Cannot Find Why It Is Fouling These Plugs. The Computer Gives P0304 Which Is Cylinder 4 Misfire.i Have Put In New Plugs,wires Look Good Anybody Had This Problem Before? I Also Recently Switched From Valvoline To Q-state.

Cannot Find Why It Is Fouling These Plugs. The Computer Gives P0304 Which Is Cylinder 4 Misfire.i Have Put In New Plugs,wires Look Good Anybody Had This Problem Before? I Also Recently Switched From Valvoline To Q-state.


Could be a leaking injector.

It was the intake gaskets on the right bank

My '98 is throwing a 306 code,#6 cyl misfire ,#6 plug is fouled too. I had a lot of carbon built up in the intake and on the throttle body plate. Now I have another idea for mine - did you change the intake gasket yourself or did a shop do it?

I had a shop do it.It takes about an hour just to get the wiring harnesses out of the way.The air conditioner pump has to be moved.I watched as he did it,looked like a real pain and cost me about 450.Good luck hope this helped.