Well, here goes. I have a 1998 4.6L expedition and over the past two months have had three separate misfire codes. I have replaced the spark plugs and been told by the ford dealership that the wires were fine. The computer has been re-set three times and each time has come back with a differnt cylinder misfire code P0308, P0301 and P0303. These are the only error codes that I am getting. The engine has a rough idle when in gear and the check engine light starts to flash when under light acceleration. Since the misfire is random, could both coils be bad? Or should I be looking to some sort of idle sensor? Very frustrating.

 

If you don,t mind me asking what was the fix for you error codes and misfire.

 

If you don't mind me asking what was the fix for the misfire, and error codes.

 

As usual. the dealership did not know what they were talking about, the wire were bad. Replaced them and the truck has run fine ever since.

 

Glad to hear all's well.

 

My son replaced the plugs and wires about 8,000 miles ago, with no problems at all during that time. Then about 1,000 miles ago, the "check engine" light came on and stayed on. I rechecked the wires and checked for vacuum leaks, and found nothing wrong. AutoZone ran the codes and we first got a code P0300, which is a "random multiple misfire". Not much to go on. They reset the computer and a couple weeks later the "check engine" light came on again. A code P0303, "plug 3 misfire" popped out of the computer. I checked plug 3 and found nothing wrong. The weird thing is that this afternoon the "check engine" light went out, and has not come on again after about 50 miles of driving.

My son-in-law, a Ford mechanic, had previously told me to run some injector cleaner through the engine because he thought the number 3 injector was clogged. Turned out he was right. I ran Lucas injector cleaner through three tanks of gas and the "check engine" light mysteriously went out this afternoon. This may be of help to you if your "check engine" light comes on again and you get a code P0303.