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Q: Rough idle at 500 rpms

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Replaced #7 coil and spark plug after plugging in computer. Did not fix. Engine runs smooth while driving. 105,000 miles

My car has 105000 miles.
My car has an automatic transmission.

The first thing to do is a cylinder balance test to see if all cylinders pass this test and relative compression test. If a cylinder fails either test, then follow the pinpoint test and see if the injector is getting signal using a noid light. Check the injector for proper resistance. Swap the #7 injector with another cylinder injector or with a known good one and see if this fixes the problem. If you swapped to another cylinder, then the code will move from #7 to the cylinder you swapped the injector with. Replace the injector and clean all injectors using a pressure type injector cleaner. If you want to have this inspected in person, a technician from YourMechanic can come to your home or office to diagnose your car’s rough idling issue.

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