So I've been searching the forum and I can't seem to find a definitive answer. I'm still learning about proper A/Fs, LTFT, and STFT on these cars so bare with me if this might be a novice question.

The other day I was logging my car with a scan tool a buddy of mine has, and I seem to be getting wacky fuel trims. My LTFT were right around -12, and my STFT were pretty good at WOT between -0.8 and 0.8, but just cruising around at highway speeds they seemed to be all over the place. I'm ranging somewhere between -6.7 and 6.3 just cruising around on the highway.. Is this normal? I will say that at WOT I am getting some great flow though @ 38lbs/min. I'm guessing I must be running super rich if my LTFT are in the -12s like that.

Anyone know if these numbers may cause any issues?

 

CAI is skewing MAF readings..

 

even if I was tuned with the CAI?

 

Your MAF is skewed by over +12% (indicated by the -12 LTFT) so in reality an indicated flow of 38 lbs/min is actually ~33.44 lbs/min. Your car is running very rich and the ECM is trying to compensate by spraying 12% less gasoline than was indicated as needed by the MAF sensor. You have an intake correct? If not someone messed with your MAF tables when they should not have. NM read your sig. Were you tuned with that intake on the car? If so you were not tuned for it. LTFT should be -1 to 0 and STFTs should be +3 to -3 on a well tuned car.

 

crap.. lol.. yeah i was tuned with the same intake, however i do have a new catless dp that i was not tuned for but i would think that the dp would lean me out if anything, although that is just a guess on my part.

crap........

 

I second that. My car ran like **** as far as daily putting around and it always smelt super rich. Took me about 5 or 6 different tune adjustments just with the MAF to get mine down, I have a 3inch CAI and my LTFT were about -9 and STFT were all over theplace going as high as +12. smoothing this out will make the car drive soooo much better as well

 

Catless DP will not cause a -12 LTFT. It is the fact that you were never tuned for that intake in the first place.

 

QFT. Gotta tune any intake out there currently.

 

He says he was tuned for it.

 

Perhaps his tuner lied...or didnt know what he was doing?

 

Ding ding ding....

 

Yes I was tuned with the same intake. The only thing different on the car is that I now have the catless dp and I no longer use my side exit exhaust. I wonder if the fact that the car was tuned in the middle of summer (90+ degrees with high humidity) would effect the trims? I would think the colder/denser air would lean me out if anything :::::shrugs::::::

hmm.. I really hope that's not the case, especially seeing as how it was tuned by trifecta.

The car has never given me an issues with drivability, CELS, or any issues in general. Not to say that doesn't mean something funny wasn't going on that the car wasn't making me aware of. Would running a slightly higher octane fuel skew my fuel trims at all? In my tank at the moment I have been running a 10:1 ratio of 93 octane and 104 octane fuel, nothing crazy. So it's probably only a couple of points increase at most, but could that have any effect?

 

That Im not denying LOL. Just saying he claims he WAS tuned for it from TF...