I'm going to be tuning a couple of cars on the dyno saturday and was just wondering how much of a change to the PE vs. RPM table is going to be required to change AFR on the wideband...say .25:1. Basically what kind of change would be required to go from 12.75:1 to 12.50: 1.
Anybody that's done this....I'd appreciate your experiences with this!

 

It varies from car to car, but a general rule of thumb is 10 percent PEvsRPM will richen the car about 1 AFR point (ie 13:1 to 12:1).
Quick way to tell what you need- do two baseline runs - the second will be higher and slightly leaner due to the carbon and junk blowing out. Shoot for 12.5-13:1 on a warmed up engine- the more heat soaked the engine gets the leaner it runs, so stay consistant with you changes.

Hope this helps, if you're near Virginia I tune at Woodbridge Dynotech.
-Christian
www.carprogrammer.com

 

Thanks Christian, worked almost perfect!