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Idle Control System higher than expected


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rsorrent
New User

Dec 18, 2008, 6:06 AM

Post #1 of 2 (1717 views)
Idle Control System higher than expected Sign In

I have a 1999 Mazda Miata 1.8 engine with a JR Supercharger and PowerCard. I am getting a P0507 code with my CEL on, which reads Idle Control System higher than expected. I don't know what to do about this and no one else seems to know either. The CEL came on right after I had the rear O2 sensor replaced. I have noticed for awhile is that the idle stays high until the engine warms up completely, which takes about 20 or 25 minutes. This has been going on for the last few months, but again, I don't know if this has anything to do with it. Please advise.

Dick and Saph 10 AE


Loren Champlain Sr
Veteran / Moderator
Loren Champlain Sr profile image

Dec 18, 2008, 2:49 PM

Post #2 of 2 (1711 views)
Re: Idle Control System higher than expected Sign In

The rear (or downstream) O2 sensor only monitors catalyst efficiency and won't affect the way the engine runs. It will, however, cause a CEL and an emission failure, but that's besides the point. It sounds as if the engine is taking too long to reach temperature. Could be a faulty thermostat that is not closing, completely. Or...if the engine IS reaching temp, could be a faulty CTS or connection. The computer relies on the CTS info for fuel delivery. If the CTS is falsely telling the computer that the engine is cold, it will run fast and rich. The rich mixture will take a heavy burden on the engine, O2 sensors, and the cat.
Loren
SW Washington






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