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when to change spark plug wires

B

bxd20

CEG'er
Joined
Jun 25, 2000
Messages
110
Location
Cleveland, OH, USA
I know the book answer to "when do you change spark plug wires" but I'm not sure what the practical answer is.

On other cars, when I've changed wires, I've never gotten a performance gain or improved idle that I could tell. If the wires were in good physical shape and had not been tugged on or pinched.

I am at 114000 miles on my 99 SVT and am going to change the plugs very soon for the second time. I've been gentle with the wires on the previous spark plug change.

I did a spray test (wetted the wires) and the engine ran great, the rubber is in great shape.

So - convince me why I should bother changing them. :) Wire doesn't wear out by use.
 
I got the car (00 SVT) with 45K on it. I changed the plugs/wires at 70k. I've got about 125k on it now with no issues. If it's still around, I'll probably do them at about 140k.
 
I changed mine when I got tired of the gray factory wires and decided I needed red ones. The old ones are fine and I have retained them as spares. They had about 150,000 miles on them when I changed them.

One of the biggest causes of wires going bad is allowing the plugs to get badly worn, creating the need for a higher voltage to fire the plugs. Changes the plugs often enough and handle them carefully and the wire could last indefinitely.
 
That's what I was thinking Big Jim.

Thanks for the confirmation. If the plug change goes smoothly and the wires don't suffer much stress during the process I'll keep them.
 
I bought my SVT at 72K, dont know if they were changed before that. I went to have them changed a few weeks ago at 114k and they were in near perfect condition, guess it depends from driver to driver.
 
My mechanic changed my original wires at 210,000 miles, but I didn't see any improvment afterwards. Now with another 70,000 miles on the "new" wires, he's recommending changing them along with the plugs. If the original set lasted 210,000 miles, I don't see why the second Motorcraft set shouldn't last just as long. Seems to me he's trying to maximize his profit. I'm also questioning changing the plugs at 75,000 miles, as Ford says the double plats should last for 100,000 miles.
 
Since starting this thread, I've done my plugs. I handled the wires carefully and they are still in great shape, no need to replace them.

The plugs had around 60k miles on them. I am glad I replaced them. Some of the gaps were increasing to close to 0.070". The platinum buttons were getting paper thin on two of the plugs.

I have a track day coming up so it was the logical time to do them. For street driving I could have probably waited another 10k miles.

I would say double plats = change them around 70k if there are no signs of problems. I drive fairly aggressively every day.
 
theres 1998 SE wires on my svt.. car has been fine sine i got it but I just now noticed..

Theres nothing to pretty much worry about right? They look almost new lolll.. Anyway u think that would cause bad gas mileage etc? I was about to just buy plugs but when I looked at the wires, 1998 SE.. :eek: So im gonna buy wires anyway just cause.. u think thats the right way to go? or just leave them?
 
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