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Q: Car idles rough when in gear

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My car idles rough when I put it into gear, and it sounds like it is about to die, especially when not fully warmed up. Turning the AC on makes it worse, and when I come to a stop.

A: Hello. If the idle is that low, then it can...

Hello. If the idle is that low, then it can be caused by a number of things. Most of the time it is caused by a vacuum leak or a dirty throttle body. The throttle body being the most common. I typically clean the throttle body first to see if it clears it up. If it does, then the problem is solved. If not then the issue may be from dirty fuel injectors or it may need a tune up. If you need to have this diagnosed, consider YourMechanic, as a certified mechanic can come to your home or office to locate the cause of the rough idle and make the necessary fixes.

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