any way to disable LTFT's at 105 kpa on an ls2?

[kwiktsi]

Like the title says, I was wondering if I can disable the LTFT's at 105kpa? I am having issues tuning my TT ls2- no matter what I do with my VE, it always seems to carry a negative LTFT into the PE and lean out after a while of driving. I will go from 11.5 AFR to 12.5+ after driving for a while. I was thinking maybe max out the min map vs. baro at 105 kpa so it never enables LTFT's there- is that right?

My VE is kicking my butt too- I will get it where I think it is perfect, then it will be way out of whack again. I am going to try to play with it "maf only" and "disable" the VE to see if I can get it any better. Ugh, this is frustrating. I think it is making it worse since I am spraying a good amount of alky- it is making everything hard to dial in .

The only other thing I can think of (and it seemed to work "decent") is to disable the LTFT's all together, but I would prefer to keep them enabled- just not at 105 kpa . Thanks!
Joe

[5_Liter_Eater]

I'm still not convinced that negative fuel trims in PE have the effect of reducing fueling. But in the mean time I would just disable the LTFTs. The STFTs will still do a good job of correcting for any airflow metering discrepencies.

[Russ K]

You need to get the LTFT's closer to 0 so they won't pull fuel when entering PE.
Get your part throttle fueling closer.

Russ Kemp

[5_Liter_Eater]

I can see where the fuel trims lock negative in PE when you enter PE from a negative LTFT cell but has anyone checked to see if this actually pulls fuel? I'm thinking it is just a "bug" that the negative trim carries over but I would be very surprised if this caused fuel to be taken out in PE mode. This would mean that if a car had a -10 LTFT, stoich of 14.68:1 and the PE was, say 1.17 (~12.5:1) then the actual AFR would end up to be ~13.8:1. The LTFT could go as low as -25 which would end up in a rediculously lean AFR.

[kwiktsi]

I don't know for sure, but it does appear that my car is running leaner (WOT in PE) the more I drive, so I would "assume" that yes, it does carry over. Also, being FI- I don't want to experiment too much to see if it indeed does keep getting leaner . It does seem that it does affect WOT PE fueling though from the logging sessions I have done with this car.

As for getting the part throttle VE closer- I have probably adjusted it a good 40-50 times and it will be pretty good for a while, then way out of whack again. I also spent hours today getting my MAF error correction to less than 2% (+ or -) and by the end of the day it was -16+ and this was with LTFT's disabled . The only things I can think of off the top of my head are 1- the IAT is heat soaking and 2- the previous owner put a 160 stat in the car and you can only turn the fans on at 196 or whatever with the LS2, so my temps will range from low 160's to ~200 degrees throughout the day- I'm sure that is affecting my fueling too. I am thinking of just putting a stock t-stat in it.

Any ideas? Thanks.
Joe