How do i tune my Jeep VE using LTFT's?

[bluegoat06]

I see there are 2 tables, VE bank 1 and VE bank 2, looking at posts from 06300csrt8, I see he mentions using this tables to tune VE, and he makes both the same ?, however in my 2013 Jeep Calibration, the parameter Engine/Airflow/General/VE Bank 2 Disabled is set to yes from the factory, so i'm assuming i'll have to make changes only to VE Bank 1 or both tables ?

ve_bank2_disable by SilverFJ RSM, on Flickr

Also, the VE bank tables reference RPM and ratio ? what's ratio ? and from the PID list in the VCM scanner 2.25, how do I reference this ratio ?
I want to create a histo to log rpm vs ratio vs LTFT, then use the LTFT error% to add/remove from the VE Bank 1 table.
i guess the math is still the same, -5% LTFT means i need to multiply by .95 to remove that extra 5% richness (as a ballpark, normally i add/remove half as to not over do the fueling)

VE_Bank_1 by SilverFJ RSM, on Flickr

[06300CSRT8]

you are on the right path...as good practice I always copy the same VE table over to VE Bank 1 and 2, even if the VE Disable is set to Yes or No. I have changed mine from the factory setting of No to Yes, which should disable the second VE Bank and run all fueling off of Bank 1, but it didn't appear to work as I made some pretty drastic changes to VE Bank 1 and saw almost no changes to my Bank 2 LTFTs my next time out.

Ratio is pressure ratio, which is manifold pressure divided by barometric pressure. I have the PID in my 2.25 for my specific car, you should be able to hopefully find it as well. Try to add a parameter once connected to the car and type in pressure ratio to the search, see what comes up.

And yes, if you see -5% as a LTFT you would multiply that cell in the VE table by (1-.05) = .95, but as you said I usually never go over 50% of the value of the LTFT so I would do .975 instead. I also usually factor in my STFTs as well, as a lot of times they are going the opposite direction of the LTFTs and may act to reduce what you actually adjust by.

You must realize as well unless you add a custom filter, you are going to pickup deceleration fuel trims, which can be massively negative. Usually I look at the general direction of my fuel trims in a certain area, then switch the histo to either be peak positive or peak negative and use those instead for fuel tuning, and just toss out the fuel trims that look like the deceleration areas.

[bluegoat06]

Awesome thanks a lot for the explanation 06300, I found the pressure ratio PID, and will attempt to log data this afternoon with it, if that doesn't work, hopefully Scanner 2.25 will allow me to create a custom PID using manifold pressure / barometric pressure.

[bluegoat06]

The Pressure ratio pid worked like a charm, thanks one more time 06300.

[obzidian]

Are you able to disable decel fueling?

[HemitunerAJ]

The VE table is Disabled because in that application it doesn't use the VE Tables at all. In order to use ve-tables you would have to turn the ANN off, Turn the bank 2 table on then start from scratch mapping the VE. The factory uses the Artificial Network exclusively for anything with a variable cam.
Hope this helps
AJ