Q: car shaking/vibrating when idle

asked by on October 10, 2016

Car shaking/vibrating slightly when idle or standing at traffic light. Initially it happened only when car was idle or it was turned on, gear was in parking mode. But now it occurs even in driving mode but only when standing at a red traffic light. It feels almost like a spark is happening inside the engine or something. Vibration can be felt in steering but more prononuced in car seat. It occurs more frequently now.

My car has 110000 miles.
My car has an automatic transmission.

Hello. This sounds like potentially a failing idle air control valve or potentially a misfire. The idle air control valve regulates the air intake into the engine as it is mixed with fuel prior to being injected into the engine. When this is not working properly, this can cause the engine to starve for fuel which can trigger the car to misfire or simply run very rough at idle or low speeds. The rough idle will cause the car to shake as you describe. I would recommend having an expert from YourMechanic come to your home to diagnose the rough idle and replace the idle control valve if necessary.

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