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Discussion Starter · #1 ·
Hi, I had been experiencing a very intermittent cylinder #1 misfire. No misfires on any of the other cylinders. I first installed a new coil pack and the problem did not recur for several weeks. For the next step, I checked the coil connector, cleaned it, and then I re-connected the cable. The problem reoccured after two (2) weeks. Then I swapped the coil pack and spark plug with cylinder #2, and the random misfire returned. At this point, I decided the problem must be the injector, so I replaced the injector. Unfortunately, the random misfire still occurred.

The problem was very frustrating to troubleshoot because if you drove for 20 minutes you may not get any misfires and they may not return for several trips. Another complication is the engine cover prevents access to the coil pack harness and the fuel injector harness when the car is running. Therefore, you do not have the option to "jiggle" or move the harnesses and connectors to see if you can get the problem to occur consistently.

I lived with the problem for another two (2) months and tried to ignore it. I was planning to perform a compression test because maybe a piston ring or a sticking valve was causing the problem. I changed the oil religiously, so I was confident it was not a mechanical problem. I thought maybe the problem was carbon build-up. So yesterday I drove the car hard to hopefully free the stuck rings or valves. The problem started to repeat at a high rate and I was scared that there was a mechanical problem. I let the car cool down, started the engine and there was no misfire.

Late last night I remember seeing a post on this site about a 2009 Malibu with a misfire that was caused by a damaged fuel injector wire. The post includes two (2) users that had the same problem. Before leaving for work today I decided to remove the engine cover and inspect the wiring the Fuel Injector #1. I removed the electrical tape up to the harness and inspected the wiring without any observations. Then I decided to remove the tape at the junction of the wiring and the cable harness. Oh my god!!! There it was, the black wire was damaged and only a few strands were left at one point. The wire was damaged about 1/4" in the harness.

I repaired the wire that the engine is running super smooth, and there were no misfires today!

Check the harness wiring for the injectors!!!!
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