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Re: engine races when put in Park
There are a few things that can cause over-idling. Here a few things that come to my mind:
1. Vacuum leak. Air leaking in anywhere and not being monitored by the Mass Air Flow (MAF) sensor will lead to idling problems. This is a "big opportunity" as there are so many hoses that can develop leaks.
2. Dirty MAF or Intake Air Temp (IAT) sensors. Careful cleaning with circuit board cleaners will usually restore performance. A poorly sealed intake air filter, or air canister, will cause this problem.
3. Idle Air Control (IAC) valve. Usually can be cleaned ... sometimes a new one is required.
4. Engine Coolant Temp (ECT) sensor. If the coolant hasn't been maintained properly, these sensors will fail prematurely. Of couse, they may eventually fail anyway.
5. Throttle Position Sensor (TPS) ... rarely the cause, but it can happen.
6. The ac controls can cause an idling problem. I think the 98 is one of those years that the ac runs anytime the air controller knob is not "off". ???
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