Ive been chasing this problem for about a month now and i cant figure out why my LTFT are pegging at 16.4 during cruise. What I did so far is a vacuum gauge test and its holding at about 20 in/hg so a vacuum leak is not my problem. Changed fuel filter, MAP and both O2 sensors with same problem with LTFT. At idle my LTFT hangs between 0.0 and -3.2 but anytime i give it any gas it jumps right to 16.4 and stays there until i let off the gas and at WOT it locks in at 14.8. I first discovered this problem when i saw i was getting KR at freeway speeds and when i checked for LTFT they were pegged at 16.4 and not moving. Ive had all my mods listed below for a good 6 months problem free and then this problem appeared. Im beginning to think that my PCM wasnt right from the beginning and it just took the temperature to rise for me to see my KR im getting now because all the mechanicals seem to check out fine.
When i first decided to buy a pcm all i wanted to do to the car was downpipe, CAI and a 3.5 so thats what i got it tuned for. My plans changed when my uncle gave me a set of headers and with that i dropped to a 3.4. Would adding these two things through my tune this far off? Any ideas would be great!
