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Q: Skipping during idling and driving

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My Passat started running very rough and having a backfire during acceleration that seemed to come from the engine. I replaced the spark plugs and it is running much smoother but still has an occasional skip. It does seem to backfire a little at about 1500 to 2000 rpm as I'm accelerating.

When changing the plugs, I noticed what seems to be oil in no. 5 and 6. What could be causing this?

My car has 195000 miles.
My car has an automatic transmission.

Hello. Oil on the spark plugs can be an indication of a failed O-ring, worn piston, or worn valve guide. The first of which is less serious than the others, but it should be inspected sooner than later. Catching a more serious issue now may save your engine. It may be related, but don’t assume the worst just yet. When experiencing a misfire after replacing the spark plugs, the first step should always be to retrace your steps and make sure the plugs are installed correctly. Pay extra attention to the spark plug gap, which can be altered when you tightening the plugs into place. You will also want to verify that the spark plug wires are securely attached and are clean, dry, and tight. If the misfire is being caused by something else, it is likely it will show itself on a diagnostic scan, so have the vehicle scanned at your local parts store. You should verify the repair and then have the vehicle scanned if needed.

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