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Q: Audi A3 Quattro Misfires while idling

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When my car idles from 6 to 16 seconds it starts to misfire on all the cylinders. The fault code from what I can remember says it miss fires on 5 cylinders. I fixed the problem by revving up the engine. But if I let it idle it will miss fire again. I brought it to the repair shop and they said it might be caused from contaminated fuel. I have put new fuel in the car 4 or 5 times now, and they replaced the fuel filter. But it didn’t help. Do you have any ideas or suggestions?

A: Hello. If the misfire is only on that cylin...

Hello. If the misfire is only on that cylinder, then it may have a bad spark plug or ignition coil. The coils are a common failure on this vehicle.

If the misfire is on multiple cylinders, then the issue may be due to the timing belt being worn. I usually do a cylinder balance test to see which one is causing the issue. I also check the codes to see if the misfire is confined to one cylinder. If the coil and spark plug are fine, then a compression test will need to be done to see if there are any problems with the internal parts of the engine. If you want to have this done, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose the misfiring problem and perform the appropriate adjustments/repairs.

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