Hello,

My 2004 XC70 is having fluctuating idle speed (500-1200)/stalling at idle problems. It runs great except at idle.

I have the following codes

P2188 -system too rich
261A - long term trim
262A - long term trim

The throttle body is clean and smoke test showed no vacuum leaks. The spark plugs, coils, filters, etc are new or fairly new.
I checked the signal from the MAF which showed fairly steady 1.58-1.6v at idle (cold), 1.16-1.18v idle (warm). If I accelerate slowly the reading is goes to 2.4v at 2000rpm, 3.2v at 3000rpm. If I accelerate quickly the voltage goes to 0 when I open the throttle, then recovers to shown readings. The car accelerates strongly, no hesitation.

Is this normal for the MAF?

Oddly enough, if I unplug the MAF, I get CEL and code for the MAF but the car idles perfectly smooth, no stalls, runs great. When I plug it back in, it goes back to fluctuating and stalling.

Ideas? Thanks, Jim