General Fuel Trim Question..

[saxmanbrad]

Hey guys, tried searching for general info about this, but decided to ask as well. I am running a Hypertech tune with a Cobb SRI and RPMC inlet, I'm not too sure what kind of fuel trims I should be looking for..Also, what is the difference between the two? (i.e. the difference in monitoring)...also one more question, should they different from idle all the way up to WOT? Thanks any input and I apologize for the N00B-ness of my question!

 

[Darth Vader]

The closer to 0 the better. STFT (Short Term Fuel Trim) is constantly adjusting and can be ignored unless it's stupid out of whack. LTFT (Long Term Fuel Trim) is the ECM gained experience of your car's fueling needs. This being at 0 would be ideal but, it's not abnormal to see +/-6 or so. Anything +/-10 or more is a cause for concern.

 

[b e z]

So i noticed on my ultragauge coming home that my long term reads 8.59 for the most part but also goes to 10.94 and then randomly 14.34. I have no clue what these mean but thats not close to 0 at all. While i was driving highway at 65 in 6th it was 8.59.

 

[the_caruch]

So i noticed on my ultragauge coming home that my long term reads 8.59 for the most part but also goes to 10.94 and then randomly 14.34. I have no clue what these mean but thats not close to 0 at all. While i was driving highway at 65 in 6th it was 8.59.

i'm at around +3% at 65mph and goes to +6 if i give it a little throttle to gain a few mph. The only MAF values i've touched via the standback are the idle and wot values. All cars are different, 9% cruising is fine. If it bugs you, you can modify it via AP or SB (whatever you have). More importantly is finding out your LTFT when you are WOT