Question about 2000 Subaru Legacy

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High idle For years I've experienced a sporatic and widely variable (i.e. 750-1700RPM) idle when the engine is warm. Many mechanics have tried to ID the source of the problem. Usually they say that the throttle body is dirty and needs cleanings (which I've done probably 3-4 times in the past 6 years, with no improvement. About 1 year ago, a mechanic (not the dealer-they could never fix the problem) discovered that the setting on the ICM / senor was WAY off. He adjusted it and the car ran great until...1 year later, when the same problem started again. I'll feel the car (2000 Legacy GT wagon) tugging at me at a stop light, shift the car to neutral and watch the idle fluctuate between 600-1700, with occasionaly missing. Sometimes shifting the car back to drive will almost cause it to die. One other recent development is that the temp gauge will sometimes read high during these events, although once the cooling fan kicks on, the temp will moderate. No apparent loss of coolant. Car has about 96,000 miles. Any ideas? Thanks....

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I have the same exact problem, but with idling roughly between 700 and sometimes upwards of 2000+ RPM.  I don't have the problem you do as far as the engine heat goes, but I definitely feel the tug, hear the engine sounding bogged down at stops, and when in neutral, finding it idling extremely high.  My check engine light had come on just this past month (with this problem occuring for a little over a year now), and it turns out I have a bad Throttle Positioning Sensor, which my mechanic says can cause the high idling.  I'm replacing the sensor this weekend with a dealer part, which I got for $102, so I'll post again once it's done to let you know if that fixed the problem or not.
Hope this helps,
Dan e-mail:

Posted on Oct 07, 2008


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