3800 O2 - LTFT - STFT

[J.E.T.]

I'm continuing to get my car running in optimal condition. It runs great at speed - idles ok now (replaced EGR tube) - still whistling a little - no biggie (I need to take the sc off and look around).

The problem is that my fuel trims are NOT moving. They are pegged at LTFT 16.4 and STFT 20.4. I've replaced the MAF, and the 02 (Bosch brand) sensor twice. The O2 4 pin connector had a little corrosion on one pin, but I cleaned that off with contact cleaner and then used battery anti corrosion spray. I do have an A/F gauge, but it doesnt make a difference whether it is connected or not. It is tapped on the car harness side, not the 02 harness.

After a few key cycles, the SES light comes one. If I recall correctly: P0132 - NO 02 signal or low 02.

Ironically, the car runs GREAT. No KR with 3.1" pulley but I've only taken it to near WOT with 10psi of boost. I'm hesitant to go WOT with the O2 not reading properly. And I'm certainly not going to spray until I see good numbers. Timing looks normal.

J.E.T.
'97 Red GTP

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[imported_GraFFix]

wow..thats sounds almost identical to my problem. the code is P0132 though? I was throwing a P0131 which is a lean fuel code.

I believe a leaking exhaust can cause these symptoms also..the EGR isnt leaking right?

you checked the connections from the O2 with a multimeter to make sure its getting the correct power? if you had corrosion its posible it went deper into the harness then you think.

I had ths same LT and ST's when I had my problem..as soon as the car gets done with the cold start cycle the ST will start rising untill it gets pegged at 20.4 then the car will start to act up..or as for me, surge and die.

An over touqed O2's sensor can go bad also...not sure how tight you made it but they do have tourqe specs to my suprise.

About the LT's I think there supposed to be at 16 untill you drive then they go down...I am still confused on this because ive heard both things...it should be at 16 or it should be at 0 going to 16. I havent gotten a answer on that yet. I do know my cars running great..my LT's are at 16 and go down when i drive my ST's stay low unless im on the gas...

Definatly sounds like a O2 problem just as mine...the PCM is trying to compensate for something. thats the reason the ST's are going up. If you have an autotap hook it up..start the car and watch the O2, LT and ST's I can almost guarantee once the O2's hit 14.7 the ST's will begin to rise and wont stop untill 20.4...then the car will run like crap.

Hope this helps some...and good luck

 

[98 TGP TOY]

Though I cant actually help you, Ive heard that the Bosch O2 sensors are horrible. Just a thought.

 

[Jamie231]

Sounds like a vaccum leak... <_< Hook up the atap and get a can of carb cleaner. spary around suspect vaccum leaks and pay close attention to the ST and LT fuel trims. If you find the right spot the fuel trim should start leveling out. pm me or call me. maybe you could come over sat and i will try to help you out.

 

[sr71_rgl]

Originally posted by Jamie231@Apr 29 2004, 01:23 AM
Sounds like a vaccum leak... <_< Hook up the atap and get a can of carb cleaner. spary around suspect vaccum leaks and pay close attention to the ST and LT fuel trims. If you find the right spot the fuel trim should start leveling out. pm me or call me. maybe you could come over sat and i will try to help you out.

I agree. It seems JET has definitly done everything but pull the SC off and inspect the gaskets....and rightfully so. Always do the easy stuff 1st. Your ltfts should bounce between +5 and -5 and sft should be at or near 0. These are ideal numbers and anything close to them is acceptable. Don't worry about the O2 sensor's reading at WOT. The pcm doesnt even use it then and is pretty useless when tuning. When tuning for WOT both ltfs and sfts will stay at a fixed value (won't change) but are based on an average of the last few ltft readings just before the pedal hits the floor. Ive read that ltfts should be in the neg for proper WOT function. Spray the carb cleaner like the guy above me mentioned and see if your rpms climb. If they do.....SC gasket leak. Hths.

 

[98 TGP TOY]

Don't worry about the O2 sensor's reading at WOT. The pcm doesnt even use it then and is pretty useless when tuning.

Are you sure? Ive always understood the the pcm to take info from the O2s during WOT. Where else would it get its info from? The ltft are only read at cruise and idle, thats why they are fixed at WOT. I know the O2s aren't extremely accurate, but I always heard it takes those readings for WOT.

 

[imported_Ron Vogel]

Originally posted by 98 gtp toy@Apr 29 2004, 01:53 PM

Don't worry about the O2 sensor's reading at WOT. The pcm doesnt even use it then and is pretty useless when tuning.

Are you sure? Ive always understood the the pcm to take info from the O2s during WOT. Where else would it get its info from? The ltft are only read at cruise and idle, thats why they are fixed at WOT. I know the O2s aren't extremely accurate, but I always heard it takes those readings for WOT.

It reads from the MAF during PE mode. The reasoning is that changes can be more rapidly read by the MAF over the O2.