#1
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Misfire on cylinder 3
A few days ago, the engine started running rough and the SES light came on and started flashing. I connected a scanner to the OBD system and got codes P1320 and P0303. These indicate misfiring, specifically on cylinder 3.
I poured a can of BG44K in the gas tank and I continued to drive it a few days to see if an injector was hanging up. I noticed a pattern after a few days. After the engine cools down completely, the engine runs perfectly smooth (no misfire) and will continue to run smooth even after the engine warms up. But after the engine is warm and I shut it off, the misfire returns on restart. So my theory was that the heat was causing the coil on #3 spark plug to malfunction when warm. So today I replaced the coil (coil on plug) and spark plug on #3 cylinder. On startup with a cold engine, the engine still ran rough but no SES light. FYI, the odometer is at 162,000 miles. I replaced all the spark plugs at about 100,00 miles. Any help is appreciated. Last edited by gboone; 06-03-2019 at 07:03 PM. |
#2
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Problem fixed
I took the coil out with it still connected to the harness. Then put the old spark plug in it and started the engine. I put the ground electrode of the spark plug against a ground and the spark was strong and consistent. So I took the new plug out of the engine and could smell gasoline on it, so I knew the injector was working. Put the old spark plug back in and then the new coil. Drove it and everything is good after 2 warm restarts.
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cylinder, misfire |
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