LTFT airmass vs. Cell

[bbrooks98]

I'm looking for a better understanding of how this table works?I assume it's a map of what Kam cells to reference vs different Airflow points? What I've noticed running a 2013 roush file vs a standard 2011 GT file is that on the roush file during WOT i don't get long term trims carrying over from other part throttle areas. With the stock GT Kam vs airmass cell tables i'm getting some long term trims fighting against my STFTs while going WOT. I'm hesitant to just copy and paste one to the other without a better understanding, that and doing a copy the values don't match enough to show the same in a compare. Anyone messed with this?

KAM vs cell.jpg roush Kam vs cell.jpg

[Thatwhite5.0]

I'm hesitant to just copy and paste one to the other without a better understanding, that and doing a copy the values don't match enough to show the same in a compare. Anyone messed with this?

KAM vs cell.jpg roush Kam vs cell.jpg

I've had two different strategies before.. Didn't notice anything major but my LTFT are turned off either way. Start with a small increase or decrease.

twostrategies.JPG

[bbrooks98]

I've had two different strategies before.. Didn't notice anything major but my LTFT are turned off either way. Start with a small increase or decrease.

twostrategies.JPG

I'm pretty sure the 0 through 5 strategy with 20 up top makes it not use learned LTFTs at WOT, at least that's what i've noticed on one car vs the other. I guess i'll toss it in and confirm.

[murfie]

Im going to show you how your LTFT get effected by modifying your MAF curve. One is a stock MAF curve the other is multiplied by 1.45 for a large diameter CAI.

Pay attention to the period the cells now cover. Of course the MAF sensor would be reporting different periods, but as we all know the actual airflow values will not be that much different(so adjusting the KAM cells is not all that important). That said, you could not be even hitting a cell as much as you could be, or have a cell covering a large portion of the curve that may effect different RPM ranges that wouldn't see the same airflow values the average was derived from. You may want to adjust your cell vs air mass values to spread the coverage of memory out more appropriately for your intake.

STOCK LTFT KAM CELLS.PNG

CAI LTFT KAM CELL.PNG

[bbrooks98]

Im going to show you how your LTFT get effected by modifying your MAF curve. One is a stock MAF curve the other is multiplied by 1.45 for a large diameter CAI.

Pay attention to the period the cells now cover. Of course the MAF sensor would be reporting different periods, but as we all know the actual airflow values will not be that much different(so adjusting the KAM cells is not all that important). That said, you could not be even hitting a cell as much as you could be, or have a cell covering a large portion of the curve that may effect different RPM ranges that wouldn't see the same airflow values the average was derived from. You may want to adjust your cell vs air mass values to spread the coverage of memory out more appropriately for your intake.

STOCK LTFT KAM CELLS.PNG

CAI LTFT KAM CELL.PNG

Thanks Murfie, That gives me a much better understanding and I can see why how it would get part throttle values with the smaller kam values. I'll have to play with it. It seems like roush figured it out already though for a boosted car.

[superman07]

Well, that’s pretty cool shit. Thanks.

[superman07]

What’s a good rule of thumb to find the upper bound at which one should place the last point, or in which areas of airmass points should be placed for the best corrections or drivability?