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High Idle at startup

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I have a 1994 GS300 with 144K miles. At startup on cold engine it revs up to 1800. After a few minutes it drops to 1000. At normal temperature and in drive it idles at a very steady 800. Shouldn't it be idling at about 650 at startup and in drive?  It never used to do this about a few weeks ago. Your help to diagnose the problem will be much appreciated.Thanks


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Hi Randolph....welcome to the Forum

On start-up the idle should be increased to around 1200-1300 rpm (raised idle) to speed up the engine/catalytic converter warm-up process.

Should last for around a couple of minutes maximum.

Something may be sticking in the idle control circuit if its that high...carbon build-up?

Keep us updated on what you find.

Cheers   Trevor

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Hi Trevor,

I took my 1994 GS300 to the shop. The mechanic told me that the Idle Air Control valve needs to be replaced or cleaned. It's quite normal for it to idle high at start up on a cold engine and not to worry about it.  However, if it bothers me then I can take it back and have it cleaned or replaced. It will not damaged the engine by running high at start up. So I'll leave it as is for now. Thanks for your input.


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