RRE 1G MAS Adjustment/Hacking  Instructions 


Location of the MAS adjustment screw. It is a threaded plug buried under the blob of silicone in the hole

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Use a screwdriver to dig out the silicone.

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Here you can see how the screw is threaded into the MAS more. This way blocks off a portion of the un-measured air flow through the MAS. The car will run richer this way

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Here the screw is backed out flush. It allows more air through the MAS that is un-measured. The car will run leaner this way.

Do not remove the main upper square honeycomb section. This is needed to straighten out the air flow before it enters the main measuring chamber.

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The lower oval shape screen is the lower honeycomb. It may be removed by prying up the two retaining tabs and gently pushing it out. Save it in a safe place, you may want to put it back in some day.

GVR4s come stock with now honeycomb screen over the lower section.

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For cars with some form of electronic adjustment of the air flow signal (AFC), you can further hack out the obstructions of the lower bypass chamber. We use an air powered hack saw to cut out the channels. Then smooth the chamber sides with a porting tool.

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On some severe applications, the entire lower chamber can be hacked away and ported smooth for maximum air flow. This should be approached slowly and one step at a time.

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