Issue tuning VVE in SD.

[TAPyvehc93]

STFT SD Tuning Part Throttle.hptHey guys. I'm working on getting my VVE tables dialed in on my turbo 5.3 Sierra. I'v got it in open loop and I'm using a wideband in the down pipe to get my error. I got most of the part throttle areas dialed in within 5% which I am comfortable with because it seems I start chasing my tail trying to get it closer to 1%. I will be leaving LTFT's off and not using the MAF. The issue I am running into now is trying to tune the boost areas of the VVE table. I've been doing small pulls on the street to hit the low rpm/low boost areas and planned on working my way up in rpm and boost. When I transfer my percentage error over to the VE table and hit calculate coefficients is seems to totally change the changes I have made and it basically smooth's out the whole area removing any texture I have created. Its also creating this weird dip in the 3400rpm/90kpa range. I've done a couple pulls and made some changes to the area but its still hitting 10.0 on the wideband and it doesn't seem to be getting better. Like I said, when I make changes to that area of the VVE table and I get it looking good, as soon as I hit calculate coefficients it seems to go back to looking how it was before but with a little less fuel in the whole area. Any idea why this may be? Maybe its just going to take a lot of time? Just not sure why hitting calculate coefficients is creating this weird dip and ridge in this area of my VVE table because this is not happening in the part throttle areas.

[ZincGT]

Why not use a 2 bar OS and just use a normal VE table vs VVE?

[jjs]

My guess would that it has something to do with PE and Coefficient tables making adjustments.

[TAPyvehc93]

Why not use a 2 bar OS and just use a normal VE table vs VVE?

Unfortunately it's not available for my PCM unless I would.

[TCSS07]

if you open the vve tables on the left side of the table click on the map kpa axis you can change the table to read higher map up to 210 and 315 to make it easier to change fueling in boosted areas otherwise youll be raping the vve table which isnt good but personally i haven't dabbled in the vve tables really so i dont know if itll work but it shows higher map reading allowed for the vve

[TAPyvehc93]

if you open the vve tables on the left side of the table click on the map kpa axis you can change the table to read higher map up to 210 and 315 to make it easier to change fueling in boosted areas otherwise youll be raping the vve table which isnt good but personally i haven't dabbled in the vve tables really so i dont know if itll work but it shows higher map reading allowed for the vve

I have already done that but thank you though.

[TCSS07]

all good figure id mention it if you didnt know but yeah i haven't really messed around with the vve charts since i use maf for upper end/wot fueling, sorry hopefully someone else can chime in because im curious myself but if i had to guess it probably has something to do with the internal coding for using the coefficients but dont quote me on that

[TAPyvehc93]

Anyone? I still cant get this part of the VVE dialed in. Could this have something to do with the zone boundaries?

[lukearmstrong1990]

got a log or 2

[TAPyvehc93]

I do not but if you open up my tune, go ahead and just manually drag some cells up in the boosted areas of the map and drag a few cells up in the part throttle areas and then calculate coefficients and see what happens.

[OneTwo]

VVE is calculation based. It is basically using the coefficients to create a polynomial calculation for various places on the chart based on which zone you are in. It won't hold any specific values constant, it just does a curve fit. You cannot get exact values in one area and then make changes anywhere or it will recalculate trying to figure out the best compromise. It is not a true SD system, just a virtualized version of one using calculations to arrive at values for each rpm/map combination.