code P0304

I would check compression on all cylinders, lowest psi must be within 20% of high.

If compression is OK, then I would suspect a clogged convertor.

If compression on one or more cylinders is higher than 20%, then you will have to remove head.

I have been working on this project for a month!!
The truck was basically dropped of in my yard with a thrown rod. I bought a used motor and threw it in.

When writing my first email i failed to tell you that i replaced the converter first and it did not change my problem. I also had a lean code in bank one and a EVAC code

I then changed out O2 sensors with new - still code P0304.

That is when i continued to change out parts. Everything i changed out made the truck run better and better. But never got rid of the P0304 code.

When replacing all the parts listed in email one didn't cure my problem I pulled the valve cover to look at the cam which was in good shape. I did find the oil pump pulley bent slightly so I put a salvaged one on.

That is where I am today. I am an ASE certified School Bus Mechanic so I dont see a lot of gas engine but do feel I am knowledgeable enough to take on this project however this has me stumped.

Any ideas are welcome!!

Check compression on all cylinders to rule out a mechanical problem.

If you have access to scanner, scan in live data mode, look for sensors out of range.