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!tom · Posted: Mon May 28, 2012 1:33 pm Post subject: Does the exhaust affect the idle?

I just finished doing a bunch of work to my car (clutch, motor mounts, fuel lines, exhaust).

In doing so, I put a new-to-me exhaust that I bought from another forum member that he had custom made himself.

It's a 2.5/2.25" system (2.5" before the resonator; 2.25" after). It's pretty loud, and it seems to have a lot more get up and go above 4K RPM than the piece of rust that fell off.

I also pulled off the EGR at the same time.

My idle speed is quite a bit higher now. It's entirely possible I have a vacuum leak or two, but I'm wondering why my idle speed is so much higher now than it was before.

I wouldn't expect the new exhaust to make any difference at idle.

Might it contribute to the high idle?
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78 924 NA
5-lug

leadfoot · Posted: Mon May 28, 2012 3:13 pm Post subject:

Yep 2.5" systems are loud, also dependent on muffler design too, sounds like you have freed up some restrictions allowing the engine to breath more and therefore drawing more air through the metering unit therefore applying more fuel... Etc etc,
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...