another 98 4.6 #4 missfire... searched a lot
 

Here's the scoop. I just bought a 98 2wd f150 supercab 4.6 windsor with 131K on it. I paid 2100 for it cuz it was knocking. I pulled the head off the pass side and found a bad piston in #3 hole. Replaced the piston, bearing, and rings. I put it together with all new mostly motorcraft gaskets and seals. I now have a missfire on #4.

Conditions: Btw i did pull the harness away from the a/c accum. and i seemed to help !

I can reset the computer. Engine runs pretty well and has decent power around town. If i get on the interstate and drive for a while it's fine. As soon as i get off the exit... and then start again from a stop sign or light the CEL starts blinking... eventually it will go solid. The ONLY code i've gotten is a #4 missfire. After the cel comes on the motor runs more rough than it did before. I pulled each fuel injector while running and all seemed equal. I just replaced the wires and plugs. I used autolite double plats. I've double checked that the wires are plugged in and seated all the way on the plugs. I've pulled #4 plug and unplugged all the fuel injectors and turned it over. nice blue, consistant spark.
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Anyone have any thoghts? I'm going to swap coil packs tomarrow to see if the missfire moves. FYI the only cyclinder/piston that looked bad was #3. The others looked to be in perfect shape. The head looked fine as well and i put new valve seals in as well.

Can a 4 way coil pack have just one bad corner?

Thanks for any help
Adam

Hi Adam , from what I 've read the answere is yes to your question. I have the COP,s system on my 98 but people generaly use eBay to get there COP's or Coil Pacs when they need them . You can get mew one's at a 75% discount if you keep an eye out for them.

When these motors get up there in milage COP's & Coil Pacs weaken which can result in poor performance and very bad gas milage.

I suggest swapping them out for new ones. It's morless the ultimate tune up. :D