Just as the post say's. How close do you have to tune before the computer tunes it's self.

 

If it has to pull the tune by more than 25% (+ or -)
in closed-loop operation you will set a code MAF code.
I believe that's the limit of the trims' "pull range". The
PCM only "tunes itself" in the part-throttle, closed-loop
regions.

Running that far off still leaves you with poor WOT
performance and transient-throttle behavior, maybe
worse things if you err on the lean side (on the rich
side, it's just a pig).

 

In closed loop operation with the O2 sensor hooked up your car will only correct the a/f ratio between 13.0 a/f and 16.6 a/f.

If you car strays outside the above said boundries in closed loop you will set a DTC. The car will still attempt to correct itself, but it will apply its maximum correction of 1.7 a/f points.

 

I have some logs that show +/-50 strims