I washed my engine yesterday. Never had a problem with any other vehicles before. After washing I let it idle for about 5 minutes. This was yesterday. Now today when I start it it idles rough and is throughing P0304 Cylinder 4 Misfire. What did that wash do?

 

I forget if cyl 4 has a coil pack or a ignition wire. Anyway, it may have compromised insulation and the water encouraged it to start arcing. You likely need a wire or coil pack.

I have sprayed my engine with water plenty of times (today in fact) and have not had a problem.
Stan

 

Stan, thanks for the reply. What is your trick to washing that keeps you from having this problem?

I took off the cover and pulled the wire off of cylinder 4. It had water about 1/4 the way up. I think we can be safe to say that the coil is still good since it is not coding on cylinder 1? Where do you recommend I order a new wire from?

Thanks again.

 

I'd get wires from Volvo or I think IPD.com has some.

I don't do anything special. I just take a wet cloth to give it a quick wipe and spray it off. I don't saturate the engine.

Your boot does not seem to be sealing very well. One thing you might try is putting some dielectric grease around the boot where it seals to the opening of in the head. You can get the grease from most auto parts stores.