Blue glow around spark plug wires
Thread Starter
Race Director
Joined: Feb 2001
Posts: 13,913
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From: Manassas VA
NoVa Events Coordinator
St. Jude Donor '14
Blue glow around spark plug wires
I got a misfire code the other day and noticed a blue glow around several spark plugs... Time for new wires? I replaced the AC Delco plugs with Bosch and not codes so far. Car has a set of Taylor wires isntalled. I don’t see any arching but just a very faint constant glow around the plugs…
[Modified by Bluewasp, 12:14 AM 12/8/2002]
[Modified by Bluewasp, 12:14 AM 12/8/2002]
Melting Slicks
Joined: Apr 2000
Posts: 2,793
Likes: 46
From: Elizabeth City, NC
Re: Blue glow around spark plug wires (Bluewasp)
Well grab ahold of it and tell us what you find out. That is the only way to know for sure. :D
But anyway.....yes it's time for new wires.
But anyway.....yes it's time for new wires.
Melting Slicks
Joined: Apr 2002
Posts: 3,019
Likes: 0
From: down that one road next to that big tree
Re: Blue glow around spark plug wires (oldace84)
i've seen this problem a few times, it actually can cause detonation by triggering spark where it shouldn't those sparks if bad enough can actually jump wire to wire. you'll know what this is going on by how the engine runs. like hell is a simple way tp put it, just normal spark leak is less dangerous but still warrents replacing all the wires, cap and rotor. i heavily recomend the msd 8.5mm supercounductor for your wires & also msd for cap & rotor if possible. the msd wires are the most resistant to chemicals and oil i've ran across yet & also the best flowing current wise. 9 out of 10 times your wires leak from a conductive chemical {like oil} soaking into them and letting the spark arc if two wires are sitting on each other. this would cause the misfires etc...if it's not that bad or the wires don't touch you will just have plain ole spark loss. as a personal side note i have not had good luck with taylors chemical resistance as they will leak the first time you spill oil on one or overheat it. my old engine misfired like mad for hundreds of miles, i finally caught on to why one dark night when i could see the sparks jump. i know this is a rather random paragraph but i hope it makes a good point :)
[Modified by gtsyellow, 7:15 PM 12/7/2002]
[Modified by gtsyellow, 7:15 PM 12/7/2002]
Thread Starter
Race Director
Joined: Feb 2001
Posts: 13,913
Likes: 101
From: Manassas VA
NoVa Events Coordinator
St. Jude Donor '14
Re: Blue glow around spark plug wires (LPDesRoche)
LPDesRoche: Grab ahold of it.. :rolleyes: funny man!! Maybe you should drive up here and show me how thats done.
gtsyellow: Thanks. I have never heard of Spark leak before. I've seen arching from wires before and thats not what I see in my case. I'm not saying what i'm seeing isn't arching either. I'll do some searching on spark leak on the net and see what I can find. Yes, the wires are somewhat dirty. thanks again
[Modified by Bluewasp, 12:12 AM 12/8/2002]
[Modified by Bluewasp, 12:13 AM 12/8/2002]
[Modified by Bluewasp, 12:13 AM 12/8/2002]
gtsyellow: Thanks. I have never heard of Spark leak before. I've seen arching from wires before and thats not what I see in my case. I'm not saying what i'm seeing isn't arching either. I'll do some searching on spark leak on the net and see what I can find. Yes, the wires are somewhat dirty. thanks again
[Modified by Bluewasp, 12:12 AM 12/8/2002]
[Modified by Bluewasp, 12:13 AM 12/8/2002]
[Modified by Bluewasp, 12:13 AM 12/8/2002]
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Blue glow around spark plug wires (Bluewasp)
You might be seeing "corona" which is ionized air that occurs around wires with very high voltage. If you have bad plug wire insulation, you will see a definite spark and you will hear it. Corona will not cause a misfire, but sparking through a weak spot (usually caused by microscopic pinholes in the insulation) will cause a miss since the spark did not occur across the spark plug gap. You might also be seeing "electroluminescence" which is light generated by the spark plug insulator by the short duration high voltage pulse from the distributor. Electroluminescence will not cause a misfire either.
[Modified by jfb, 11:42 PM 12/7/2002]
[Modified by jfb, 11:42 PM 12/7/2002]
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
Re: Blue glow around spark plug wires (Bluewasp)
You say you only see the blue glow at the spark plug, not along the length of the wire, so I would concentrate on the connection at the spark plug.
If you haven't I would lubricate the inside of the connector, boot, with some silicone grease. Be sure the electrical connection is tight, that is the metal parts. Also be sure the porcelain surface of the plug is clean.
The blue glow is a good description of a phenomena called Corona, which could more or less be described as ionization of the air around a high voltage wire.
You might also verify each wire by taking a resistance measurement of each wire. The connection between the wire and its connector is somewhat fragile and could be damaged.
A great way to check wires is to look at them in the dark. It is scary what you see some times. But wires that are in great shape should be corona & spark free in the dark.
One last thought, if the plug gaps are set too high or if you are using the plus4, you might be putting too high a voltage on these plug wires.
If you haven't I would lubricate the inside of the connector, boot, with some silicone grease. Be sure the electrical connection is tight, that is the metal parts. Also be sure the porcelain surface of the plug is clean.
The blue glow is a good description of a phenomena called Corona, which could more or less be described as ionization of the air around a high voltage wire.
You might also verify each wire by taking a resistance measurement of each wire. The connection between the wire and its connector is somewhat fragile and could be damaged.
A great way to check wires is to look at them in the dark. It is scary what you see some times. But wires that are in great shape should be corona & spark free in the dark.
One last thought, if the plug gaps are set too high or if you are using the plus4, you might be putting too high a voltage on these plug wires.
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Michael S. Palmer
Le Mans Master
Joined: Feb 2002
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Re: Blue glow around spark plug wires (jfb)
You might be seeing "corona" which is ionized air that occurs around wires with very high voltage. If you have bad plug wire insulation, you will see a definite spark and you will hear it. Corona will not cause a misfire, but sparking through a weak spot (usually caused by microscopic pinholes in the insulation) will cause a miss since the spark did not occur across the spark plug gap. You might also be seeing "electroluminescence" which is light generated by the spark plug insulator by the short duration high voltage pulse from the distributor. Electroluminescence will not cause a misfire either.
[Modified by jfb, 11:42 PM 12/7/2002]
[Modified by jfb, 11:42 PM 12/7/2002]
Sounds like Corona effect. I get it to, only mine runs smooth. Very faint blue flash of light, sort of a muffled flash up near the plug. Can't really see it direct but looks like the bright metal of the plug base and the head pick it up and diffuse the light from it. Normal phenomenon w/ high energy elctronic ignition systems. :yesnod: Only noticeable in pitch dark w/ engine running at operating temp.
True arcing from bad wires or boots would be more noticeable.
[Modified by Lone Ranger, 4:34 PM 12/8/2002]
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
Re: Blue glow around spark plug wires (Lone Ranger)
I agree that most likely the wires & boots are ok, and also that seeing some corona is pretty typical. However a litte silicone on the boots would do two things. 1)It provides lubrication and moisture sealant and 2) It fills the air space around the top of the plug with a high dielectric material that is much more resistant to corona than air. Corona may not cause missing in the short term, but it does represent a drain of spark electrical energy which may or may not be important. In the long run corona will reduce the life of the wire insulation.
