Fuel Trims - Where to Begin your Diagnosis For Rich or Lean (p0171, P0172, P0174, P0175)
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- Опубликовано: 16 июл 2024
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Your check engine light just came on, your car is running poorly, you’ve just hooked up a scan tool and got codes such as P0171 and P0174. Or your car just started and stalled with no check engine light! What do you do? Join us as we get in depth into fuel trims and how to use all of that information to your advantage when diagnosing for rich or lean concerns. We explore where fuel trims come from, the air/fuel ratio, and what happens when things aren’t working quite right. Don’t miss out on this introduction into fuel trims!
As always if you like what you see be sure to give us the “thumbs up” and please subscribe. Head on over to our website if you’d like an email reminder every time we have a new class! www.wellsve.com 
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P0171 basically means you have a vacuum leak usually the first place I go to the gas cap to make sure it was tightened properly because if it is not then you're going to show a vacuum leak.
Hey David, thanks for watching. So a vacuum leak can set a P0171 but there's also a ton of other things. Also, the gas cap is more likely to set an EVAP code like P0440 or something before setting a lean code.
Mike Becker, Senior Instructor
Gracias maestro. Veo sus videos en español pero en inglés un poco. Gracias nuevamente por su aporte a la enseñanza
Taken on a 175km trip now all looks good (touch wood) STFT around -1.6 Banks 1 and 2
LTFT around -7 Banks 1 and 2 and motor seems to be running smoother. Next I will check Fuel consumption Thanks for your help. Over here in Australia most of the mechanics I have spoken to about this problem just tell me to just reset the codes, this has made my head hurt for o many years, my fingers are crossed.
Graeme in OZ
My fingers are crossed for you too, Graeme Redman!
Mike Becker, Senior Technical Instructor
Blackbox is ecu. New stuff to learn for old timer.I ask my kids if I have trouble with my pc. Lol. I wondered how my bike starts without choke, now I know.I have to watch more of your vids. Great stuff.
Hey Denis! I'm glad you're catching on and educating yourself! Any questions, don't hesitate.
Mike Becker, Senior Technical Instructor
South Main Auto sent me to see your class, Great program, I need lots of this and will follow more videos.
Awesome John! Thanks!
Mike Becker, Senior Technical Instructor
Thank you so much for taking the time to explain everything!!
Hey J G, thanks for taking the time to watch and comment!
Mike Becker, Senior Technical Instructor
hi from vegas really love the way you explain things on the fuel trim made me look at diag from a whole different view thanks
Thanks for detailed explanations. I appreciate all work you put into making this video.
Hey PistonShack, thanks for watching! :)
Mike Becker, Senior Instructor
My 2001 vw beetle glx 1.8t..had PO172..
Cleaned the airflow sensor and throttle body..Runs like brand new now..As a mechanic for 32 years in Audi Bmw Mercedes I recommend cleaning the airflow sensor every oil change..at 2000 miles..Thank You and I approve this message...
Thanks for sharing
This dude really knows what he's doing!
Great presentation Mike and looking forward to your lecture on the wide band sensors. Have a good weekend!
Thanks Stuzman! Glad you liked it, see you on the next one!
Mike Becker, Technical Services Instructor
Very informed video, a lot of doubts have been cleared. Your explanation are terrific.
Thanks for watching Mukesh!
Mike Becker, Senior Instructor
Mike- we just had a uplander in class with rich codes and intermittent hard start. FFV, alcohol content was reading 75% but actual content in fuel was less then 10%!
That's crazy, nice find Jake!!!!! Chevy seems to have an issue with this. Was this a sensor style or algorithim style alcohol content monitor? Actually in the next class we are going to be talking about measuring that content as part of the diag procedure.
Mike Becker, Technical Services Instructor
you are a very good teacher the best on the internet by far the way you explaine things im going to start to watch a lot of your content excellent
Hey Wackey, thanks for watching! I really appreciate the kind words.
~Mike
thank you for this video , excellent information . I've been wrenching since the 80's and I still love to learn about how cars work and this is a fascinating time to be a tech with all the changes happening year to year . I also didn't see the need for parts to be shown .
Hey John, thanks! It really is an amazing time to be in the automotive industry. So much to learn, it's evolving soooo quickly!
Mike Becker, Senior Technical Services Instructor
Oh my, a God sent gem thank you guys.
Thanks for watching Emmanuel!
