Whenever I come to the stop while in the "drive" position at a red light, for example, it sounds like my car is about to stall out. The RMP gauge bounces around 1. It's pretty loud. It makes my car shake and bounce. I have no clue why. I just got my oil changed but that did not help anything. Advice and potential cost?
My car has 270000 miles.
My car has an automatic transmission.
This is a common symptom of a misfire or potentially a faulty idle air control valve which when faulty, can cause the misfire to happen due to an improper air/fuel mixture being supplied to the engine. The idle air control valve is located on or near your intake manifold that monitors the air intake as it is mixed with fuel prior to being injected into the engine. 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. However, when the engine RPM drops below the normal range of 800 RPM (for most cars), it is more than likely that you are dealing with an IAC valve problem. In cases where this valve is clogged or is nearing its replacement age, your vehicle will stall instead of idling after the release of the throttle. I would recommend having an expert from YourMechanic come to your home to replace your idle air control valve.
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