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2019 5.7 MPI misfire issue

mhf2467

New member
After rebuilding my engine I keep getting a trouble code for misfire cylinder 1. The engine will go into guardian mode and not go above 2700rpm. This has happened 3-4 times since the rebuild. I have replaced the plug wire, and the spark plug. Once I clear the code the engine will run fine for months and then it will happen again. The last 2 times it happened while running at 3600-3700rpm. The engine will have a loss of power like I reduced the throttle even though nothing was touched. All other systems work fine and the engine will restart and operate fine at lower rpm. Once you try to increase rpm it wont increase above guardian mode setting.
I am not sure what else can contribute to the misfire cylinder code sent to the computer. I thought it could be a fuel injector but they have their own code when not functioning correctly. Anyone have any ideas? I have replaced the spark plug wire and plug twice. Both times I could find nothing wrong with them. I even swapped the #1 with #2 wire and it still produced the same code some months later on cylinder 1 so I dont believe it is parts related.
 
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