Can spark wire wires bad even if resistance measured fine ?

[AC439]

Car has been running a little sluggish lately. I am thinking ignition. Currently has a set of NGK wires. Resistance measured all within normal limit. I do not see any external insulation damage. However, the set of NGK is pretty old (more than 10 years).

I could never find a general consent about spark plug wire set lifetime from searching the web. Everybody has a different opinion.

What do you guys think ?

[Fenris]

I generally change mine every time I do plugs, along with the cap and rotor - about every 30k miles or 2 years.

Resistance might be in spec, but they wear out. Also, the specs on those wires might be different than on the stock wires from factory.

[AC439]

I am going to order a set of NGK wires...

Anyway, I had nothing else better to do so I Seafoam the car today just to rule things out. But the car runs better after seafoam and I feel the pull is stronger. So after all, the sluggishness may not be electrical related.

[Dr_Snooz]

It's an interesting question. The maintenance schedule in the manual only says to inspect, not replace, the wires every 60k miles. The inspection involves a visual check of the condition of the connectors, followed by a resistance test with an ohmmeter. Of course, the maintenance schedule does not go past 100k miles, and very few 3g's have fewer than that. So what now?

With heat cycling, the insulation on the wires can degrade and allow "spark leak" at some point. That should be easy enough to discover by viewing the running engine bay in the dark. But other things can also go wrong, like the connectors loosening and not making good contact. If the wires are noticeably aged, cracked, hard or if they simply aren't giving you the warm fuzzies anymore, I'd change them.

[AC439]

Yeah, I'm a cheap skate and just want to use the wires as long as it can last. But the car did not experience any misfires, just felt sluggish overall.

Somehow, the seafoam treatment has restored power. But I'm going to order wires anyway cause its over 10 years old.

[Dr_Snooz]

I've come to a similar opinion. I used to be religious about the maintenance schedule but started to realize how much it all costs. When I started investigating the parts I was throwing away, I saw that many were still in great shape. I'm focusing more on inspecting, measuring and testing parts now before simply replacing them. It saves a lot of money.