Reply To: Bent spark plug ground electrode causing P0302

[Richard Kirshy]

If the correct plugs are installed and gaped properly.
That would leave some type of mechanical issue.
I would reinspect the inside of the cylinder very carefully with a borescope.
Might also look for some type of thread repair that may have been performed on the head on that specific cylinder.
Beyond that, you may well need to remove the head to actually see what is happening inside that cylinder.