Hey,

so I noticed that most say to tune idle for maximum vacuum. I am curious what A/F ratio you guys are getting with these settings? I'm more of an EFI tuner and all the EFI cars I have had idle at 14.6:1 or right around there. I noticed that my charger when tuned for max vacuum is reading 15.2 - 15.6:1. Is it OK to be a little lean at idle?

Mine also shows high a/f ratio when set at highest vacuum. It typicaly even shows higher when the engine is still cold (17-18) I was told by a member on this site to simply set it for the best idle quality and that is what I ended up doing, with no bad side-effects so far. (I would think the biggest advantage with the most vacuum would be with power brakes, I am running manual dics)

A 4-speed car could idle with a leaner mixture as long as it does not heat up. An auto car needs to be tuned in D to the highest vacuum reading (which will be richer than in N) and then when it is put back into N, then you might have to live with the richer N reading.