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Q: Rough idle and flickering lights.

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What is causing my car to run rough while in idle and my lights are flickering. Any suggestions? It is a 5 speed with quite a bit of miles.

This may be related to a dirty or failing idle air control valve. The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. This valve is controlled by the vehicle’s computer which will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed. The lower idle may also cause the lights to dim in the event that the battery may be weak. As the RPM’s dip, the production of the alternator dos as well, causing the charging amperage to the battery to drop. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your idle air control valve.

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