I have been working on this motor for some time and getting it sounding/running better, but I still can't get rid of this backfire. Here is the scenario:
The truck starts, runs, and upon start it backfires and doesn't stop. The backfire goes from a load pop to a muffled pop. I went through and removed individually and upon getting to cylinder 3 and removing the power to the coil pack the engine stops backfiring. After a minute or less I can replace the power to the coil pack and the motor does not backfire anymore. However, if I shut the truck off and restart the motor the backfire returns. I have replaced all of the coil packs, all the plugs, gapped the plugs, and swapped injectors from 1 to 3 and 3 to 1 and the backfire continues.
Does anyone have any thoughts? Can the timing be advanced on just one coil or cylinder?
I appreciate all of the past help and anything going forward.