Mike Becker, Senior Technical Instructor
A little late to the game Mike, but THANK YOU! for the invaluable content. These classes are pure gold when it comes to understanding how these systems work. This is one of those principle concepts that if you can understand you can troubleshoot a lot of issues that we face as techs. I found your channel from Eric over at SMA and I'm sure glad I did. Cheers from Stevens Point.
Hey Jordan,
Your welcome from GoTech and thanks for your support!
You are 100% correct! understanding principles and concepts is the key to diagnostics.
Keep up the good work!
~Ryan Wilsing
Absolutely Brilliant!!! Thanks for the Detailed Explanation!
Great channel to keep learning. Thank you very much guys.
Hey, thank you very much for watching and commenting!
Mike Becker, Senior Instructor
Wisconsin!!!! ...and thank you for actually being well educated. So much bad info out there. ...people who think that O2 sensors measure fuel and not oxygen. The moment you said that a rich mixture could cause a misfire, which would actually create a lean reading from the O2 sensor, I knew that you actually knew what you were talking about.
Hey T D, thanks! You a Wisconsinite as well?
Mike Becker, Senior Instructor
@@GoTechTraining yes! Milwaukee
@@GoTechTraining actually was kinda losing my mind about an O2 sensor on my 1999 Saturn SL2. Had a head gasket go recently because back when I rebuilt the engine, I used bad head bolt instruction from a Haynes manual. Managed to get 140,000 miles out of the gasket using original head bolts, but it finally failed, and kinda contaminated the O2 sensor. New bolts, new gasket, proper tightening sequence, new fuel filter at 358,000 miles (3rd one for this car), and new O2 sensor, and whenever I took the car over 70 or floored it, the readings would max and then drop to zero. Thought too much fuel or too little fuel, but the pressure holds constant on the original pump, and trims are otherwise in range. Put back in the old sensor, and it started doing the same thing. At this point I'm thinking wiring or computer, and the old one did it worse at any freeway speeds. It was terrible. Made the car run super rich because the computer started adding fuel when it dropped to zero. (Also checked plug gaps, wire resistance, and coil resistance at 70°F.) Finally grabbed an old sensor I had lying around that I pulled long ago for slow response, and it works at all speeds and loads! So they were just overheating and shorting. Have another on order. Hope it won't be defective.
Okay after watching the this video training my question was answered! Great training thanks!
Such a great teacher...god bless you
Also for the vehicle to be running rich, you could be getting blow by and the air gathering up oil and taking it through a failed crank case vent or pcv into the intake whereby it would be burnt and making the exhaust rich.
Hey James, you're absolutely correct. Oil could end up in the intake manifold and cause the engine to run right. Nice!
Mike Becker, Technical Services Instructor
Wonderful class...excellent information. Greatly appreciated ..... Thanks and take care
Hey Charles, thanks! Glad you liked the class!
Mike Becker, Senior Technical Instructor
Very good, thanks for explaining the details - your words make great sense
Hey Bob, thanks for watching!
Mike Becker, Senior Instructor
Better than tele. Keep up the good work. Stft and ltft no longer a mystery. Thanks.
Hey Jesse! Thanks, best part is that it's free unlike cable :) Thanks for watching!
Mike Becker, Technical Services Instructor
Very good video with a lot of helpful information . Thank you. Quick question, My car recently was running lean 21 percent lean long trim and 18 short trim on bank 2 due to a exhaust leak between the 2 flanges right before the cat. I got that fixed and now the car sometimes runs -18 but mostly stays on -6 to -12 range on short trim and bounces from -10 to 3 on long trim. How many driving cycles does it take for it to adjust to normal .So far I drove the car 3 times
Hey Jimmy, usually it happens pretty quick. Sometimes it's best to clear the fuel trims and drive with it fresh.
Mike Becker, Senior Instructor
I'm a new subscriber love what you are doing. Hopefully I can catch up and earn a shirt and thanks for taking the time to share great info.
Hey Jason, welcome to the channel! Hope to see you at the live class in April!
Mike Becker, Senior Instructor
Well done good vid again on the page where you showed 450 MV rich and lean this is only on narrow band 02 sensor (nothing on the page about wide band ) I struggle with wide band still learning .great vid guys loving it 👍👍👍
Scott, you're in luck! We are going to be getting into both narrow (O2) sensors and wideband sensors in the next class. I hope next class I can fill you with all the knowledge you ever wanted on widebands!
