took the truck to the dyno tuner noticed a cylinder 5 misfire. I swapped coil and injector on the dyno. Still had cylinder 5 misfire. Changed plug wire and plug. Still cylinder 5 misfire. Came home traced all the injector and coils back to the pcm everything was good. Did a compression test all the cylinders matched up. Today I pulled the head valves and lifters were fine. Cylinder walls look good. The way I have been testing it was on the hptuner scanner I turn off an individual injector and you can hear the engine make a noticeable change and runs rough. When I turn off cylinder 5 there's no change at all. I pulled the rail off the intake and verified the injector is firing...it is. Now idk what else to check.

 

Plug carbon tracking? Cracked?

 

Plug is clean. You can see on the strap that it has spark to the strap

 

 

I also replaced the plug and plug wire

 

Took the head to the shop today. They said it seemed like the exhaust valve wasn't sealing so I had them cut and clean all the valve seats

 

Im assuming you used known good parts from other cylinders when you switched and then switched back assuring they werent damaged in the process with no change. I've gotten bad new parts before. Go through it again to verify one more time...sucks.

 

Yup I took the known good coil and injector from 3 took the suspect injector and coil from 5 and put them on 3. With the known good injector and coil on 5 cylinder 5 still misfired. Cylinder 3 ran fine with the suspect parts from cylinder 5.

 

Have you tried SeaFoam'ing it yet?

I'd get some DeepCreep and spray directly into the cylinder, let it sit, fire it up, rev it a few times (it's going to smoke like hell) and then SeaFoam the regular way.