You can do a resistance check to get an idea of whether they're broken or not. Most wires will register 5k-8kohms PER FOOT. The test I like to do is to put them on a car with a good ignition system, start it up at night, and then spray a mist of water over them and see if little lightning bolts go everywhere. If you see sparks, the wires can be considered bad. I usually change my wires every couple of years just to be on the safe side, though. People who drive with lifetime warrantied wires are sometimes missing the point: yes they are warranted against defects for as long as you own your vehicle, but that doesn't mean the wires are gonna be fine forever!
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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch
[This message has been edited by Capri306 (edited 05-12-2001).]