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Idle is loopy


slick

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I start up my car tonight, and its idling real bad, between 700 - 900 rpm. When I pull away from the stop sign and turn my wheel, it about dies, until I give it a crap load of gas. After driving around for a while and coming home, i pull into the driveway, shut it off, and check the plugs. All good, so I start it up. At first it starts real low, talking 300 rpm, then shoots up to 3000 rpm, while in park, and slowly comes back down. So i shut it off, and come back inside for a while, then decide to go out for a while. I go to start my car, and it wouldn't start. So I tried again, and it does the real low rpm thing again with the high rpm again. I'm thinking O2 sensor, but not sure.

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I can tell you FOR SURE that it is NOT your O2 Sensor. Your PCM(computer) totally disregards the O2 Sensor until the engine is in "Closed Loop", which usually takes about 3-5 minutes of SOLID driving(not idling). The O2 Sensor has to reach 600 degrees F' before it's useful.

 

The obvious thing to me is the IAC(Idle Air Control) valve. Possibly a TPS(Throttle Position Sensor) being "jumpy" and confusing the PCM. The PCM needs an accurate TPS voltage in order to determine when there is 0% throttle, and therefore idle speed.

 

I would put the IAC at the top of the suspect list though. Especially since you said the engine almost "died" when you turned the wheels. That tells me that the IAC was NOT responding to the PCM's command due to the extra load being applied.

 

One other thing, if your car has a Power Steering Pressure Switch, it could be a problem, but highly doubtful.

 

:)

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I agree with the above, however, I personally havent heard of the IAC just going bad all of a sudden, and thats why I would think TPS first, but thats just me.

 

Robby

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I don't think it's the DIS mod. but if all else fails... When mine went bad it would drive fine and intermittently try to run @ 300 RPM max no matter the throttle position. It was interesting, it sounded like it had died but I still had power steering.

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