jbone2470 wrote:I was gonna say swap the #4 with #5 coil and see if code follows and still runs crappy. The code u got was a p0304 if it was the #4 cyl.
Also did ya double check the spark plug gaps..Those coil harness plugs can get dirty or malfunction.Check the connection carefully.
If all that doesn't work then try check the injector,did ya replace the o rings while u had them off? If all else fails then a compression test leak down test might be in order to see what is the problem.Hopefully not valves.
Did you take off the whole harness off all 3 coils? if so did ya put it back on backwards? I interested in the outcome.keep posted.
I swapped #4 and #5 coil and reset the check engine light. After 15 minutes of driving, the p0304 : cylinder #4 misfire code was revealed with the OBD-II scanner again. So it definitely is not the coil.
The spark plugs are all new and I checked their gap as I put them in so that is correct. The coil harness plugs are all clean; in fact it looks like the previous owner might have had the coil harness plug replaced on cylinder 4 because it looks identical except the markings on the harness aren't the same as the other 5 are and it looks to be newer.
The injectors I didn't remove from the fuel rail when i changed the intake manifold gaskets and pcv valve. I was avoiding that because I didn't want to tear a new o-ring and have a fuel leak to deal with.
The harnesses for the coils I did one by one as to make sure I didn't put them in improper order when I did the tune up.
I guess it could be the fuel injector, the wire leading from the coil harness back to the main harness, or there could be bad compression in that cylinder for whatever reason. I'll go get a compression test and keep looking. Its not looking very optimistic at this point.