trouble getting VE just right

[kwiktsi]

Ok, I have spent a lot of time logging and tuning on my VE and it seems dead on while cruising and such (-6% or so) and my WOT pulls are good when I first reflash/zero fuel trims. But, as I drive, my 105kpa fuel trims start going -5 to -6 throughout the rpm's when I go WOT causing my WOT AFR to go leaner the more I drive. Why would it pull fuel at WOT like that? I thought it would zero out when it hits PE. Where do I look for fine tuning here? Do I just add to the 105kpa range of the VE?

Thanks in advance!
Joe
edit- I guess this would help- the car is an 05 GTO with an APS twin turbo setup and alky injection.

[Russ K]

The LS2's need to have the LTFT's very close to 0. If the LTFT's are negative at part throttle, they will be negative at WOT. The opposite will happen if the LTFT's are positive at part throttle. Just redo the Maf table.

Russ Kemp

[5_Liter_Eater]

The LS2's need to have the LTFT's very close to 0. If the LTFT's are negative at part throttle, they will be negative at WOT.
Russ Kemp

WHAT?!? This is the first I've heard of this. Can anyone confirm?

[kwiktsi]

Same here, if anyone can verify, it would be great to know .

For the time being, I just gave up and cheated and disabled the LTFT's until I can get things better. The STFT's are ~-8 at the lowest and it at least zeros out when I go WOT, so it isn't skewing my WOT fueling at least. Last thing I want to do is blow this thing up due to a WOT fueling change like that!! Maybe after a few more days of just tuning off the STFT's, I'll be able to re enable the LTFT's and have better results.

I have a feeling I am going to have to go 2 bar SD- trying to dial in a VE with a one bar map and a twin turbo setup running 16 psi isn't easy lol, but I am trying to hold on to the MAF as long as I can (old habits...)
Joe

[5_Liter_Eater]

OK, I asked Chris about this because I could not believe that negative trims would take fuel away from PE. Here's what he said:

"Negative LTFT's are not carried into enrichment, although the ECM will still report the negative LTFT value to the scanner."

[carneb]

OK, I asked Chris about this because I could not believe that negative trims would take fuel away from PE. Here's what he said:

"Negative LTFT's are not carried into enrichment, although the ECM will still report the negative LTFT value to the scanner."

That's very interesting. I had the same problem with my car and no matter how much I trimmed the MAF table I still had -ve LTFT under PE. I ended up richening me commanded PE to compensate. I have to pull out a narrow band to install my wideband so can't run closed loop AND check the actual AFR at the same time to see what is happening.

[kwiktsi]

That's good to know, I thought it was carrying over. Glad to hear it doesn't!!!
Joe