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Q: Car dies at idle

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when driving at 35 to 40 mph u can feel a rumble from the car when this first start it at a redlight etc etc engine cuts off when in park or nutruel its starts up fine but when goin into gear it engine cuts off but i study this car while driving it when im doin any mph i have to give some gas to down shift a gear to go back to normal drive or in third gear im wondering if is the speed senser

My car has 124000 miles.
My car has an automatic transmission.

This may be a result of 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. Since this valve is controlled by the vehicle’s computer, it 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 with the help of the idle air control valve making the transition from a higher RPM back down to idle speed. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your idle air control valve.

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