Thank you for taking the time to make this video. You explained a LOT to me. I bought a code reader and it was all secret code. Now I have a basic understanding of it and little problems to look out for. I wish I could thank you personally. Videos like this one are rare.
Tha k you for posting this bro i just followed the same thing you did and found that my maf sensor was just dirty and needed to be cleaned. You are the man gained a new follower! 👌🏾
this was very helpful thank you! i bought the smoke tester, it's great. found a tiny leak where the intake boot clamps to the throttle, but no change after that was tightened. did a water spray all over the intake manifold gaskets and no steam out of the exhaust. smoke tested the exhaust as well and nothing. my long term fuel trim is around 18% on both banks at low load or idle and drops to around 10% under medium throttle. i did notice my intake air temp was considerably off from actual air temperatures and very slow to respond to changes ( from sitting in a parking lot, hot start on a hot day, to diving down the highway at 55, it changed very slowly and never read the right temp, was always high by about 5-10%) new maf on the way, i think mine is original, 20yrs old, 264k on it. cleaning it didn't have any impact.
No shit! This hole time it’s been a check valve. And I’ve been debating on getting a new fuel pump. Texted it and it’s was 55. But after 45 seconds to a minute it would slowly start moving down. And a bitch to start on cold mornings. Well I know what I’m replacing this weekend. Thanks!!!
Thanks for posting the video. 2004 Yukon 5.3L threw a MAF sensor code, so I replaced with a Delphi MAF just this past week. Code cleared, and now I have 171 and 174. If I understand your comments, with more driving is it possible the fuel trim numbers settle out to be in spec and stops throwing those codes?
I’m having the same problem now on a 2005. Truck has New MAF, CAM SENSOR, and NEW EVAP system with no CHECK ENGINE light. Problem I’m having is that it dies while sitting at the traffic light or stumbles when on the highway. I have 60 lbs of pressure on the fuel pump even when it shut off. I’m leaning more to the fuel pump now
I had something similar to this happen to me with a 3.6l Bonneville. Sit a a light and engine would die. Had the throttle body cleaned and never happened again
I FOUND IT I GODDAMN FOUND IT! It was the FUEL PUMP RELAY! That S.O.B had burn spots on each side. Evidently it kept tripping after it gotten hot and would shut down but start back up. I switched it out and was riding for two weeks and the Tranmission failed LAST WEEK 😂😂😂😂😂
I have these codes and ltft numbers when I TAP and release the throttle the truck revs up and stays at the high rpm on its own for a second or two then settles.
@@jbags091992 replaced the hoses that were cracked and brittle but it didn’t change the fuel trims. I ordered a throttle body and swapped and my trims are now better, my tb was pretty gunked up. unfortunately now I’m have a high rpm issue with the new tb swap. common with cleaning or replacing tb’s but I’ve done everything TH-cam has to offer and it’s still shooting up to 2k rpm.
Means the opposite, high trims mean it’s low on fuel, low trims / negative means it’s good or too much on fuel. Fuel delivery issues (pump etc) will cause high trims under load, they will never be bad at idle and fix with load to my understanding. Vacuum leaks will cause high trims at idle, and likely correct under load. Such as your issue described
You should have pulled up the data pid for the mass airflow sensor and see what the grams per second flow reading was, that might have told you something. Was that new sensor after market or dealer? great vid other wise.
I replaced the Maf sensor, the intake gasket, replaced a PCV valve and the tubing and there’s not any other leak, now I have a P0174 code. Should I have to replace the oxygen sensors? Help!!! I already spent $700 pus the parts.
There's some decent info buried in here, but the terms and language being used to describe some of it is wrong. Examples... Fuel trim is almost NEVER zero Fuel trim at idle isn't terribly helpful for a lot - trims under load matter much, much more - especially long-term trims. Specific issues with the 2014-2018 high pressure fuel pump design causes fuel leaks directly into the valves which causes a "rich" condition. This will set the MIL and DTC's but the only way to diagnose the bad LTFT's is while actively driving the vehicle. "Within 5% of zero" should like have been described as "within a range of plus or minus 5%" as "5% of zero" is zero...
I'm grateful for your detailed explanation and corrections on the terminology regarding fuel trim. Your input helps improve the accuracy of the content shared.
This is the smoke leak checker I got on Amazon amzn.to/4ccprqC. It works great!
Thank you for taking the time to make this video. You explained a LOT to me. I bought a code reader and it was all secret code. Now I have a basic understanding of it and little problems to look out for. I wish I could thank you personally. Videos like this one are rare.
excellent info! good tip re removing the oil cap for the smoke test
Tha k you for posting this bro i just followed the same thing you did and found that my maf sensor was just dirty and needed to be cleaned. You are the man gained a new follower! 👌🏾
THANK-YOU BROTHER , STAY AWESOME...GOD LOVES YOU !!
