I've had my plugs replaced a few times, but haven't done anything with the plug wires. The insulation still appears to be in good shape, so I have a hard time believing that they need to be replaced at a certain mileage interval if there are no visible issues. What do ya'll think? I'm at about 156k miles now. Thanks.

Matt

 

I have always heard to replace them around 60k. That much electrical activity can break down the conductor over time and increase resistance and reduce spark. Some schools of thought believe 3-4 years in high temp areas of the country.

Just my 2 cents.

 

It gets hot under the hood which breaks down rubber. Changing the wires at around 60k is cheap insurance.

 

Dang. One more think I need to add to my 60k maint list

 

spray them with water, and look for little sparks. IF you see them you should definately replace your wires.

 

The dealer in town told me that they almost never replace them. Since when didn't a dealer NOT try to sell you something? Some folks say they will last the life of your truck, whatever that means. I sprayed a fine mist of water on the wites at night and didn't see any sparks. I wonder about the resistance question also.

'99 Limited 186,000 miles.

 

Just disconnect the wires, and measure the resistance with an ohm-meter. The maximum resistance of each wire is 25 kilo-ohm for my 2002. It should be the same for anyone with a 3.4L.

 

Ditto, plus checking for insulation breakdown via the water test or some other, more sophisticated type of an insulation resistance test. No sense replacing them if they aren't bad. Cmon, guys....

 

lol toyota makes such good parts my sparkplugs wires had 128k miles on them i think the plugs may of been changed once it still ran great just figured it was time for a tune up used factory denso plugs and got a set of ngk wires

 

Run them until your engine starts missing... that's what I've done. When a cylinder isn't firing, it's usually time for new wires.

 

when you do change them becarefull with the clips that hold it on to the coils mine where a little brittle and i broke 2 of them

 

Elton: I broke one of mine also, where did you get a replacement? Right now I have it zip tied on.

 

the dealer there not that cheap like 3 bucks each

 

Great, thanks!

 

I ran mine until May of this year when my 97 started missing. At that point we were probably at about 150,000. They looked like they'd never been replaced. Changed plugs at the same time they had about 40,000 on them.

 

Mine are still the originals at over 140k miles. As a mechanic we used to suggest changing them every 6 years regardless of mileage (the year the wires are made are usually stamped on the wire jacket), but I've found the Toyota wires to age much better than other makes. If I start getting a miss (not related to the plugs) or resistance goes beyond spec, I'll probably replace them, but until then, I'll keep running them as is.