I rebuilt 2010 5.0 super using all necessary timing tools etc . Starts up and after some miles break in clearing codes etc with gap tool and other obd scanners I get the following . Misfire codes P0300-00, p0313-00, P0316-00. Short term fuel trim is -9.375 bank1, -17.969 bank 2. Bank 2 is an issue with misfire codes on Cyl 8. Have done the coil swap, plug swap and new injectors in bank 2. Compression is 125 psi in all cyls on that bank. Swapped injector cyl 8 to be sure . Still the same.

So if compression is good, swapping coil,plug and injector doesn't change anything .............. could improper valve clearance cause this ongoing misfire codes for cyl 8? I've replaced all valves with new , lapped in etc and shimmed clearance with new tappets as needed.
I need guidance from here.........my head hurts from it.

 

Why was the engine overhauled?

How many kilometres/miles are showing on the instrument cluster?

Negative fuel trims indicate mixture is too rich and the PCM/ECM is attempting to make the mixture lean.

If the MIL is flashing, find and correct the cause(s) of the misfire(s) or the catalysts are going to be damaged.

 

Are you sure you timed the fuel pumps properly ?