Plug wire arcing
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Plug wire arcing
I have a 94 F-150 with a 302 and am having problems with my plug wires arcing. The spark jumps from under the boot to the exhaust manifold on the whole right bank. I checked it at night when I could see it really good. The wires are all new, but I double checked thier resistance anyway and they are fine. They are all very well seperated from each other with rubber seperators and are no where near metal or each other. The plug gap is dead on and the resistance is all very close. I had replaced the coil a while back because the tip was so erroded away that the wire would pop off if you jiggled it. I also replaced the capacitor/noise filter. The cap and rotor were replaced as part of a tune up and they are still good. The truck runs OK. It misses every now and then and idles a little rough. Mileage is down the tubes. The O2 sensor is really confused, it shows rich and lean at the same time. What I can't figure out is why the spark is jumping such a long way to the manifold, and not across the plug gap like it is supposed to.
Posting Guru
Joined: Jun 1999
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From: Durham
Plug wire arcing
First, use some dielectric grease and put some inside the boot that goes over the plug, then make sure that the boot is seated properly. Sometimes, especially if you crimp your own wires, the connector that snaps down on the plug gets squeezed too tight and does not mate with the plug properly.
'82 F150 w/351W (orig 300 I6)
Slik
'82 F150 w/351W (orig 300 I6)
Slik
Posting Guru
Joined: Sep 1999
Posts: 2,297
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From: Indiana
Plug wire arcing
This won't be popular, but replace the wires. I have purchased new wires and had them do the very same thing. Mine were shorting everywhere. After that I only purchased the highest quality wires I could find. I did the same thing, I checked them with an ohm meter, showed good. Routed good. They were even a lifetime warranty wire. Needless to say I returned them quickly. The Accel wires I installed afterward were fine. Good luck!
Posting Guru
Joined: Sep 1999
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From: Indiana
Plug wire arcing
Also have you checked that spark plug itself with an ohm meter? Check it and compare it with some of the others. The plug could have high resistance. Stranger things have happened.
Postmaster
Joined: Jul 1999
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Plug wire arcing
Only time I have ever seen fire jump from under the spark plug wire to ground is because the plug(s) were dead ...Plus its only the ones on the right hand side . Id bet you have 4 dead plugs over there . I assume these are all new plugs ? What brand of spark plugs ? Something that I have seen that will kill plugs is water ...driven thru any deep water ..its the cold water coming in contact with the hot plugs that seems to kill them.
Paul
Paul
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Plug wire arcing
Here's another thought if all else fails. It's based on required spark output,under cylinder pressures,to ignite the fuel mixture. Ok, the injectors are bank fired, right? One left bank,one right bank.Let's suppose the fuel deliverd by the right hand bank is a lil too much for the spark plug to handle igniting,and with the coil having to build up as much voltage as possible( coil output is directly related to cylinder pressures & fuel mixture)to ignite the compressed mixture, the " unused" voltage has to seek another ground path,hence, the arcing from the plug boot to plug shell. Once the coil releases it's voltage, it all has to go somewhere,and, if the voltage was not completely used up in the combustion process,it's got to go somewhere else. This is stuff I learned from reading Jacob's book on ignition.It's an awesome book that goes real deep into the total ignition aspect.
Phillip
Phillip
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