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My 2001 Mitsubishi Airtrek 2wd with 86000k revs at 2250rpm for 30 seconds before slowing. Will this speed harm the engine?

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Have flagged previous question for close, but did you know you can edit your question? And you should probably edit this one to add info such as when this happens etc –  Rory Alsop Aug 30 '11 at 8:06
    
Thankyou. I omitted that this is idle speed with a cold start. –  Chris Sep 5 '11 at 22:10

3 Answers 3

This is the modern equivalent of an automatic 'choke' - this is the ideal speed for the engine to rev when it first starts up to bring up the temperature, get the oil circulating etc. It isn't a high speed anyway.

Most cars do this to some degree or other. Perfectly normal.

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No. Revving to a certain level based on computer and fuel input will not harm the engine as long as that RPM is not within the 'red zone' and is within the engine's normal operating parameters.

If this behaviour is new, it may be a sign of a clogged O2 sensor, a clogged EGR port, a bad relay, or any one of a hundred other problems. You should see if your engine is throwing any codes via the OBD-2 port. You can usually 'borrow' the OBD-2 readout computer from an auto parts store cheaply or for free.

Note: I'm in the US; names for parts or policies may be different where you are.

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I did not mention that this revving is idle speed at startup from cold. Idle speed is normal when hot. Vehicle is newly purchased. Thankyou for your reply. –  Chris Sep 5 '11 at 22:03

Is this a new behaviour? Many cars (especially OBD-2, not so much earlier models) will rev to 2000 or even 2500 for 10-30 seconds on start when it's cooler out (some even do it on warm days). If it's a new behaviour, you may have a faulty Idle Air Controller. If it's always done it, I wouldn't worry about it too much since it's pretty common for newer cars to do that (wondering if maybe it's an emissions thing to help get the O2 sensor warmed up quicker?).

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Vehicle is newly purchased. The reving is at idle from cold, as you surmised. Idle from warm is normal. Thankyou for your reply. –  Chris Sep 5 '11 at 22:07

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