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Q: Idle speed too high.

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Once the engine warms up, the engine speed some times goes to 1200 to 1500 RPM at idle. Tapping the accelerator will some times bring it back to 800 RPM. Thought the AC might have been the problem, But, I'm now convinced that may not be the problem.

My car has 133000 miles.
My car has a manual transmission.

Hi, thank for your question. If the AC is coming on but the compressor is not engaging, then it could cause a higher idle than normal. The throttle position sensor and idle control valve need to be tested with a scanner to see if the TPS is set correctly and the idle control valve is sticking open from carbon deposits. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect this idling issue for you, and make or suggest any repairs as needed.

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