01350ss

iTrader: (18)

2003 yukon 5.3 flex fuel - no mods bone stock 131,xxx miles
already replaced intake gasket with updated years ago

developed a misfire a couple weeks back that was intermittent. finally tripped a code, read it and showed only p0303

here is what ive done and the results in the order of completion:

swapped coil from 3 to 4 - miss stays on 3
swapped wire from 3 to 4 - miss stays on 3
swapped plug from 3 to 4 - miss stays on 3
swapped injector from 3 to 4 - miss stays on 3
swapped ENTIRE coil bridge from driver to passenger - miss now on cyl 6
removed coil harness from passenger coil bridge and have continuity from main connector to each coil pigtail, also inspected for damage/breaks - none
swapped coil harness from passenger to driver - miss stays on 6

seeing as the misfire moved, that rules out internal engine

thoughts? my truck is at my shop right now so i cant go check or move on to the next until tomorrow morning.

01350ss

iTrader: (18)

traced to a coil

replaced all is well for anybody who comes up with the same/similar issue
this may help