it seems like there’s something else going on. The car has 200k miles. Do you think a smoke test would be the next step? And also, what should the MAF sensor reading be?
So i have an issue where i will give it a lot of gas and the car will then throw a p300 code and misfire and hesitate if i accelerate, and it wont be until i turn the ignition off and on again until it stops misfiring. Eventually my car will get a p0170 code which is a fuel trim code for bank 1. When i plug my OBD in and read the real time data the only thing abnormal is the long term fuel trim in bank 1 which is exceptionally high at around +30; so i understand that bank 1 is running lean.
What I dont understand is why the short term fuel trim for bank 1 is normal (within positive or negative 3) but the long term fuel trim isnt. So i read that a vacuum leak is the cheapest thing to solve so I got some new rubber vacuum line and replaced nearly all the hoses, most were cracked on my 22 year old car. That didnt solve the issue.
The fact that its strictly in bank 1 tells me the MAF is fine and that it isnt a fuel issue because both banks would be affected. What further confuses me is the fact that it only throws these codes when I accelerate fast and the automatic transmission downshifts. I have tried revving the engine on neutral and seeing if the issue occurs and it does not which tells me it happens under load. To top it off, a p410 code will go off indicating the secondary air injector is malfunctioning however i have tested it and the pump is fine it fires right up when i jump it to my battery. Im at a total loss as to what to check next. PLZ HELP!
I can understand your confusion. You are dancing around the problem instead of focusing on the specific issue. P0300 random misfire is the issue, everything else is probably a symptom caused by the misfire. Focus on what is causing the random misfire. Clue; since it is random it is probably air/fuel mixture related rather than spark related.
@@strokewarrior5762 thanks for the prompt reply, im thinking of checking the fuel injectors on that bank side. Also can it possibly be an O2 sensor on that bank?
Hello. I'm just wondering if you found the cause of your problem? I'm watching many videos and reading comments to help learn diagnostics.
@@watchdogu.s.a.8973 Hello there thank you for the reply, unfortunately I have not figured it out, I have put it off for the past few months because of school but so far 2 auto shops have not been able to help me and are also not sure what the cause is. So far I have checked and ensured fuel rail is getting adequate fuel pressure, injectors are working and firing appropriately, the exhausts are not clogged or restricted, there are no vacuum leaks whatsoever (I just rebuilt the air intake mechanism and sealed everything); i put in new spark plugs, valve cover gaskets, checked the coils and wires and everything is fine in that regard. I was going to have mercedes dealership diagnose it for like $150 and then I was going to fix it myself. The only error code i still have is the p0300 random cylinder misfire and the p0170 fuel trim bank 1 error. The long term fuel trim in bank 1 is 30 but the short term fuel trim is normal and the fuel trims in bank 2 are also normal. I swapped around some O2 sensors to see if the problem would jump to the other bank but it didnt so I dont think its an O2 sensor.
@@MoeHawk94 Have you checked your air intake to be sure you're not drawing in air that isn't flowing through the mass airflow sensor? A crack or hole in the duct or a loose cover on the filter box or a hole in the filter box could all allow un-metered air into the engine and create the lean condition.
A leak around an intake plenum maybe. There are several ways to find such a leak including a smoke test.
Just some thoughts...
where should the short and long term trims be stationed for correct functionality...
as a rule of thumb when you combine soft bank 1 with long term bank 1 they should be 10% or less
@@realfixesrealfast thanks because this is something I'm really trying to grasp... i have a cheap lil obd scan so i have to rely on digital results rather than the graph from Good scanners.. on my 750i before i cleaned my o2 sensors i was negative 7-8 for both banks and all 4 sensors.. after cleaning the upstream sensors i noticed a change in my scanner and it was 0.0 and flux up to 3+ but stayed within that realm while i was still getting negative 7 8 for the downstream sensors.... im hoping the clean will have the same effect.. all 4 sensors were Heavily corroded with grime.. some 400 grit sand paper and i cleaned them all great...
hello. SHRTFT1(%) = +6.3 and LONGFT1(%) = -7.0 , is good or bad?
Another question: SHRTFTB1S1(%) = 2.3 and SHRTFTB1S2(%) = -100.0, is good or bad?
what does "G"?
Hello i got the short term fuel -10 and more and the long term fuel 0.8 and i have engine and rpm shaking can you help please
I have a 06 Jeep grand Cherokee. 3.7 engine. trans over temp light on. what is that? fluid is up to mark at idle.
Spray that spot with carb cleaner.
Okay, .700 v os2 bank2 and 10% LTtrim bank 2, misfire on 1 and 5.
Any thoughts??
not enough info to do anything with that. Its not specific data, it's what the data is doing.
@@realfixesrealfast seems weird. O2S B1 S2 is fluctuating correctly, but O2S B2 S2 sits at about .685V steady flatline, when I bring the RPM up it drops briefly but then goes back up and sits there.
At the same time I got a 10.9% LTFT Bank 2. Bank 1 goes into closed loop but Bank 2 stays open.
I've got a below threshold on Bank 1 but both cats are running at about the same temperatures.
I've got a P0300, P0301 and P0305.
Sir may i know if a car is in normal operation no check engine light what was the signal look like at short term fuel trim and the signal looks like at long term fuel trim tnx sir
At normal conditions both the STFT & LTFT values should fluctuate and be less than 10%
I know you have the engine running when testing with propane so the engine vacuum pulls the propane in. Do you run the engine when using the smoke machine? I couldn't tell if the engine vacuum was pulling the smoke in or if the machine pumped it in?
Great video as always, I really like the interactive diagnosis
Good question. No, you do not run the engine for the smoke test. If you did, the engine would just pump the smoke out the tail pipe.
