Yesterday I removed my air pump relay. Theorically belts should run with less resistance so this action maybe has supposed some benefits in performance terms. Am I wrong?
The first thing I've noticed is that my car idles at lower rpm. Before removing this relay I was idling at almost 1100, now it's about 950 but maybe it's not as stable as it used to be.
The second thing is that my air fuel meter (not wideband) is now in the rich zone at idle. But no backfiring, just idling perfect. Can this be because the ECU is still "learning" the new parameters??

 

The stock ECU doesn't really learn. Without the extra air provided by the airpump, the car will run rich at idle which will cause a slightly less stable idle. To compensate, people typically need to raise the idle up to around 1000-1100 rpms for the idle to be steady with stock based ECU's and no airpump.

 

Doesnt the air pump only run at idle and below something like 2000 rpm? At any rate, it certainly isnt running during any kind of hard pulls and wont effect performance.