I had a P0304 Diagnostic code on my 2003 Dodge Ram 4.7L. this is a #4 cylinder Misfire. I changed My plugs, Fuel Injector and Coil trying to get it to go away. Compression was 150 all around. Finally I started tearing the motor down and under the Valve cover the rocker arm fell out from under the Cam. Talked to the Dodge Dealership and they said this is Common on the 4.7 motor. I fixed the problem 1 lifter and one roller rocker. Has anyone else had this problem?

 

Sounds like bad news for me. My 05 4.7 64k miles is throwing p0301 and have changed coil,plug,injector, and took fuel sample (which was good). I'm going to do a leak down test next. Any comments ... anybody???

 

I just had the same problem and went through pretty much the same steps you just stated. Pull the valve cover and check to make sure your rocker arms are still seated. I had one that fell off and caused the engine to run very rough (Chugging and misfiring through the throttle body) I believe this was my fault because although I am a stickler for changing oil oil, I had run those spark plugs too long and #2 went bad and misfired. I believe the misfire threw the rocker arm.

 

Consider yourself lucky, the other "common" problem with the 4.7 is valve seat failures and I had it happen to me in my Grand Cherokee (4.7 HO) and you don't wanna know what a b*tch it is just to get the heads off of these modular, OHC engines...

 

Yep, several threads of rocker arms falling off on 4.7s.

This is an old thread BTW though.