Escott16

Check engine light when wide open throttle above 4500 rpm. Code p0304 cylinder 4 misfire.

Replaced

-spark plugs

-mass airflow sensor

-valve cover gasket passenger side (along cyc 1,2,3)(needed done while doing this)

-tested fuel pressure and get proper pressure

-swapped coil pack and fuel injector with another cylinder and still constant misfire cylinder 4

Russell Ormerod

A good start would be to tell us what engine you taking about!
also some history of how this misfire started. Previous work done?

Escott16

I am sorry didn’t even think to, it’s a 2001 C320 with 120k miles and it kind of came out of no where I noticed it trying to merge fast one day erased the code and the car runs fine and only does the misfire when above 4500rpm and I noticed my valve covers leaking oil into spark plugs so I changed the plugs and gasket hoping it was related but it wasn’t

Russell Ormerod

Any work ever been done on the gearbox? Flexplate? Gearbox removed maybe?

Escott16

No work outside what I’ve mentioned

Russell Ormerod

Okay. For that kind of misfire.. do you have DAS? Do a default initialization and recheck

Escott16

I do not. Just a scanner

Russell Ormerod

Find someone with DAS
also you need scope the crank signal. I would like to see how it looks

Escott16

Is the scope thing something I can do. I have a decently equipped garage

Russell Ormerod

Then post a print out of the oscilloscope signal from the crank sensor at idle speed. Showing 1 revolution of the crankshaft