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Q: My truck shakes at traffic lights

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My truck shakes at traffic lights when hot. The shaking isn't that big but I can still feel it. When I stop at a traffic light my truck shakes for a while, stops, and then starts shaking again. The truck drives and runs very nicely, and I haven't had any troubles with it. I don't have any warning lights on my dashboard such as check engine. When the truck is cold it doesn't shake at all but when it gets hotter when the truck idles it shakes. I've noticed that my rpm needle isn't steady when idling it moves up and down just a little bit up and down, thank you for your help.

My car has 143000 miles.
My car has an automatic transmission.

A: Hi. The symptoms you describe could be a di...

Hi. The symptoms you describe could be a dirty or malfunctioning idle air control valve. Especially when hot, when the engine gets a leaner mixture of air and fuel, the idle air control will have a greater effect on idle and low speed running. In general, it will not set a Check Engine code either. I would recommend having a rough idling diagnostic completed by a mobile professional mechanic, such as one from YourMechanic, to inspect the problem and replace the idle air control valve if needed.

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