If you are running rich with a slightly modified DSM, a cheap and easy way to help lean things back out is with the MAS. The 2G Mass Air Flow Sensor (MAS) calibration screw is located on the bottom of the MAS.
Theres a silicone blob protecting the screw from movement. Use a screwdriver to clear away this blob.
With the blob removed. You can see the MAS screw there for adjustment. Turn the screw out (counter clockwise) to make the car run leaner. Turn in (clockwise) to richen. Note: These changes are very minor, and should not be used as fuel management. They do however, allow greater unmetered air flow by turning the screw out.
You can also remove honeycombs from your MAS. We usually don’t recommend this but if you are running so rich and cant afford an AFC, its an easy fix.
Remove the four Phillips screws that hold the plastic grate onto the face of the MAS. Once the grill is off, The honeycombs can be pushed out with a pen or Q-Tip. Push back and forth on the edges of the honeycomb in question until it just slides out. Keep these safe! You may need them in the future. We only recommend removing the bottom smaller honeycomb or sides. DO NOT remove the large center honeycomb.
More info from Hal Landry (creator of Tunerstein):
Removing any of the honeycombs alters the response curve. People have seen a very lean spot at around 4k rpms with one or more of the honeycombs removed. Removing ANY h/c’s without proper fuel control (AFC, etc) is a BAD idea. The STOCK 2g MAF has been proven to flow enough for more than 400 wheel horsepower.
What’s needed in putting a 2g MAS into a 1g?
To put a 2g MAS into a 1g Eclipse / Talon / Laser, you need to get the 2g MAS, and a 2g MAS wiring harness.
You will also need either a new air filter, or a bracket to connect your 1g air filter to your 2g MAS.
Check out our writeup here.