Engine 91 LX New Plug Wires Arcing

Barron91lx

Member
Dec 21, 2018
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Newton, KS
I've looked all over online to find a good answer to why my new plug wires would be arcing and can't find one.
A quick rundown on my car: 91 LX 5.0l. I just put a new Blueprint engine in last summer. It has almost 500 miles. I have replaced every sensor and solenoid I can find. It has a new MSD distributor. It misses out until it warms up then runs great. Last week I opened the hood in the dark and noticed there was arcing on nearly every plug wire. They were new last year but it was an opportunity to upgrade, so I put on a new set of custom length MSD wires. I opened the hood in the dark this week and was very surprised to see the exact same thing. Every wire was arcing to some extent. The most interesting part is that when I touch the coil wire and run my fingers along it, the light arcing follows. Btw, I did put a new stock coil in last year too and it has new plugs gasped at .45. I did repaint the engine bay when the engine was out. Is it possible the coil isn't grounded good enough because of the paint?

Thanks,
Mike
 
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dgollem

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Sounds weird, I'm suprised you didn't get shocked from a bad wire. Don't think the paint is causing any issues. I would just get a new set of Ford racing wires, never had any problems with them and they are 40 -50 bucks from most of the online venders including summit.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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Go back and make sure all the engine grounds are good. Metal to metal contact. There are four, the battery ground to block (bolted to the block, not a bracket or the timing cover) a small black wire from the negative battery cable to the inner fender apron between the battery and the solenoid that has another black wire that runs into the wire harness below, the block to firewall ground that is bolted to the drivers side head in the rear and has a sheet metal screw to the firewall nearby, a ground that comes out of the injector harness and bolts to the passenger side of the intake or head behind the throttle body/egr valve area.
 
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jrichker

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Is this what you are seeing?

View: https://www.youtube.com/watch?v=Klqlxc0uzHo

Text from:
http://www.auroraelectronics.com/corona effect.pdf

Corona Effect, also known as corona discharge, is a rare phenomenon that can cause a glow on spark plug wires. This event (visible in the dark) appears as a bluish-white glow around the spark plug wires, and may branch between wires or to a ground surface. Corona discharge does not necessarily indicate a problem with the spark plug wires, but more likely a maintenance or installation issue. This discharge is virtually silent as compared to the snapping noise heard when a wire is actually leaking high voltage.

The cause of corona discharge is the ionization (making conductive) of the surrounding air. Ionization releases electrons from the oxygen molecules; the resultant energy release creates photons (light) to be produced. This ionization is caused by the presence of large voltage differentials pulsing in the wire.

Certain contaminants on the jacket of a spark plug wire can enhance the likelihood of this phenomenon to appear, such as accumulations of oils, dirt, or paint overspray. Spark plug wire routing will also have an effect. If spark plug wires are allowed to touch a ground surface, or if they are bundled together, the chance of corona discharge is greater. Alternate fuel vehicles, such as propane or natural gas powered, can see increased likelihood of corona discharge as well. Residual vapors from these fuels cause easier ionization of the surrounding air.

To minimize the chance of corona discharge, spark plug wires should be kept relatively clean and free of noticeable amounts of contaminants. Spark plug wires should also never rub against metal engine parts, such as valve covers. Proper loom clips should be used to separate spark plug wires; avoid bundling them together with cable ties.
 
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Barron91lx

Member
Dec 21, 2018
26
3
13
48
Newton, KS
Sounds weird, I'm suprised you didn't get shocked from a bad wire. Don't think the paint is causing any issues. I would just get a new set of Ford racing wires, never had any problems with them and they are 40 -50 bucks from most of the online venders including summit.
I don't mind getting a new set of Ford wires but the MSD wires I paid $100 for are two weeks old
 

Barron91lx

Member
Dec 21, 2018
26
3
13
48
Newton, KS
Go back and make sure all the engine grounds are good. Metal to metal contact. There are four, the battery ground to block (bolted to the block, not a bracket or the timing cover) a small black wire from the negative battery cable to the inner fender apron between the battery and the solenoid that has another black wire that runs into the wire harness below, the block to firewall ground that is bolted to the drivers side head in the rear and has a sheet metal screw to the firewall nearby, a ground that comes out of the injector harness and bolts to the passenger side of the intake or head behind the throttle body/egr valve area.
Thanks, I checked all of those and they looked good. The ground to the harness was connected to the body to engine ground though. I reconnected it to the intake.
 
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Barron91lx

Member
Dec 21, 2018
26
3
13
48
Newton, KS
Is this what you are seeing?

View: https://www.youtube.com/watch?v=Klqlxc0uzHo

Text from:
http://www.auroraelectronics.com/corona effect.pdf

Corona Effect, also known as corona discharge, is a rare phenomenon that can cause a glow on spark plug wires. This event (visible in the dark) appears as a bluish-white glow around the spark plug wires, and may branch between wires or to a ground surface. Corona discharge does not necessarily indicate a problem with the spark plug wires, but more likely a maintenance or installation issue. This discharge is virtually silent as compared to the snapping noise heard when a wire is actually leaking high voltage.

The cause of corona discharge is the ionization (making conductive) of the surrounding air. Ionization releases electrons from the oxygen molecules; the resultant energy release creates photons (light) to be produced. This ionization is caused by the presence of large voltage differentials pulsing in the wire.

Certain contaminants on the jacket of a spark plug wire can enhance the likelihood of this phenomenon to appear, such as accumulations of oils, dirt, or paint overspray. Spark plug wire routing will also have an effect. If spark plug wires are allowed to touch a ground surface, or if they are bundled together, the chance of corona discharge is greater. Alternate fuel vehicles, such as propane or natural gas powered, can see increased likelihood of corona discharge as well. Residual vapors from these fuels cause easier ionization of the surrounding air.

To minimize the chance of corona discharge, spark plug wires should be kept relatively clean and free of noticeable amounts of contaminants. Spark plug wires should also never rub against metal engine parts, such as valve covers. Proper loom clips should be used to separate spark plug wires; avoid bundling them together with cable ties.
Thanks for the corona info. That is exactly how it appears. Last night I was checking it out and my friend noticed light coming from under the alternator pully. It looked almost like corona flowing onto the belt as it turned. I haven't ever seen an alternator do that. The alternator is just a few months old.