P0174 Code, only when hot out.....
P0174 Code, only when hot out..... I drive to work in the morning and everything is perfect. STFT's ~ 0, LTFT's low single digits, all O2 sensors switching normally. In garage all night, ~ 75F.
Go to drive home, sits in sun all day, ~ 93F, Bank 1 normal, Bank 2, STFT >50, LTFT 25, O2B2S1 never goes over 0.2V. Tail pipes black, runs like crap, idles like big cam.
Any ideas?
Already replaced, wires, plugs, coil packs, had injectors cleaned and flow tested, replaced pcv system, all O2 sensors, no vacuum leaks, no exhaust leaks.
Jon
Go to drive home, sits in sun all day, ~ 93F, Bank 1 normal, Bank 2, STFT >50, LTFT 25, O2B2S1 never goes over 0.2V. Tail pipes black, runs like crap, idles like big cam.
Any ideas?
Already replaced, wires, plugs, coil packs, had injectors cleaned and flow tested, replaced pcv system, all O2 sensors, no vacuum leaks, no exhaust leaks.
Jon
I had that code for the longest time on my 1997 v6. Turns out I had a weak fuel pump that was only pushing 22psi. Replaced it and the problem went away.
Check and clean your MAF first though, if it still comes back, check your fuel pressure. Could be other things too.
Check and clean your MAF first though, if it still comes back, check your fuel pressure. Could be other things too.
Same for the MAF, would not affect only only bank.
Jon
swap O2 sensors from driver to pass side and see if code jumps.
after that:
1. Check for 55-60 PSI fuel pressure. The pressure regulator is in the fuel tank, so this pressure should be steady.
2. Verify there are no vacuum leaks.
3. Clean the Mass Air Flow (MAF), retest.
4. Disconnect the MAF, retest.
after that:
1. Check for 55-60 PSI fuel pressure. The pressure regulator is in the fuel tank, so this pressure should be steady.
2. Verify there are no vacuum leaks.
3. Clean the Mass Air Flow (MAF), retest.
4. Disconnect the MAF, retest.
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from what you said in original post only one bank rules out MAF and fuel pressure- anything that is common to both banks. And, you're seeing the pcm detect what it thinks is a lean condition so fuel trims go super positive and it dumps a ton of extra fuel on bank 2 only. Now if there were a real lean condition then that extra fuel to a point would make the engine run better but it's not. You say runs like crap and tail pipes black so that tells me it's a perceived lean condition when there isn't one and the pcm is commanding extra fuel causing a rich problem on bank 2. so if that's the case you should also be able to verify that by inspecting spark plugs as soon as possible after it happens, they should be black and dry fouled.
since it sounds like you have the ability to monitor real time data, and hopefully record and look at freeze frame data, i would try monitoring things when you start the car knowing when it will happen to help see what might be causing it and when. easiest thing at this point i think is swapping front O2's to see if the problem then happens on bank 1 and gives you P0171, if it does then suspect a bad and very weird o2 sensor. if it continues to happen on bank 2 then i think you may be looking at a bad pcm. i assume you have not modified you pcm and put an aftermarket tune on it and that it is untouched.
since it sounds like you have the ability to monitor real time data, and hopefully record and look at freeze frame data, i would try monitoring things when you start the car knowing when it will happen to help see what might be causing it and when. easiest thing at this point i think is swapping front O2's to see if the problem then happens on bank 1 and gives you P0171, if it does then suspect a bad and very weird o2 sensor. if it continues to happen on bank 2 then i think you may be looking at a bad pcm. i assume you have not modified you pcm and put an aftermarket tune on it and that it is untouched.
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Verdad Gallardo from what you said in original post only one bank rules out MAF and fuel pressure- anything that is common to both banks. And, you're seeing the pcm detect what it thinks is a lean condition so fuel trims go super positive and it dumps a ton of extra fuel on bank 2 only. Now if there were a real lean condition then that extra fuel to a point would make the engine run better but it's not. You say runs like crap and tail pipes black so that tells me it's a perceived lean condition when there isn't one and the pcm is commanding extra fuel causing a rich problem on bank 2. so if that's the case you should also be able to verify that by inspecting spark plugs as soon as possible after it happens, they should be black and dry fouled.
