Why are my fuel trims fighting each other?

[ManBearPig]

Car has longtube headers, JLT cold air, Lund tune. If i reset the KAM, fuel trims start out really tight. Usually adding only a percent or two at idle, part throttle, and WOT.


As time goes on and the car adapts, the trims will start fighting each other. After 200 miles and 4-5 drive cycles or so I’ll see the long term trims learning pretty far off, but the short term is always right there opposite. For example this morning I saw -10 long term and +8 short term under WOT.


Car pulls very hard. Sees 31* of spark on 93 octane and peaks at 47 lb/min on the MAF. It runs very strong and doesn’t have any drivability issues.


Any ideas what would cause the PCM to adapt like this? My tuner says it’s fine but it doesn’t give me a warm fuzzy feeling.


Thanks

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[Nuked]

Air was probably cooler and denser this morning when you saw the STFT adding fuel. I wouldn't worry too much honestly, car is doing what it is supposed to.

 

[Kong76]

I thought I read as long as the two cancel each other out you are running normal.

 

[ManBearPig]

My understanding from tuning gurus is that you don’t want the short terms very far off because there are instances where the pcm can’t apply these corrections fast enough or at all. Quick transitions on the pedal can take place too fast for the short terms to correct fueling, and when the pcm is in closed loop the short term corrections aren’t being applied at all if I’m not mistaken.

Unfortunately I know only enough to be dangerous with this sort of thing but not enough to know the answers to the questions my OCD asks.

I’m not claiming the tune is off. I believe it to be pretty close considering the total trims are always very tight. Just wondering h if there is something up with the car or some environmental factor causing it to adapt like this?

Tuning expert opinions welcome.

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