Mike Becker-Technical Services Instructor
Thanks for the quick re
Thanks for the quick reply look forward to it the tomato sensor ,fruit or veg ,fuel or oxygen ?,after a lot of hours on iATN web site tough subject
Scott, I like that, the tomato sensor. Stay tuned my friend, next class is February 2nd at 11am and 2pm central time. Hope to see you there!
MIke Becker, Technical Services Instructor
At 33.12: it's not 260 seconds but 260 frames on the display of the snap on scanner.
Thanks for your time and effort.
Juergen, yes you're right. It is in frames not seconds, I misspoke. Sorry about that! Thanks for correcting it!
Mike Becker, Technical Services Instructor
thanks so very much for this wonderful technical talk
Thanks for watching Fru Che!
Mike Becker, Senior Technical Instructor
I have this problem since two months now, which literally drives me crazy!
About the symptoms:
Very noticeable jerking, stuttering and starting difficulties when the engine is warm/hot. Sometimes the engine won't even start at all. Engine has starting-problems.
The problem only occurs after the engine has warmed up and ONLY when starting/idling.
Error only occurs after about 10-15 minutes after the car has been shut down.
ISTA says P0172: system too rich; which means that the DME either detects too little air or too much gasoline.
So to reproduce the problem:
1. Car start perfectly when cold, not a single problem or vibration!
2. I drive half an hour normally (City/motorway)
3. Shutting the car off.
4. Waiting 15 - 20 minutes
5. Restarting the engine
6. Either the car starts with huge difficulties (sputters, shakes, jerks) OR it stalls and shuts off immediately.
So far I've replaced:
Intake manifold gaskets. (Even though this can't be the cause of the issue, since in the event of an air leak the DME would detect too much air and not too little (or am I wrong there?)
6x injectors
6x spark plugs
6x ignition coils
MAF
2 O2-sensors
2 MAP sensors
Air Filter
Engine oil change (with filter)
2 Camshaft Positioning sensors
Cleaned both Vanos-Selenoid
Crankshaft Positioning sensor
I'm struggling to understand why an intake leak would cause a rich mixture?!ISTA says I have to check the Intake system...
(I already checked 3 times!, although without a smoke-tester)
Wouldn't an air leak cause a lean condition since unmeasured air enters the engine?
OR
The ECU demands more fuel because there's an intake leak. In other words; since there is unexpectedly more air in the system, the DME has to spray more fuel to compensate the unmeasured air; hence "system too rich"? Therefore the ECU recognised that more fuel is sprayed into the engine as usual and because of this the DME says: system too rich?
-----------------------------------
Intake leak = More (unmeasured) air requires more fuel to be sprayed into the engine to compensate the "unknown" air, therefore "system too rich" --> Because the DME has to put more fuel then normal?
OR
Intake leak = More (unmeasured) air requires more fuel to be sprayed into the engine to compensate the "unknown" air, therefore "system too lean"? --> Because there is more air then normal?
Am I losing the plot here? Both make sense, but which one is scientifically and physically right?
I'm desperate and on the verge of a mental breakdown
What kind of car are you working on?
Mike Becker, Senior Instructor
GoTech
2012 BMW F10 535i xDrive 109.000 km. Check my video. I captured the problem
ruclips.net/video/lBPZEJDPXTw/видео.html
@@GoTechTraining Please I really need your help. Nobody is able to help me. Not even the dealership
It seems like gas is getting into the oil pan.
I changed the oil, and it ran fine for 3 days. Then stalling issues again.
Have you had a chance to think about it?
Or do you offer something like a TeamViewer function?
Thank you
@@Italiano9091 if your gas is mixing with oil it could be the high pressure fuel pump.
Thank you very much for the information brother. great job.
Thanks for watching!
Mike Becker, Senior Instructor
Great explanation on volumemetric efficiency
Thanks for watching Padraig!
Mike Becker, Senior Instructor
Hey Mike is good teaching me alot and it my first time watching your video.. but I can't wait to see electronics problem. Cause im not good a lil bit electronic repair or something
Hi Gerardo, thank you! I hope these videos can really help you get better at electrical and diagnostic problems! Thanks for watching.
Mike Becker, Technical Services Instructor
awesome video, great presentation!
Thanks Daniel!
Mike Becker, Senior Technical Services Instructor
Hello I hope you're doing well just would like to have an idea why the hose that goes from the canister purge valve in the Gasquet it would shrink when accelerating i would really appreciate it thanks
excellent class .
