6.4 with miss

[zukgod1]

Ok so we have this truck in our shop. Came in with a mis.
Was diagnosed at another shop with bad injectors. We double checked and and sure enough had 4 cyl had bad contribution.
We pulled all 8 injectors and had them tested and all 8 tested good.
Customer decided to change the 4 "Bad" ones anyway.
It's back together and same deal.
We did a compression test and all were over 310 psi and within 15psi between all 8 holes.

Not making any noise at all, sounds fine but has a mis. When the converter locks its REALLY prominent.

Ideas?

 

[DieselLance]

pull the rocker arms and check the valve side of them

 

[zukgod1]

I'm not sure what you mean. Check the wear?

 

[Scooter's Roofing]

I bought a 6.4 with a slight miss recently...

passed relative compression

one of the #6 pushrods looked like an S and rolling the motor you can feel a bent rod

good times

 

[wise guy]

310 is low 99% of 6.4 missfire problems are base engine bad lifter, bent push rod, bad rocker arm , burnt/ bent valves or melted/cracked pistons bent rod ect...

 

[DieselLance]

the valve end of the rocker arm will be missing part/all of the ball where it contacts the valve

 

[zukgod1]

It's scheduled to get back inside Monday.
I'll report back once we get the rockers out.