97 Expy eats #4 plug
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Senior User
Joined: Jan 2004
Posts: 330
Likes: 0
97 Expy eats #4 plug
My 97 Explorer 4.0L code X is really rough on the #4 plug, I have to change it on a regualr basis. CEL throws 304 code, misfire #4. After I change the plug and reset the PCM I am good to go for anywhere from 2 weeks to 2 months but when it starts to runs rough I know the code is gonna pop again. I've used Autolite AP103, Bosch (no good), Champion, Denso (why?) all with the same result.
I've changed the coilpack about a year ago, upper/lower mainfold gaskets 2 yrs ago, injector cleaner now and then. Any ideas out there?
Thanks
I've changed the coilpack about a year ago, upper/lower mainfold gaskets 2 yrs ago, injector cleaner now and then. Any ideas out there?
Thanks
Posting Guru
Joined: Aug 2000
Posts: 1,984
Likes: 2
I too would suspect a bad plug wire.
If you have an ohmmeter, you can test it; should have about 6-10K ohms per foot of wire. The number 4 is the longest of all the wires, and therefore has the most resistance.
If you have an ohmmeter, you can test it; should have about 6-10K ohms per foot of wire. The number 4 is the longest of all the wires, and therefore has the most resistance.
Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
If the plug is fouling out, I would second the wires as a possible culprit. If the plug is eroding away at an accelerated rate, I would be led to believe that the cylinder is leaning out, due to a plugged injector, leaking intake manifold, etc.