Thanks Vin Brown!
Mike Becker, Technical Services Instructor
Thank you. Really appreciate it
Thanks for watching!
Mike Becker, Senior Technical Instructor
Amazing. Thanks so much!!!
Thank you.liked this class. Learning lots.
Thanks Jesud! Glad you are learning a bunch!
Mike Becker, Technical Services Instructor
Jesud Garcia Jt y
Thank u for educating us, I always enjoyed your videos
I enjoy watching !! thanks 👍🏼
Had an envoy with a p0171 an a p0496 p0300 with long term at 35+. missing an intake vac line cap an purge valve was stuck open still checked the maf.
Hey Daniel, sounds like that thing had a bunch of issues. Got it all fixed up now?
Mike Becker, Technical Services Instructor
Once again excelent teaching congrats.
Thanks Jose!!!
Mike Becker, Senior Technical Instructor
Awesome video my 2005 mercedes e320 had a lean code what I fund is missed placed snorkle i clear the code I hope everything is fine now thank you
Awesome, gotta love an easy fix!
Mike Becker, Senior Instructor
Thank you for the knowledge
excellent instructor
Thank you!
Mike Becker, Senior Technical Instructor
Graeme in OZ
UPDATE !!!!!!!!!
This weekend may have found my issue, while checking PCV valve I noticed there was a small rubber pipe connected to the valve cover then led to PCV valve the push on connection was very easy to pull apart so I installed small hose clamp to secure it. I then connected my newly acquired Foxwell NT301 OBD2 Engine Fault Code Reader Scanner and found the instrument gave me a green tick indication when connected where as before it was an orange triangle (Yellow indicates there's an issue that has been solved). The Short Term Fuel Trim readings now look better showing around -2 banks 1 & 2 LTFT is about -9 but from what I've read this takes time to adjust after problem is resolved.
Will need to take her for a few drives to see if I have solved the 13 Year issue !!!!!!!!.
Graeme in OZ
Hey Graeme, that's awesome!!!! Yeh, LTFT will take a little time to come back to normal. Sounds like you just might have it fixed :)
Mike Becker, Senior Technical Instructor
great info!! hard to follow with the difference in time between video and audio!!
Wouldn't a vacuum leak affect both banks on a two bank engine excluding a Manifold leak on on one bank? Same on a bad injection or bad plug or coil pack on that bank?
Thank you for the video
Hey Nathan, thanks for watching!
Mike Becker, Senior Technical Instructor
I just found your site. I am new to this and it is very interesting subject. i just bought a new Altel 808 and it amazing to watch it on live data. I have a 1999 gmc k2500 5.7 I have replaced the injection spider and cleaned the carbon out of the intake. I Have changed the o2 sensors and it is telling me that i have a low heater out put on bank 1 sensor bank 2. I have looked at the wiring and it looks good. any ideas. The A/F is 14.7. o2;s are reading 450. The engine is high mileage, does not use any oil, the compression is 160 to 165. starts good and runs great. Thanks
So nice to see other guys my kind of age who’s lost when it comes to carbs! I know the basics and I know it’s ‘simple fuel control’ buts for me efi is
Ughhh carbs...hahah!
Mike Becker, Senior Technical Instructor
great video Mike
Thanks!!!
Mike Becker, Senior Technical Instructor
I had P0172 and P0175 codes on my 2013 GMC Sierra 2500hd. Once I pulled everything up on the computer, I noticed my fuel alcohol content was @ 64%. I reset that and got rid of my rich codes. Now I have a P0300 code and O2 sensor codes for both upstream sensors. Fuel trims are perfect. What could be my issue? I'm planning to check for fouled plugs and maybe bad coils but I thought it was weird I didn't have any misfires codes until after I reset the FAC and trim levels back to zero. Also all 4 O2 sensors are brand new and operate in range.
I have a p0172 code, running rich. Only went on when there was a cold snap and engine light went off when weather warmed up. By cold I mean -30c then warming to -6c. Could a sensor freeze?
Very useful information sir thank you
Sir I have Chevy suburban 2007 and I'm getting codes p0172 and p0175 system too rich on both banks and ratio is showing short fuel trim at 0 and long fuel trim at -25 what do you suggest me to do first
Thank you for watching A Rahman! On your suburban, these were very common to run into fuel composition calculation issues. There should be a PID on your scanner saying ethanol content. Verify that seems right. if you are running standard pump gas we usually look for 5-10%. Anything higher than that can give you issues. Ethanol requires higher fuel volume which could be exactly why your truck is running rich.
