gm558
Member
- Joined
- June 18, 2008
- Messages
- 20
- Reaction score
- 0
- City, State
- Zanesville, Oh
- Year, Model & Trim Level
- 2005 Limited 4.6
My '96 Sport 4.0 has 235,000 miles on it. I get a repeated p0303 (cyl 3 misfire) every few days. It has been well taken care of and uses no oil between changes. It has new Autolite Double Platinum plugs, NAPA wires & coil, new injector on #3 cylinder, new cats, O2 sensors, EGR, DPFE, vacum lines, etc. It will run great for a few days with a new plug in #3 and then begin to misfire. When removed the plug porcelin is brownish-yellow but not fouled. There is some oil residue on the threads of the plug. , I do not have a leaking valve cover. A compression test gave 150 psi in that cylinder. Anyone have experience with this?