88 S4, adjusted MAF.
 

So..thought Id tackle this, see whats up after putting in a new O2 sensor...since the one that came with the car was all hacked up in the wiring just above it under the car.

Pulled air filter box, snugged up the hose camp the MAF sits in (previously was entirely NOT tight, the MAF could have rattled in there). The hose to TB is however, tight.

So...had the capable 12yr old here run up to 2500rpm for a bit..all warmed up, fans working on and off.

Pulled sensor plug..yup runs differently.

Checked voltate. 7.85'ish...fat. Ya..I scrubbed off the Exxon Valdez from the bumper this morning..it runs fat.

Got the handy 3mm hex piece that goes in the end of a screwdriver, and fits nicely into the adjuster and started turning. Turned in, was fatter. So a couple thumb-finger twists at a time, and had kid read off the meter..slowwwwly came down, and im in the 4.9/5.1 range now, considering the meter doesnt sample as fast as the voltage actually changes.

Put it down to idle, held the #s nicely.

Plugged in the O2 cable, and the idle settled down instantly..doesnt stink behind the car anymore.


We shall see what a test-only smog test says tomorrow perhaps.

I thought that on the 87+ cars, there was no MAF adjustment. That adjuster is only useful on the 85-86 cars.

You may want to look into this and see what the real issue is.

Matt

Matt your correct .
On the 87 and newer cars, the MAF unit adjustment is not connected to the computer its controlled with the O2 sensor and the MAF.
If you look in the MAF plug you will see pin 6 is missing.

The only systems that can be adjusted are the LH2.2 these are found on the 85,86,86.5 cars
If the car is not running well and a new O2 has been fitted then it would be a good idea to have the MAF unit overhauled