Mike Becker, Senior Technical Instructor
Very informative. Thanks for the taking the time. You teach a great class. Your step by step process is unmatched. Thanks for passing the knowledge to us all.
A RAHMAN fuel pressure regulator.
Dona fuel pressure leak down test. Must hold 55psi for several minutes after key off.
wow your the best man, good job
Thanks Raed Alyamani! Glad you enjoyed the video!
Mike Becker, Technical Services Instructor
Great after 6 years 🇯🇲
Hey, thanks for the video. Very helpful. My shogun sport v6 has codes P0170 and P0173, both fuel trims. It seems to be running fine except a slight change in idling speed every minute or so (from 1000 to 700ish RPM). The previous owner has changed an o2 sensor (top of cat) but the 'check engine light' is back on. I've unplugged the MAF sensor and the idling speed increases, then goes back to normal once plugged back in. That's all I've done so far.
Any ideas appreciated! Bit of a head scratcher 🤔
Hey Mark, Do you have a scan tool that can watch data? I'd like to see what the fuel trims are reading at idle and at a moderate load. There are a lot of possibilities to what could cause this issue.
Mike Becker, Senior Technical Instructor
@@GoTechTraining thanks Mike, yes I have the torque light obd2 thing I'll take some screenshots and send them to you if you like? There's 4 sensors per bank, I'll try and get them on the same screen. What's your email?
Sure, send them to MCBecker@NGKSPARKPLUGS.com
@@GoTechTraining emailed you 👍
I've have learn a lot from watching this video thanks guys Just one question. My car was running lean on bank 2 due to a vacuum leak. 21 short term and 16 long term during idle Well I got that fixed and now its running rich each time I accelerate. Like sometimes 8- to 13- on the long trim and 5 to 8- on short trim. The fuel trims are okay during idle Is there anything I missed? or is it normal for the car to run very rich while accelerating it.
Did you figure it out?
I have 2004 mini cooper 1.6l r50
check engine light on and code p2097 post catalyst fuel trim system too rich bank1 what should I do? somebody said I should change a oxygen sensor... but which one should I one on the hood or one under bottom of the car?
It's a great tutorial!!
Thank you very much!!!
Mike Becker, Senior Instructor
thanks for this video
My car is a 02 chevy prizim. I keep getting a po 420 cat system low efficiency code.
I have already replaced the following. The upper and lower purge solenoid was replaced, Replaced the charcoal canister, changed the up and down stream 02 sensor. I replaced the mass air flow sensor. I replaced the cat. I also checked all the evap hoses and their is no leaks. I also changed all the spark plugs and pick up coils.
I'm at my witts end and trying to figure out. Why it keeps giving this code. And keep blowing the cat, purge solenoids and pick up coil.
I also did a smoke test and it well sealed.
Thank you guy’s for your patience and knowledge, where do I join classes? You guy’s should teach classes online or thrue zoom
Very informative... thanks for taking the time.
Thank you Mike!
Mike Becker, Senior Technical Instructor
@ThePariss333 Well, good thing you can skip around in the video then...or play at 2x speed!
Mike Becker, Senior Technical Instructor
What about a failed spark plug boot or leak in hose to evac.
Good job thank you
Thanks for watching Khaled!
Mike Becker, Technical Services Instructor
hi, i,m new subscriber, great video! my car is nissan skyline 300gt 2002 year. lambda is 1,017, but CO is very high 1,57-1,76. what is possible causes? thanks!
Great thorough and informitive class.
BTW, how's life in fondy?
Hey Geoffrey, thanks for watching! Life in Fondy is....well life in Fondy, haha! Plenty of road construction lol.
