Sasha

I didn't get a chance to search the archives on this and, therefore, apolgoize if it brings up an "old" topic...

My question is for those of you who dug into our cars really deep (i.e. drilling the hole for the adjustment screw on the MAF). There are two MAF adjustments - a toothed wheel under the plustic cover on top of the MAF and a alen adjustment screw on the side. I "kinda" can guess what are those for (by observing the idle of the car while "adjusting" them) but do not have a strong understanding/procedure for adjustment. I know that a shop I tried to smog the car, adjusted them to pass smog. Now, since I got new emissions system (Cat and O2 sensor) I think I should adjust those back to factory settings.

Can anybody shed some light on this?

Thanks.

MHT

if they played with the spring tension under the black cover, unless they marked it before they started moving things, there is no way to put it back where it came from. The sensors are calibrated when they are made and not supposed to be "adjusted". The allen bolt, bypass, is the air-fuel mixture adjustment for the car, any adjustment wil have the greatest effect at idle, In order to adjust it correctly you need access to an emissions analyzer. Set the mixture to .8%CO, measured before the cat. with the O2 sensor disconnected. Before you adjust the mixture, set the base idle speed to approx. 800 rpm, using the bypass screw on the throttle body.

SoCal Driver

It's not a MAF. Having a baffle or door and not a heated element makes it an air flow sensor -- AFS.

You don't adjust the spring. You can relocate the wipers on the carbon resistor by moving the whole sub assembly down a hair. You are going to play hell getting this back to factory with out a test bench.

The screw on the AFS only adjusts the idle mixture. Again a test bench item.

You have to jumper B to C on the test plug to adjust the idle on the 85.5 and later 944's. The idle adjustment is on the throttle body.

Mark Lue

The allen screw only adjust the mixture at idle ! The PO adjusted the allen screw on my car which I had to put back to pass the smog test.

Screw the allen screw all the way in (clockwise) then back it out 7.5 to 8 turns (counter clockwise) this will put you in the ball park. I've done this on another friends car and it runs great and is still passing the smog test.