Q: My car is idling rough and flooding out when first starting. What could be causing this?

asked by on November 08, 2016

At first starting. It will be smoking and flooding out. Then seems to get better. Still idles rough and if put it in gear and hold the break it will die from the rough idle. Put new distributor in it and tuned it up. The check engine light is on. Took egr valve off of it and let it run then put it back on and it seemed to help but if let idle for to long it would go right back to idleing rough

My car has 245000 miles.
My car has an automatic transmission.

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. This is all controlled by the idle air control valve. When the engine RPM drops below the normal range of 750-800 RPM, this may indicate a dirty or faulty idle air control valve.

I would recommend having an expert, such as one from YourMechanic, come to your location to determine why the car is running rough and replace your idle air control valve if needed.

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