An acquaintance, backyard mechanic, messed with my air flow sensor setting screw. It ran okay for awhile, but now is running very rich as judged by mpg and the tailpipe black color. Mpg went from 34 mpg average to 29. He screwed it in alot beyond where the factory locked it in with some kind of RTV. He also adjusted the idle adjustment screw/locknut as the idle dropped way low. That was 4 months ago.
I looked at the manual. Says basically not to mess with it. Is there a ballpark region I can adjust the mass air flow sensor? The manual says 800 rpm for idle.
88 VW 1.8L Fox Dave