Mike Becker, Senior Instructor
I need y’all‘s help I have a 97 Toyota forerunner 3.4 L that I’m having a major Rich issue and every time I try something it does not work. I have replaced my O2 sensors, engine coolant temperature sensor, injectors, mass airflow sensor, fuel pressure sensor and about to change my fuel pressure regulator,fuel filter all vacuum lines as well as PCV valve, throttle position sensor. I got a new IAT but the vacuum tube on it fell off so I put the old one back on. I’ve done a compression test and all are within spec new spark plugs and coils and have swap the wires out with some wires that I had from before just to see if the ones that were on it are bad. The plugs are the dual tipped plugs that are recommended. There is a colder intake on the system which has been working fine on it for the past five years. All my fuses and relays check out yeT I am still getting a -20 something for my short term -17ish for my long-term. I get a misfire cylinder one error code but when I look at cylinder one misfire Count is less than 10 in the span of an hour. If I hit the throttle short term will zero out for a few seconds and then slowly Drop back to -20. When the engine is cool and I start it the mass air will be pulling close to 10 psi but after it Gets done with its warm-up cycle it drops down to around 3 sometimes even 2 1/2 psi. My injection it’s so low that the car almost stalls out somewhere in the upper 2gpm area. And when I first start the vehicle after it cooling down for a while it takes a long time to start. Somebody help me please
I have a car that can run on petrol and on LPG. When run on petrol I get HO2S 0.3V, stuck lean. When run on LPG, I get HO2S 0.7V stuck rich.
Also HO2S is brand new and OEM. Using OBD reader,HO2S voltage is constant, it is not moving from rich to lean.
Any idea what to look for?
Numero uno en enseñar gracias ( thanks) Juan
Saludos Juan y muchas gracias por el comentario, no te pierdas las proximans clases van estar muy interesantes. Fritz Fuchs Instructor de Servicio Automotriz.
Ayy I got a GTO to lol but I’m watching this vid for my Ctsv
We have sold the GTO now. IT was time for it to go away. Poor thing sat most of the time.
Mike Becker, Senior Technical Instructor
How do I delete my 02 sensors
I got a question so I have a 2003 Ford Mustang 3.8 v6 and my LTFT B1 and B2 are both at -99.5 but no codes at all and engine seems to be running fine what’s going on with it?
Awesome video
Do you have any videos that go over closed loop fault? I have a 03 Ford expedition that is stuck in cl fault. I don't know how to approach this issue
Robert, closed loop fault is the vehicle not able to obtain closed loop. Do you have any trouble codes?
Mike Becker, Senior Technical Instructor
P304 code & P0174. Have 2009 Ford escape 3.0l. How does the miss fire possibly cause my lean code?
CEL TOO RICH TO LEAN AND MISFIRES.
I changed maf sensor n air filters. Light still on
Then Changed all Fuel injectors light still on.
Changed all spark plugs and all oxygens sensors light still popped back on.
What could this be please help! I’m tired of fixing stuff that probably wasn’t the answer. Last hope was the oxygen sensors once they were out they were fried bad . Once I clear the codes rev up and drive it handles fine. But once sitting idled it sputters
My car is LTFT -10.3 ? but everything like 02 doing as it should thorts pls
Hey KComputers, curious, what are you STFT when the LTFT is -10.3? Are they hovering 0? A -10 trim shows you are running slightly rich. What kind of car is this on?
Mike Becker, Senior Technical Instructor
My 03 F150 Lariat 5.4 keeps giving me a P0401 code and negative trims around -12 to -16. I have replaced EGR valve, DPFE sensor (and hoses), EGR tube, EGR vaccum solenoid, IAC valve, plugs, coils, intake manifold, fuel injectors, and EVAP purge solenoid...
to anyone watching this in the future and notices the audio is off, a way to get around this is 2 have two youtube tabs open of this video, one to watch on mute, and another to have audio playing and minimized. the time difference is ~9:40 seconds. so fast forward one to that time mark and then hit play on both of them as quickly as you can. was driving me crazy.
My question about the Lambda reading on a scan tool is , for an example, 1.2 on your lambda chart on your video training, when you read this value on a scan tool , is the computer on your car taking fuel away because the fuel trims rich ? If someone can answer the question I would be thankful!
Hi I need some help I have p1137 add fuel bank 1 rich. I have put all new parts to do with that code still comes up.
I am facing issues with p0172 ... I changed fuel injectors, air fuel ratio sensor, o2 sensor downstream, ignition coils and sparks
Thanks
Great vid!! I get this code every winter and only in winter. I have absolutely, no symptoms - pont 08 vibe, purrs like a kitten. Chkd for vac leaks, intake gasket, gas cap and o2 sensor. All good. Thinkin maybe fuel injectors or fuel pressure issues. Giv me yur critique!😩
RM.
Hey Rudy, thanks for watching! The Vibes were SUPER common for intake gaskets to leak only when the engine is cold. Has yours ever been replaced?
