CIS Question

[jhelgesen]

Got a question on my CIS, its got issues (imagine that). When I start the car cold, it idles at about 8-900 rpm, after it warms up, it goes to 1800-2000 and stays there. Any quick suggestions of what might cause this?

Thanks!

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[Superman]

Sometimes my idle rises, during warmup, but it settles down. I think there is an Auxulliary Air Regulator, and on my car it is located approximately above the #5 cylinder head. A couple of thick hoses are attached, and probably one of those rectangular, "Bosch Fuel Injection" electrical plugs. your AAR may be staying open.

Or perhaps not opening at all, and your idle bypass screw is misadjusted to compensate. that is, to give the engine the extra air it needs during warmup. The extra air should be coming from the AAR, not the throttle body. Then, the AAR should close, giving you a good warm-engine idle around 900 rpm.

[bb]

Whar does the AAR do on the system?

Thanks
Oscar

[Paulporsche]

I think Superman is right that your idle may be set to compensate for what would be a too low idle @ cold start. Search the WUR. Usually the cold control pressure is too high which causes the mixture to be too lean until the engine warms up. You can adjust this back into the correct range.

Also try searching the AAR. It works to help the WUR in keeping the revs high during a warmup, gradually allowing the revs to fall to the correct point when warm.