97 F150 5.4 w 128k. It threw a P0304 code (#4 cylinder - rear passanger side) last week when moving it in the driveway. I've read all about P0304 codes and there solutions in this great forum. I knew tighting the heater hose clamp (already had the screw clamp stlye) and replacing spark plug and COP coil asy. would fix the problem. So I picked up a COP and spark plug at Autozone and when to work. COP and spark plug that were removed virually looked good and there was no water or any anti-freeze solution deposits anywhere. I still went ahead and changed the COP and plug. When I started it up it still skipped (mis-fired)for about 15 secs and seem to straighten out. Went for a ride to check things out and to my amazement 3-4 miles later skip is back. Same code P0304 and the smell of rotten eggs. Where do I go from here ? Help.

 

I'd swap injectors with #1 and see if the fault stays on #4 or moves to #1.

If it stays, you may have a valve problem or a wiring problem specific to either the injector or coil connections.

Steve

 

Well I finally got back to this problem this afternoon. I took projectSHO89 advise and swapped #1 and #4 injectors after I checking the spark output of #4 coil (used AmPro High Energy Ignition Spark Tester) which looked real good. I then disconnected the battery and swapped injectors. Checked code with (Acton CP9175) scanner only to find the P0304 code was gone. I then started the 5.4 and to my amazement it had no more misfire or skip. I took it for a 15 mile drive cycle and all is well. Strange. Anyone care to comment.