~Mike
@@GoTechTraining No, it hasn’t. Thanks
Hi guys. I have watched a ton of your videos and loads others and still stuck. i am working on a 2001 corolla.1.8l..174,000 miles. code is a po171..lean bank 1. I have high fuel trims. shrt sometimes maxs out at 19.5% and lngt is always high 15 to 20 % +. Trims will drop at 2500rpm...maf reading about 1.8 at idle and rises up to 8 or 9 at 2500rpm. I have done a smoke test and could not detect a leak. o2s b1 wave looks ok, average about .485, and does switch wave from .1 to about.800...I dont think its fuel delivery because the trims drop at higher rpms. . vacuum tested about 21 with needle bounce, possible valve guides leak?
Freeze frame showed Fsystem..cl...ECT 179Deg,,, shtft -2.2,,, lgtft 34.4%,,,rpm, 710,,,,,IAT 95Deg,,,
I am about to start throwing money at it. not sure what else to do. i need the car fixed to pass emmisions for my daughter to start college. Live in tx and have to pass emmisions. Looking at new maf,o2sensors. Already changed pcv and air filter and cleaned the maf.Help !!
Question
I replaced the intake manifold gasket and Throttlebody gasket and replaced the egr valve and evap and still getting a lean code what can it be
Have you checked fuel pressure? maybe it's low? Maybe there's water in the tank?
Mike Becker, Senior Technical Instructor
I had a throttle body relearn done to fix the constant problem after cleaning it. I think I may have made a mistake I did a fuel composition reset using X431 on my 2011 5.3 flex fuel suburban , currently have e85 in my tank. Now I have 2 code errors p0171-00 and p0174-00 fuel trim lean system lean bank 1 and 2. Did I do something wrong? I would appreciate any help what to do and proceed. Thank you
Hi Ken,
Your vehicle uses an algorithm to calculate fuel ethanol %. When you reset the fuel composition, it defaults to >10% ethanol. Since E85 burns at closer to a 10:1 ratio compared to Gasoline at 14.7:1 it will cause your vehicle to run lean and set those codes. The only way to fix this issue without measuring the ethanol content and re-programing the ECM. Is to run the tank empty and put in a tank of regular 10% or less ethanol in and do the fuel composition reset again. This way the ECM learned percentage will match the fuel in the tank. Unless you manually drain the tank, you may have to do this twice to get the % back to normal. Hope this helps, Thanks
Ryan W, Technical Instructor
Question: I have a 2013 F30 BMW 328i. I got codes P0171 and P0172 at the same time. The codes contradict each other. My "start/stop" feature in the car doesn't work anymore. Any idea what the issue is?
Did you ever find out the problem? I’ve been looking everywhere for this, but I have not had luck.
So if my 03 Toyota Corolla S is giving me P0420 and p0446 and p0440 and p0171. Should I replace both o2. The car has like 350000 miles lol so I’m guessing everything is old or shot and needs to be replace... thank u
Can y'all do some post carb, pre obd2 fuel trim videos PLEASE!? Reading blinking lights sucks! Do u have insight?
My issue on a poor random idling 92 Nissan MT KA24E KC XE no CEL per Nissan. I'm sick of it becoming this parts cannon.. still have all original parts on hand.
Very good information great class. My shirt size is Medium.
Hey Tony, thanks! Sorry we only send out shirts when the class is live. Thanks for answering though!
Mike Becker, Senior Technical Instructor
I have a 2002 Dodge Neon SE, P0172 code with 160,000 miles. No vacuum leaks, new plugs, new map sensor, new IAC, new O2, and new injectors. Still have the code after reset. Can you guys help? I`m ready to push my daily driver off a cliff. Fuel trims are pegged at -25. codes were reset after each part was replaced. Car will not pass Pa. inspection with MIL on.
My 2010 Chevy malibu I have the po172 code engine will nit start the oil has gas in it the MAP sensor checked out ok any ideas that would make bank 1 rich
How do you check for a p1093?
I have a Lexus is350 showing p2238, I have replaced the O2 sensor the dtc does not go away. After checking the fuel trims I have 0 on both on short fuel trim but on the long fuel trims they are -3 and -6, any idea about what is causing it?
Hey Robertoyzayda, you're fuel trims seems pretty normal. Could maybe just be a bad sensor?
Mike Becker, Senior Technical Instructor