The pickup runs good but idles a little rough. (130,000 miles) OBD2 test shows a misfire in the #4 cylinder so I put all new plugs and plug wires, new coil pack and fuel injector in the #4 cylinder, new fuel filter, and checked pcv valve and air filter, both are good. Check engine lite is still on and it idles a little better but still rough. I haven't done a compression check....was wondering if anyone had any other ideas on what else it could be.
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missfire #4 cylinder 1999 gmc sierra 5.3
- Thread starter sedme1
- Start date
What was the code and were there any other codes stored? Is it P0304 and if so is there another code? Usually and new coil pack with the plug wire and a new plug will take care of the problem. Try clearing the code and then see if it comes up again.