It seems like it has a slight miss but not sure. Valve train all good. New coil and good power to coil and good power to injector, injector is good, fuel pump new, swapped coils around, swapped injectors around. Kind of stumped on this one. I've got a picture of my power balance and a known good power balance.

This is my power balance and as you can see cylinder 1 seems to be low.

This is my mom's excursion with the 6.8 and it stays a whole lot steadier.

 

I guess the next step is to swap the spark plugs and see if the problem follows the plug or stays on #1.

If the problem stays on #1, then you likely have a mechanical issue to sort out. That could be anything from a failed head gasket, broken piston rings, cracked piston, gouged cylinder wall, bad valve seat, bad valve, or even worn camshaft lobes.

A mechanical compression test and leakdown test might be beneficial.

 

You never mentioned inspecting and/or replacing the spark plug on #1, did you already do that? Swapping coils/injectors, I hope you pulled all the plugs to run a compression test? How did you validate the valvetrain was good? Visual or by test?

How do you like that Maxicom? I want to get one someday!

 

Spark plug looked good visually. Valvetrain visually looks good though whole timing chain assembly is about a year old and so is passenger side rockers and lifters. Engine is a reman for Ford from 2018 so I wouldn't think mechanically anything is wrong, gets service done every 4000 miles. Also spark plugs aren't even a year old yet and are motorcraft platinums. So far I like the maxicom, does what I need.

 

Failed head gasket, would there be other signs? Not loosing coolant and oil is clean. Camshaft lobes good, just looked at those the other day. I might pickup a new plug and send my camera down the plug hole and check piston and cylinder wall

 

I think I would still swap plug and coil, just to absolutely rule them out.

 

A head gasket failure might have coolant in the oil, or oil in the coolant, or cause pressure to build in the coolant recovery bottle, but these symptoms could be caused by other issues, so the symptom is not a reliable indicator for a head gasket failure. It just indicates that there is a problem, and you hope it is a head gasket failure because the repair price for the other issues escalates very quickly.

If a compression test indicated low compression in 2 adjacent cylinders, that if a more positive indication that there is a head gasket issue, but still this isn’t 100% reliable.

Only removing the heads and autopsying the gaskets will tell you with 100% accuracy.

 

I did a compression test on cylinder 1 and 2 to see if there was a difference but we're about the same. I know I need to do them all but what should the pressure be?

 

The Ford Workshop Manual only provides a table of MIN/MAX readings and no nominal value. I'd search Google, but assuming anything in the 150psi range would be considered acceptable(?). The Workshop manual states that the lowest reading should be within 75% of the highest reading. (Example: Min 135psi and Max 180psi)

What you should do is ensure you're up to operating temperature, pull all the plugs out, then run the compression test. On a 4 banger, this seems easy enough, but I'd imagine by the time you snaked out all the plugs on the V10, it would be cold!