Ltrims Way Lean, O2's Lean/Rich, SES Light Code PO135
05-21-2002, 08:55 AM
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Ltrims Way Lean, O2's Lean/Rich, SES Light Code PO135 I NEED HELP!! Just did the following. MTI S2 Heads, C2 Cam, MTI Programing, LS6 intake, Whisper MAF ends, FTRA, I had SLP Headers, dual cutouts, ORP. I also just bought Autotap.
After install I got a code DTC P0171 Fuel Trim System Lean Bank 1 and PO174 Bank 2
I adjusted MAFT to 20% rich and now Lterms are around 14-16. ???????? Still lean with no further adjustment on MAFT
MAFT set to 5% rich on WOT and O2's read .86 on Drivers side, .93 on Passanger side. Lean on one side and rich on the other?????
Also throwing code P0135 HO2S Heater Performance Bank 1 Sensor 1 and PO155 bank 2
I just ran a 11.6 @ 117 so the car is running great... are the O2's bad????
After install I got a code DTC P0171 Fuel Trim System Lean Bank 1 and PO174 Bank 2
I adjusted MAFT to 20% rich and now Lterms are around 14-16. ???????? Still lean with no further adjustment on MAFT
MAFT set to 5% rich on WOT and O2's read .86 on Drivers side, .93 on Passanger side. Lean on one side and rich on the other?????
Also throwing code P0135 HO2S Heater Performance Bank 1 Sensor 1 and PO155 bank 2
I just ran a 11.6 @ 117 so the car is running great... are the O2's bad????
05-21-2002, 11:45 AM
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Re: Ltrims Way Lean, O2's Lean/Rich, SES Light Code PO135 If I understand you correctly you JUST had this work done which included PCM programming, thus I would go back to that shop and tell them to fix the problems for being 25% plus lean is uncalled for.
WIth tuning there should be no reason to even need a MAFT.
Keep in mind that when you fool PCM with a MAFT, it takes at least 1 hour or more driving time for PCM to readjust the LTFTs, so maybe you need more engine run time.
Check you fuel rail pressure and see if it is around 58 lbs at idle to know if there is a fuel pump or injector issue.
Use the scanner and see what the injector pulse width and duty cycle is like, if your seeing pulse width of 18 plus mSecs then it truely is running lean. Also monitor both LTFTs and the higher the postive numbers are, the leaner the engine is running.
Go back to that shop for running that lean is going to cause long term damage.
Heaters of 02s only work when engine is cold and would not cause running so lean once engine is at temps and if O2s were totally bad you should also get other 02 DTCs.
Via scanner do the I/M 240 tests and see what state heaters and O2s are in, they should be in a completed state, if it says not completed, that means they failed the tests or have not been tested long enough to get to a completed state.
If you believe the S1 O2s ( upstream of cats) are bad, swap them with the S2 ( downstream) 02s and see if there is any change.
Being atap is a slow slug, you can see differences in B1 ( left head) to B2 ( right head) because atap cannot keep up and misses PCM cycles.
WIth tuning there should be no reason to even need a MAFT.
Keep in mind that when you fool PCM with a MAFT, it takes at least 1 hour or more driving time for PCM to readjust the LTFTs, so maybe you need more engine run time.
Check you fuel rail pressure and see if it is around 58 lbs at idle to know if there is a fuel pump or injector issue.
Use the scanner and see what the injector pulse width and duty cycle is like, if your seeing pulse width of 18 plus mSecs then it truely is running lean. Also monitor both LTFTs and the higher the postive numbers are, the leaner the engine is running.
Go back to that shop for running that lean is going to cause long term damage.
Heaters of 02s only work when engine is cold and would not cause running so lean once engine is at temps and if O2s were totally bad you should also get other 02 DTCs.
Via scanner do the I/M 240 tests and see what state heaters and O2s are in, they should be in a completed state, if it says not completed, that means they failed the tests or have not been tested long enough to get to a completed state.
If you believe the S1 O2s ( upstream of cats) are bad, swap them with the S2 ( downstream) 02s and see if there is any change.
Being atap is a slow slug, you can see differences in B1 ( left head) to B2 ( right head) because atap cannot keep up and misses PCM cycles.
05-21-2002, 04:20 PM
#3
Re: Ltrims Way Lean, O2's Lean/Rich, SES Light Code PO135 I didn't think heads lean it out that much,my b1 cam might have leaned me out a little bit ,headers are supposed to richen it and those maf ends will really lean it.hmm...when are you looking at your ltrims..I only look at them at part throttle acceleration...they should be zero at wot and idle don't count either..mine are like
-4 to zero right now..the recommended amount by several guys on the boards.I also had my maf up
two notches richer with my cam and current mods.no heads,or headers though and I run the gms maf.I then installed my hpp tuning for more timing and had to crank up my maf to 5 notches up wot..but my base is still zero.car runs fine..no knock retard..feels great..
I would also go back to stock maf ends for now.
You might need bigger injectors now..think 30svo would help and you should check fuel pressure,fuel filter also.
-4 to zero right now..the recommended amount by several guys on the boards.I also had my maf up
two notches richer with my cam and current mods.no heads,or headers though and I run the gms maf.I then installed my hpp tuning for more timing and had to crank up my maf to 5 notches up wot..but my base is still zero.car runs fine..no knock retard..feels great..
I would also go back to stock maf ends for now.
You might need bigger injectors now..think 30svo would help and you should check fuel pressure,fuel filter also.
05-22-2002, 12:21 AM
#4
Re: Ltrims Way Lean, O2's Lean/Rich, SES Light Code PO135 Sounds like it could be a mechanical failure. Double check the intake system from the MAF back to ensure there are no leaks. Unmetered air entering the system will cause the car to be real lean.
Did MTI think you were swapping to bigger injectors? If they changed the PCM for bigger injectors but you didn't swap, that could cause it to run lean.
Are you using a ported MAF? if yes go back to stock.
Did MTI think you were swapping to bigger injectors? If they changed the PCM for bigger injectors but you didn't swap, that could cause it to run lean.
Are you using a ported MAF? if yes go back to stock.
