I have a PO340, PO344, PO345, PO553, and occasionally brings a PO303 and a PO316. My timing chain recently knocked a hole in the valve cover. Had it removed to find there was nothing wrong underneath. Welded the cover back up put it back on drove fine for 2 days. Started knocking. But when I turn it off and turn it back on it runs perfectly fine. But now its to the point where it wont run worth ****. The mechanic thinks the problem is in the wiring. I have no idea. What do you fellas think?

EDIT: There was another code as well and I believe it was PO320.

 

if you had a hole knocked out of the timing chain then there's a problem....

cam chain tensioners
cam phasers

was the cam put back into time with the motor crank????

 

He checked em out too. When he got the valve cover off he didn't find a single thing wrong. The only reason I found it was because I could smell burning oil when I stopped at lights so I'm assuming it never come out of time. How in the hell that happened ill never know.

 

Pre-detonation firing on multiple cylinders. Can't tell for sure how many but it's a couple of em for sure.

 

How in the hell could a timing chain knock a hole in a valve cover and nothing be wrong?
I know i'm not the sharpest tool in the shed,but jeez, you would think something had to malfunction somewhere along the line.

 

Alright so I've found the problem. The hole know in the valve cover was not the chain itself, it was one of the guides launched through it. The timing is off. So I have to fork out a chunk of change to have a new timing chain kit put in.

 

I am going through somewhat of what you are. The entire problem I have started with collapsed valve lifters. I have no idea how many miles your engine has. It's worth the $$$ to replace them if you've got high miles. Hope you don't have a trashed valve train already.