since it sounds like you have the ability to monitor real time data, and hopefully record and look at freeze frame data, i would try monitoring things when you start the car knowing when it will happen to help see what might be causing it and when. easiest thing at this point i think is swapping front O2's to see if the problem then happens on bank 1 and gives you P0171, if it does then suspect a bad and very weird o2 sensor. if it continues to happen on bank 2 then i think you may be looking at a bad pcm. i assume you have not modified you pcm and put an aftermarket tune on it and that it is untouched.
since it sounds like you have the ability to monitor real time data, and hopefully record and look at freeze frame data, i would try monitoring things when you start the car knowing when it will happen to help see what might be causing it and when. easiest thing at this point i think is swapping front O2's to see if the problem then happens on bank 1 and gives you P0171, if it does then suspect a bad and very weird o2 sensor. if it continues to happen on bank 2 then i think you may be looking at a bad pcm. i assume you have not modified you pcm and put an aftermarket tune on it and that it is untouched.
Only thing I have not ruled out is an exhaust leak pre O2 on bank2. Problem is, why would this only be a problem when its hot outside, manifold gets to 500+ degrees anyway.
Appreciate your input.
Jon
I got the code for only one bank when I had my MAF issue. I think the reason is that no two O2 sensors are created equal.
This would probably be very telling. If the same bank stays as the issue after this, then maybe its a bad injector?
(I'd still try unplugging the MAF, (free) regardless to see what happens before doing something more costly.)
(I'd still try unplugging the MAF, (free) regardless to see what happens before doing something more costly.)
Joined: Nov 2001
Posts: 34,627
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From: Schiller Park, ILL Member: #317
I wonder if there is a wiring harness issue of some sort..... something that is borderline but then becomes more pronounced with increased resistance due to heat? Seems low probability, but if you have tried all other suggestions in this thread then there is little else to look at.
now that i think about it a MAF like you said could cause single bank issues, I had that happen on my truck and i'd sometimes get just p0171, or both p0171 & p0174 but i would also get a random p0101. but in my case i never had any engine problems and it ran great. with a maf though you can see what it's reporting with a handheld showing real time data which would help to rule it out. in disconnecting a MAF does it cause the pcm do go into open-loop mode and also ignore the O2 sensors? if so then disconnecting the maf then having the engine run well might be a false result.
i remember reading in motor magazine a tech article and common causes of lean conditions are the emission system pumping air into the exhaust, solenoids that open/close to seal things like the AIR pump don't seal and can leak. since you are on bank2 passenger side, look at what might inject air into the exhaust. i know there are (on my 2002 anyway) the AIR check valves on both sides that are on a tube from the exhaust manifold which i believe has cold air pump into the manifold upon startup to help light off the cats faster. i would consider replacing both check valves, they are like $10 each from autozone and easy to do and they all eventually wear out. mine went out and i got a specific code for them- p1416, but never had an issue running other than light on the dash. in your case i would trace back to the air pump and verify the solenoid is closing and the air pump turns off. you should might be able to see if the air pump is turned on with a scanner when the problem occurs.
https://ls1tech.com/forums/general-m...lve-where.html
i remember reading in motor magazine a tech article and common causes of lean conditions are the emission system pumping air into the exhaust, solenoids that open/close to seal things like the AIR pump don't seal and can leak. since you are on bank2 passenger side, look at what might inject air into the exhaust. i know there are (on my 2002 anyway) the AIR check valves on both sides that are on a tube from the exhaust manifold which i believe has cold air pump into the manifold upon startup to help light off the cats faster. i would consider replacing both check valves, they are like $10 each from autozone and easy to do and they all eventually wear out. mine went out and i got a specific code for them- p1416, but never had an issue running other than light on the dash. in your case i would trace back to the air pump and verify the solenoid is closing and the air pump turns off. you should might be able to see if the air pump is turned on with a scanner when the problem occurs.
https://ls1tech.com/forums/general-m...lve-where.html
i know there are (on my 2002 anyway) the AIR check valves on both sides that are on a tube from the exhaust manifold which i believe has cold air pump into the manifold upon startup to help light off the cats faster. i would consider replacing both check valves, they are like $10 each from autozone and easy to do and they all eventually wear out. mine went out and i got a specific code for them- p1416, but never had an issue running other than light on the dash. in your case i would trace back to the air pump and verify the solenoid is closing and the air pump turns off. you should might be able to see if the air pump is turned on with a scanner when the problem occurs.
https://ls1tech.com/forums/general-m...lve-where.html
https://ls1tech.com/forums/general-m...lve-where.html
Jon
I may try propane gas for the test.
Jon
