After looking at the Tunercat help file, it looks like I would use the Volumetric Efficiency Vs. RPM Vs. Load and the Volumetric Efficiency Vs. RPM Vs. Load (Ext.) tables to adjust the air-fuel ratio that is used when the car is not seeing WOT. So, am I supposed to blindly increase or decrease the VE values? Or is there some sort of formula or spreadsheet out there that can help me guess, such as the WOT AFR formula that the Tunercat help file gives?

 

Although you can adjust part throttle fueling with the ve tables, you can't change the fact that at part throttle the PCM is going to shoot for ~14.7:1 a/f ratio as long as you're using a closed loop strategy.

 

what is the best way to change the A/F ratio the computer looks for with tunercat?

 

Unless you run Speed Density mode changing the VE tables arnt going to help you. If you run in SD mode you can use a program called VE Master to make changes for you based on Datamaster logs.

 

At part throttle? You can't.

 

The PCM will always try to run @ 14.7:1, unless in WOT. In your car, I would try by adjusting the MAF tables.

What does your fuel trim look like? How bad, etc...

Oh yeah, be sure to check out the link in my sig since you're local