I own a 97 ford f150 xlt v8 4.6L and a few months back i replaced my wires with msd wires. every once in a while my cel comes on and my trucks starts misfiring really bad. obd gives me a misfire on #4. my spark plugs and my coils are new... i tried switching that wire out and it did nothing and then i got a misfire on #3 so i pulled it out put some boot grease on it and put it back in, reset my computer and i was good to go. today it did it again and the obd said misfire on #4 again. i looked through my haynes manual did a couple of checks on some sensors and what not and everything was fine. i just unplugged my #4 wire from the spark plug and before i put it back on i greased it, then the problem was pretty much gone and my cel doesn't start flashing like before. it almost seems as soon as the grease dries up or whatever this problem starts again. has anyone had problems with msd wires? any suggestions?

 

What plugs are in and how old are they?

 

yeh my MSD wires gave me problem they fit in the plug well but dont seal to well around the port so water gets down i nthere easily.. i basically filled the plug boot complelty full of the dielectric grease and it solved my problem