Bosephous

Alright I sure hope somebody on here can help me. My 2000 M6 T/A stock LS1 (Diablosport tuned) shows great fuel trims while driving but upon returning to idle in closed loop the long term fuel trims drop out to -10.94 on both banks exact same readings. bump the throttle an they jump to -8's to -7's and right back to the -10.94. its in the proper trim cell 19. IAC counter is 10ish to 14ish throttle position 0% an tps voltage is .4531V. Short terms are -6 to-9...already pulled the tune same readings, changed plugs, front O2's, cleaned MAF, warrantied the TPS cause I could, cleaned all the carbon out of the TB and the IAC, MAP is reading the correct vacuum, IAT sensor seems to be reading accurately will recheck tom and fuel pressure checked out good also didn't leak down with key off. possibly forgetting other specs Ive checked so somebody please give me some ideas for why it would be cutting 10% fuel at idle or what could cause a false rich condition or even possibly if its normal to see these readings which ive checked w/ Diablosport dataviewer and 2 other scan tools and they all show the same

AdsoYo

iTrader: (1)

sounds like they tuned idle rich or didn't tune it at all and the PCM is adjusting.

Bosephous

Its not in the tune it does the same when I flash it back to stock...Im almost certain its directly related to the IAT now and Im pretty sure its heat soak...noticed if I prop the airbox open IA temps drop 30* or more and LTFT's go to around -1% almost instantly then I closed the lid IA temps climb right back up along w/ the LTFT's dropping to -10 again...Im going to wrap my upper radiator hose this weekend and retest...the only thing I can think is the LTFT's arent actually showing rich theyre just showing the PCM is pulling that much fuel due to the hot intake air an thats why the STFT's are still showing good trims no matter what...I know it SHOULDNT work that way but Ive seen crazier things happen

jimmyblue

iTrader: (11)

Try making your fans run full time low and see if that
helps IAT fidelity any. If not, consider relocating IAT
to some place where it matches real outside air temps.

Bosephous

Great idea on the fans Ill try that also! Ill post up results after I get time to play with it. Thanks again for the fast responses. Id been chasin my tail for about a week tryin to find what was throwin the LT's off even graphing the data log didn't show which direction to go. Opening the airbox lid was pure luck lol its probably been like this for years until I looked for why it went rich I usually just watch the O2 volts and ST's.

Bosephous

I didn't leave this thread open sorry if anyone thought that I just hadn't fiddled with the T/A much and when I did it just aggravated me so Id leave it alone again for a while until...The RPMs would hang around 1k on the way back to idle Id been there b4 so I ran out immediately and bought a new EGR tube o-ring for the intake BAM fuel trims have dropped back to -2 at idle case closed hope this helps someone else!!!

2xLS1

iTrader: (25)

Air leaking past an EGR seal at the intake manifold would drive the trims + not -.

joecar

+1 I agree with 2xLS1...

you have not solved the problem(s) yet.

Bosephous

Sorry got locked out of my account and email -8/-10 at idle is normal I was finally able to confirm on the only other T/A around here I even went as far as having Lewis Eaton write me a new tune... but as of last week my advance auto tps failed again for the 3rd time this time I got a Standard from Fishers auto parts which they listed 2 one for auto one for M6 idk what the difference is but the new M6 listed tps fixed all the issues I was having... this is also the only parts store I've seen list 2 different tps's