ManBearPig
Well-Known Member
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I have been working with Lund to try to dial in the MAF curve on my JLT intake. I have started paying close attention to the fuel trims on the nGauge as I drive and I have noticed a trend.
If I toss the car into neutral and let it idle down while I coast down the road, the STFT shoot to about +20% and stay there until I come to a stop, then they settle down. If I am close to a stop before putting the car into neutral and stopping, the short term trims only get out of line for a few seconds before calming down.
I once wanted to see if the trims would eventually settle down while coasting and even after coasting half a mile or more they stayed elevated. Even to the point that the LTFT started climbing....they got up to 13% before I came to a stop. Once at idle, the short trims slowly pulled the long trims back down close to zero.
The trims are pretty close everywhere else. Within 5% at least.
Is it possible that the short trims stay elevated when I’m moving because there is air being forced into the airbox and the pcm has to add fuel to compensate to keep it at 1.0 lambda?
Just a theory, but it makes sense to me.
Thoughts?
If I toss the car into neutral and let it idle down while I coast down the road, the STFT shoot to about +20% and stay there until I come to a stop, then they settle down. If I am close to a stop before putting the car into neutral and stopping, the short term trims only get out of line for a few seconds before calming down.
I once wanted to see if the trims would eventually settle down while coasting and even after coasting half a mile or more they stayed elevated. Even to the point that the LTFT started climbing....they got up to 13% before I came to a stop. Once at idle, the short trims slowly pulled the long trims back down close to zero.
The trims are pretty close everywhere else. Within 5% at least.
Is it possible that the short trims stay elevated when I’m moving because there is air being forced into the airbox and the pcm has to add fuel to compensate to keep it at 1.0 lambda?
Just a theory, but it makes sense to me.
Thoughts?
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