Plugs & Wires

[SuperCoupe400]

What symptoms will the car (engine) display when it's time to change the plugs &/or wires. It's not that I've never changed a set of plugs & wires before. Just never in this car ('93 SC4 i've had for 2-years). With my previous car, whenever I experienced any type of mechanical problem that I couldn't trace to anything else, I'd just go ahead and throw-in a new set of plugs, and if the engine bumbling and hesitation still didn't stop I'd swap the wires too.

But I'd like to be a bit more scientific with my approach on the Lex. So what are the main symptoms of a car who's plugs &/or wires need changing?

Thanks.

[lexus082]

There should be a manufacturing year printed on the wires and that will tell you approx. the last time they were changed. Also you can test the resistance of the wire to see if they are still within oem specs. Worn spark plugs: poor fuel economy, engine to misfire, poor engine performance. You should also change distributor caps and rotors as well at the same time.

[ellwoodnorth]

60,000 - 100,000 miles is a reasonable interval. (60K if you are mainly a city driver and 100K if you are mainly a highway driver).