If you are getting a P0171 code but if it was a fuel pressure problem wouldn't you get some kind of fuel pressure problem code as well?
nonflammable brake cleaner? id think youd want to to react, right?
this was a great explanation of troubleshooting...thanks for doing that, now to go put it in action
How much would it coast to fix those 2 codes?. P0171 an p0174
this was very helpful thank you! i bought the smoke tester, it's great. found a tiny leak where the intake boot clamps to the throttle, but no change after that was tightened. did a water spray all over the intake manifold gaskets and no steam out of the exhaust. smoke tested the exhaust as well and nothing. my long term fuel trim is around 18% on both banks at low load or idle and drops to around 10% under medium throttle. i did notice my intake air temp was considerably off from actual air temperatures and very slow to respond to changes ( from sitting in a parking lot, hot start on a hot day, to diving down the highway at 55, it changed very slowly and never read the right temp, was always high by about 5-10%) new maf on the way, i think mine is original, 20yrs old, 264k on it. cleaning it didn't have any impact.
Did it fix it?
@cesarcastillo809 new maf sensor did fix it!
No shit! This hole time it’s been a check valve. And I’ve been debating on getting a new fuel pump. Texted it and it’s was 55. But after 45 seconds to a minute it would slowly start moving down. And a bitch to start on cold mornings. Well I know what I’m replacing this weekend. Thanks!!!
Thanks for posting the video. 2004 Yukon 5.3L threw a MAF sensor code, so I replaced with a Delphi MAF just this past week. Code cleared, and now I have 171 and 174. If I understand your comments, with more driving is it possible the fuel trim numbers settle out to be in spec and stops throwing those codes?
I got a 5.3 Silverado and just replaced Maf and getting the same code, did u figure it out?
@@tasaiyaxaypanya3140Same thing did you find a fix
any fix?
Fix?
Excellent video my friend, thank you so much for this A+ lesson 👍🏽👍🏽
I’m having the same problem now on a 2005. Truck has New MAF, CAM SENSOR, and NEW EVAP system with no CHECK ENGINE light. Problem I’m having is that it dies while sitting at the traffic light or stumbles when on the highway. I have 60 lbs of pressure on the fuel pump even when it shut off. I’m leaning more to the fuel pump now
I had something similar to this happen to me with a 3.6l Bonneville. Sit a a light and engine would die. Had the throttle body cleaned and never happened again
@@allenbatts7971 I cleaned that too
I FOUND IT I GODDAMN FOUND IT! It was the FUEL PUMP RELAY! That S.O.B had burn spots on each side. Evidently it kept tripping after it gotten hot and would shut down but start back up. I switched it out and was riding for two weeks and the Tranmission failed LAST WEEK 😂😂😂😂😂
Damn i hope thats mine i got same issue right now@traifields846
I have these codes and ltft numbers when I TAP and release the throttle the truck revs up and stays at the high rpm on its own for a second or two then settles.
Did you figure out what caused it, mine does the same thing
@@jbags091992 replaced the hoses that were cracked and brittle but it didn’t change the fuel trims. I ordered a throttle body and swapped and my trims are now better, my tb was pretty gunked up. unfortunately now I’m have a high rpm issue with the new tb swap. common with cleaning or replacing tb’s but I’ve done everything TH-cam has to offer and it’s still shooting up to 2k rpm.
@@justinlong977 Im having the same problem brother! Im going to try what this guy did but if you find anything please let me know!
@@Dyllanman it seems to have settled down a lot, I guess weeks of driving did it?
So if I accelerate and my bank 2 trim goes down from 20 to 0 does that indicate bad fuel pump?
No. That seems to indicate that your air fuel mixture balances out unde load or higher rpm. I'd lean more towards a vacuum leak or a MAF
Means the opposite, high trims mean it’s low on fuel, low trims / negative means it’s good or too much on fuel. Fuel delivery issues (pump etc) will cause high trims under load, they will never be bad at idle and fix with load to my understanding.
Vacuum leaks will cause high trims at idle, and likely correct under load. Such as your issue described
You should have pulled up the data pid for the mass airflow sensor and see what the grams per second flow reading was, that might have told you something. Was that new sensor after market or dealer? great vid other wise.
We put a denso MAF - I've had pretty good luck with this brand. Wouldnt recommend after-market
You have a fuel pressure issue I am shocked you did not see it.
On the 5.3 its almost always header bolts snapped , loose, broken to the cylinder heads. Be ready for the fight of your life 😢
Great video man
Mine will fire and immediately die several times from a cold start.
Excellent
I replaced the Maf sensor, the intake gasket, replaced a PCV valve and the tubing and there’s not any other leak, now I have a P0174 code.
Should I have to replace the oxygen sensors?
Help!!! I already spent $700 pus the parts.
I have po171, which is the other bank lean. I can't figure it out either.
You figure it out? I have a p0171 only code, gonna change the o2 sensors
@@alexlsx8187 No. Not yet.
I have both codes and replace all O2 sensors fuel pump throttle body purge valve and mass air flow
@@zachparadis8455did you have any luck yet? I’m desling with the same issue plus knock sensors both banks.
There's some decent info buried in here, but the terms and language being used to describe some of it is wrong. Examples...
Fuel trim is almost NEVER zero
Fuel trim at idle isn't terribly helpful for a lot - trims under load matter much, much more - especially long-term trims. Specific issues with the 2014-2018 high pressure fuel pump design causes fuel leaks directly into the valves which causes a "rich" condition. This will set the MIL and DTC's but the only way to diagnose the bad LTFT's is while actively driving the vehicle.
"Within 5% of zero" should like have been described as "within a range of plus or minus 5%" as "5% of zero" is zero...
I'm grateful for your detailed explanation and corrections on the terminology regarding fuel trim. Your input helps improve the accuracy of the content shared.