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Q: High idling, engine misfiring, car jumps at high RPMs

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The car has a mileage close to 140,000 miles. It has idling issues. The car has no starting problems but it would start idling high. When I'm driving, the engine would misfire as well. The car would begin jumping when the RPM increases to around 2800. After having the codes read, the error codes that appeared indicated multiple cylinder misfiring. Up to now, I only had the spark plugs replaced, which didn't help. I was wondering what I should replace to improve the performance of my car. What do you suggest?

A: Hey there thanks for writing in about your ...

Hey there thanks for writing in about your 2002 Hyundai Elantra GT. The high idle is likely a bad idle air control motor (or air leak in the intake system). The misfire also may be caused by the factory spark plug gap being too great (.045"). Gap your plugs to .032" instead. To have this checked, have a qualified mechanic inspect the high idling and misfiring problems in order to have this correctly repaired and addressed.

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