Pontiac Problems? Ask a Mechanic for Answers ASAP
Do you feel the engine misfiring when running? If so, is it more prevalent when idling or when under load (accelerating)?
Sorry for the delayed response. Does the check engine light flash at idle? Have you done a compression test or tried to isolate the missing cylinder by pulling plug wires off one at a time with the engine idling?
You are welcome. Will look forward to the results of the compression test.
It could cause the misfire code. Since #1 and #4 are paired on the same coil, it can also cause a false trigger of the P0304 code.
Do a wet compression test (squirt a little oil into the cylinder). You can also do a running compression test, just remove the schrader valve from the end of the compression tester hose. Test at least cylinder #1 and one of the stronger cylinders so we have a comparison.