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Firecore plug boot arcing

Canadian1968

Canadian1968

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I have a set of Firecore spark plug wires I put on the car about 7 years ago. This spring noticed a misfire at low rpm . A bit inspection and I noticed one of the plug boots arcing over to the header.

As seen in the picture it has a pretty good Crack in the boot. I guess my only choice is to replace the boot ?

My question is why though..... the boot wasn't touching the header. And why is the spark trying to arc to the header first instead of thr plug.... could I have a fulty spark plug as well?

20230805_164949.jpg
 
The reason it arcs to the header first is because it is easier to jump that gap than to jump the plug gap under cylinder pressures from compression
 
Canadian1968 said:
My question is why though..... the boot wasn't touching the header. And why is the spark trying to arc to the header first instead of thr plug.... could I have a fulty spark plug as well?
Click to expand...
At BDC the cylinder is filled with a bunch of molecules in the air/fuel mixture. Then, all of those little molecules are crunched together to about 1/10 of the space. Now, you need alot of voltage for the spark to get through all those crunched molecules to the other side. Whereas, at normal atmosphere, the nitrogen/oxygen atmosphere poses much less resistance on the outside. Atmospheric pressure 14.7 psi at sea level. What is the cylinder pressure ?
 
I guess I should have re worded my question. Why would the boot crack like that ?

I understand once the boot was cracked , it was easier for the the spark to jump to the header. But why would the boot crack like that ? Just a product failure ? The silicone the boot was made of wasn't able to handle the heat like it was supposed to ? The boot itself still seems very pliable and I mean once its on the spark plug, the boot never moves. So it wasn't like a fatigue situation from constant wear .

It just seems like such an odd failure
 
It's exposed to constant changing heat/cool cycles. Things don't last forever, that's why there's replacement parts.
 
Canadian1968 said:
I have a set of Firecore spark plug wires I put on the car about 7 years ago. This spring noticed a misfire at low rpm . A bit inspection and I noticed one of the plug boots arcing over to the header.

As seen in the picture it has a pretty good Crack in the boot. I guess my only choice is to replace the boot ?

My question is why though..... the boot wasn't touching the header. And why is the spark trying to arc to the header first instead of thr plug.... could I have a fulty spark plug as well?

View attachment 1505328
Click to expand...
That's heat damage along with probably having a permanent bend in it when installed. Cracks are going to happen, and no manufacturer can be expected to cover that. Seven years is not bad if you had fun in those years.

I got a set of Firecore leads from Rick and they still look like the day I installed them....nearly 5 years ago.....granted the mileage done is low, but the heat build-up is way more than any of you guys experience I'll bet.

I was doing some running repairs today and with the side covers of the doghouse off.....I was getting burnt by the heat radiating out. Even the keychain was too hot to touch at one point.
 
Maybe it is the pic, but the boot seems 'fatter' where the damage is. Maybe the boot got stretched fitting it over the metal terminal, which started a crack or just weakened the boot.
 
I had the same issue years back. I got a set of wires with ceramic boots and no more problems!
 
WileERobby said:
At BDC the cylinder is filled with a bunch of molecules in the air/fuel mixture. Then, all of those little molecules are crunched together to about 1/10 of the space. Now, you need alot of voltage for the spark to get through all those crunched molecules to the other side. Whereas, at normal atmosphere, the nitrogen/oxygen atmosphere poses much less resistance on the outside. Atmospheric pressure 14.7 psi at sea level. What is the cylinder pressure ?
Click to expand...

You been hanging out with Bob Renton?

Just my Opinion.
 
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