Love ur video. HD video would be better
My car has high positive ltft of around 15% at idle
20% at 2500 rpm
0% at 3000 rpm or more
My car doesnt have maf sensor but does have map sensor
Is vacuum leak is the cause or should i look for fuel deleviry problem?
Pls reply
yes you need to look at fuel delivery as a possible cause. And you need to watch ltft at a sustained rpm, not a snap rpm. Since your ltft is positive, the pcm is adding fuel. Try adding external fuel yourself with propane and see if it corrects.
My Stroke My Recovery , i would like to stress that the mentioned above ltft values are at sustained rpm not snap one, so as you've mentioned it is a fuel delivery problem, i've replaced the fuel filter , cleaned my fuel injectors, checked the fuel pressure regulator , is my fuel pump weak? You said to add propane? How is that done?
Thanks
My Stroke My Recovery, why is the values of ltft decrease at 3000 rpm ? Pls explain that in case of fuel delivery problem?
Note: car has returnless fuel system
Think about this, If your pcm is adding fuel to correct for low fuel pressure OR volume, then you can simulate that yourself by externally adding your own fuel (propane). Heres how. Have your scanner showing the stft & ltft data, then simply open the cover to your air filter, use a hand held propane bottle with a nozzle, and let propane flow into your intake mixed with the normal air. Kinda like your creating an air leak but instead it's extra fuel. The pcm should see that extra fuel and not need to add fuel itself. Watch our scanner data for an adjustment. If by you adding fuel the pcm does NOT need to, you've identified the issue and now need to find the reason your pcm needs add fuel. Quite often that is due to low fuel pressure/volume.
realfixesrealfast, hello sir ..
I really apreciate your response and help with my problem, i did the propane test as you instructed and the ltft value dropped signifitly to about 2% & stft values became more negative , i think that means there is fuel delivery problem ! Not much fuel introduced to the engine at idle! But at higher rpm's above 3000 fuel is being introduced as it should!
So whats the problem now ?
I changed the fuel filter , cleaned my fuel injectors, replaced the fuel pump electric motor ( only motor)
Inspected fuel pressure regulator , but still the same results
Pls advice
Thanks
Lab scope I don't think you were using the scope you were using the data graph
CAN U GET A BETTER MIC? I LIKE UR VIDEOS BUT MY NEWBORN >DOESN'T!
Bad advice. The check engine lightcCame on within 5 miles of leaving the shop. That means the shop just turned off the codes with their scanner. Had theyy test driven it awhile they would have gotten the check engine light. Dirtbags.
My first assumption is a lot of mechanics don't give a crap about ripping people off. ;-) (Partially joking. There's good mechanics out there but I don't like people. To find the good ones you have to get to know them. I don't trust random people.)
I can't wait until I get a hoist and tire machines to eliminate anyone other than me touching my vehicles.
Caddy Guy Gaming haha! It is very easy to talk! You think becoming a good tech is just tools or a hoist? You need years of experience! You complain or think they didn't try to fix the car before, they just couldn't because of the lack of experience! One thing I say to my costumers is that if car is not fix don't pay for parts or labor. He "the costumer" should go back to the shop that work on his car and get his money back or let them fix it, especially if light comes back after 5 miles of driving. Obviously whatever they did was not the fix. Truly something as simple as lean condition affecting both banks and showing that is at idle screams vacumm leak. So again who ever worked on that car did not have much experience.
Did I say It was only tools and hoist? I've been doing pretty good so far doing my own work for the past 15 years. I think ill stay on that route. My problem with taking it back to someone that didn't fix something, or messed something up is, if they messed up the first time, why would I let them touch it again? It's really a moot point though, because nobody touches my stuff, with exception to tires. I need a hoist so I can pull the engine from my 02 Deville to fix the crankcase seal. As well as countless other projects. For me, once trust is broken, it is very difficult, if not impossible to get back.
Why are you getting your panties in such a bunch anyway? Do you have no sense of humor?
Also, where do you get the theory I complain? Hard to complain when I don't let anyone work on my vehicles.
if your so good why are u watching a instruction video of how to repair a vehicle?
Air leak!!😁
purge valve
Already a thumbs down! I wish they would say why!!
roadkill5333 he said he had a vacuum leak.
HE GOT A THUMBS DOWN SO FAST BECAUSE ANY IDIOT CAN WATCH THIS VIDEO THIS MAN MADE TO HELP PEOPLE UNDERSTAND LTFT ( LONG TERM FUEL TRIM ) AND FIND THE SLIGHTEST SLIP UP AND MAKE A RUDE OR BAD COMMENT ON IT OR GIVE HIM A THUMBS DOWN OR BOTH..TO THE PERSON WHO DID THIS DON'T BE A A**hOLE ABOUT IT..IF YOU THINK IT'S SO EASY TO MAKE A VIDEO TO TRY AND HELP PEOPLE WHO DO NOT UNDERSTAND OR FULLY UNDERSTAND LTFT AND STFT MAKE A VIDEO YOURSELF AND THE FIRST MISTAKE OR SIP SO TO SPEAK SEE HOW YOU ENJOY A RUDE COMMENT OR THUMBS DOWN..THIS MAN KNEW WHAT HE WAS TALKING ABOUT AND WAS SHARING HS KNOWLEDGE WITH OTHERS...WE SHOULD THANK HIM NOT MAKE RUDE OR STUPID COMMENTS.PLUS YES A VACUUM LEAK WILL CAUSE A LEAN CONDITION IN THE ENGINE AND THE COMPUTER DETECTS THIS VIA AIR/FUEL SENSOR AKA O2 SENSOR AND TRYS TO ADJUST BY ADDING MORE FUEL CAUSING A RICH CONDITION..THANK YOU TO EVERYONE UNDERSTANDING !
Dirty throttle body ?
You are an awesome instructor hands down!