RRE's 2G Eclipse MAS Screw Adjustment Information


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The 2G MAS calibration screw is located on the bottom of the MAS. It is buried under a blob of silicone. Use a screwdriver to dig it away.

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With the silicone out of the way you can see the slots for a screw driver.  Turn the screw out (counter clockwise) to make the car run leaner.

Turn in (clockwise) to richen.

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Looking through the MAS you can see how the screw blocks off air flow through the lower center channel. Your MAS will vary quite a bit compared to MAS of another car. They come from the factory screwed all the way in and all the way. Everywhere in between too. It means nothing other than that is what Mitsubishi did to get it with in the range that they wanted on a test bench. 

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Here you can see what it looks like with the screw all the way flush. This will allow more air through the MAS that the ECU will not see. 

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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 from the inside with a pencil eraser. Push out even and gently, they will slide out.

Here you can see the MAS with the two side honeycomb sections slid out. 

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Shown here is the lower honeycomb out. DO NOT remove the large square center honeycomb. Save the honeycombs in a safe place, you may need them later to get things right. You can remove them one at a time to get the result that you are after.

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Don't even try this with out monitoring your O2 sensor voltage. We use the Jumptronix Digital A/F Ratio Meter.

The car will run disproportionately leaner at lower air flow levels than at high air flows. This modification will allow you to lean things out some if you are running rich . What works best for full throttle may cause a lean and/or rough idle. A over lean idle will also cause the  "check engine light" to come on. Not a problem if you can live with it. 

If you have an AFC you will be able to compensate for the leaner condition at low air flows.  

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Santa Fe Springs, Ca. 90670
Tel (562) 777-1522     Fax (562) 777-1562
Last updated 1/01