well i have the bac running decently. i set it to idle at 900 rpms which it does pretty close (bout 880).
my problem is that it tries to open up to often and the idle goes crazy lean (close to 21AFRs) it stumbles and after a few seconds it either recovers or stalls. then a few seconds later it repeats.
any ideas?

 

If it's leaning out your fuel maps are not properly calibrated. Lean mixtures will cause the idle to hunt. The BAC and it's setup doesn't sound like the problem.

 

but the problem is the idle would be fine round 12.5 afr.
all of a sudden ill hear the BAC wake up and turn on for no apparent reason (i have no ac,ps, and it happens during the day time as well) then the idle goes lean. once the bac shuts off or goes to normal duty cycle the idle is great again.

 

When the BAC comes on it's trying to increase or decrease the revs or slightly changing the load to an area that is lean.

If you don't need the BAC just unplug it.

 

i wanna keep it since i use it for cold starts. what controls how much it opens when it does open?