Iím getting a P0304 Code - Cylinder #4 Misfire code on my 2001 SEL. Iíve seen the various threads on this issue on how to trouble shoot it. However, Iíd like to know, how serious is this problem? The only symptom Iíve noticed is that the car occasionally runs rough when idling. Otherwise, the car runs fine. Is this something that needs to be addressed immediately, at risk of ruininng the engine? I do intend to deal with it, I just may not be able to get to it until two weeks or so, but I drive the car 50 miles every day. Iím also aware that Iím using only 5/6 thís of the engineís power and probably wasting gas. Thanks.
the cats are already 10yrs old. with the unburned gas getting dumped into it there really isnt telling how long it will last. the fix might be easy, a plug/wire.
There are cars that drive for months on a misfire with no issues. But i have been burned in the past with the cat getting clogged from one.
Okay, I replaced the spark plug, no resolution. (Noticed what appeared to be a drop of possibly oil on the spark plug tip? Not sure if oil or gas.) I replaced the wire to that cylinder, no resolution. Next step, I’ll change the coil. If changing the coil doesn’t work, next step check the fuel injector (groan)?
Okay, changed plug, no resolution. Changed spark plug wires, ditto. I replaced the coil last night. Keeping fingers crossed for the test drive this morning. I got held up on changing the coil since my 2001 24 valve duratec SEL was blessed with Torx bolts affixing the coil to the engine block. Oh goodie! So had to run out and buy a Torx screw driver set. The previous posts said it was size T25 or T27. It was 25 on mine. I had no problem doing it once I removed the cowl covering over the cabin filter.