2009 Dodge Ram 2500
5.7l Hemi
225,XXX Miles

*Truck idles good, no ticks or funny sounds, idles very smoothly.
*Misfire happens under WOT on cylinder #4.
*Check Engine light will begin flashing.
*Truck will then idle rough.

Waiting several minutes or restarting truck repeats the process once WOT happens again.

Coil/Spark plug have been changed.

 

Check compression, or, down a cylinder leakdown test. (or both....) See what the numbers look like.

Maybe broken valve spring?

 

At shop.

Compression checked good.
Injector GOOD.
Coil GOOD.
Sparkplug GOOD.

Computer shows constant misfire.
Currently checking electrical... will update...

I asked about possible broken valve spring on that cylinder and he warned it was a "massive job".

I called dealer and they quoted $372 labor for intake side.

 

It really isn't that bad of a job, just time consuming.

 

Update:

Shop believes it has a burnt valve on cylinder#4.

Says head has to come off...