Well wouldn't be posting if I wasn't fairly stumped on this one.

Swapped a 56k og mile 97 motor in my 96 Fsuperduty. Ton of new parts, valve cover gaskets, efuel, and 160/30 CNC Fab injectors. Truck ran great for about 2000 miles. Put it in a 100hp tune one day and ripped it up a pretty steep hill empty and it started smoking bad white smoke for about 5 mins. Drove it home and it went away but just never felt like it was running right after that. rougher idle, harder cold starts, and sounded almost imbalanced above 2500rpm. So I got a cord and forscan and did a buzz test, they all buzzed fine. Did 3 cylinder contribution tests and it failed #2 cylinder 3 times in a row.

Next step was pull the valve cover, valve train all looks fine, pulled a glowplug and did a compression test, 420psi in that hole. so figured it had to be something internal in the injector. Sent it back to Eric at CNCfab and he just emailed me a couple days ago saying the injector is all good sending it back.

looking for any ideas from the gurus because it seems like I've covered mechanical engine is fine, the electrical and the mechanical parts of the injector are fine. Not sure what to even check from here other then possibly swapping a couple injectors, wire harness, or valve cover gasket and seeing if this misfire moves cylinders.

 

Do you have an EGT gauge?

what turbo and do you have an intercooler?

I would consider scoping the cylinders to check the condition of the pistons.

 

Steep hill for a mile or 10 miles?

What is compression on rest of bank?

Try swapping 2 and 4 to see if issue moves?

 

Full of oil?

These make a lot of noise and run poorly when low. BTDT

 

Need to check compression on all 8 cylinders, there's a chance of having a bent push rod or valve if you dont have upgraded valve springs.