Do ignition wires go bad with time or mileage? Should I replace?

The wires breakdown internally through the electrical current, so use rather than time would be the key. You can measure the resistence and if to spec they are fine. Maybe replace the coil wires if you want to do something proactive.

Coils are designed to last about 80,000 miles or more. Unless they were subjected to high heat, moisture etc. while in storage, they should be fine.

I would focus on the rubber parts: brake, coolant and fuel hoses. They deteriorate with time. And get new tires for sure.

 

Keep the caps and rotors and buy the wires.

Wires age. Caps and rotors don't.

 

$800 ?? You don't have to buy the ones that come in the yellow box with the horsie on it

 

Exactly what I did on my 328.

I had a 1991 Alfa spider once. Had about 120K miles on it. Replaced the wires with a cheaper aftermarket set. Car ran horrible. Bought the OEM set and it worked great. So, wires do make a difference.

 

Good day all,

Ignition wires do not breakdown because of current...in fact virtually all electrical conductors do not "wear" out do to current (unless a lot more current is used than the conductor was designed to accommodate). If so, then every single wire in your car, house, etc would need replacing over time. Ignition wires need replacement do to age and use. Age is an important factor, as the ignition wire's insulating material... the stuff that keeps the high voltage/energy from shorting to ground and instead directs the energy to the spark plug... loses its ability to properly insulate over time do to the materials used. Think of it like tires... rubber becomes hard as a rock with age, because the key components used dissipate over time.
Also, the resistance of a ignition wire is a poor indicator of its condition... as mentioned, it is the insulating quality of the wires is the most critical... which cannot be measured with typical multimeters, etc.

Age, usage (number of high voltage sparks) heat, exposure to oil/grease/water, etc are the contributing factors to the effectiveness of ignition wires. If the wires are old, just replace them...

Ignition coils are similar, but are more affected with use, but age is a factor as well. Over time the high voltage energy generated breaks down the ignition coil's internal insulator which is usually oil based. Over time this insulator allows internal energy leakage and so less energy is delivered through the secondary winding of the coil... which makes its way to the spark plug.

Cheers,

Sam

 

An easy test is to look at the engine idling with the lights out. If you see arcs, there bad. But if they have been on a while, go ahead and replce the wire. Inspect the caps. If they are clean, you are fine. If they need to be replaced, look at Superformance. They use to have more affordable parts, and most were OEM.

 

Terrible test. Keep your day job.

 

I just replaced a set of wores on a 328 on Friday. Cylinder number 1 and 8 wires were cooked so bad they would snap of you tried to bend them. They were the original set.

 

My experience: About 12 years ago my 328 would momentarily lose power (hiccup just once) while driving. Engine would seem normal after that except the engine idle would be at 1500 rpm instead of 900. Rifledriver said it was the spark plug wires. I replaced the entire set. The problem immediately vanished and never returned.

 

Wores??? Great joke there but I just cant. Canukistan must be more liberal than I realized.

 

Lol..obviously "wires" the "I" is beside the "O". Again, fat fingers to the rescue..

 

If the thing is not running right, (and assuming the plugs are not 30,000 miles old!) check the extenders for burn through & if not that then take the caps off & look for oil inside. Then check all the leads for continuity (starting with the connections in the caps).

As has been said a million times, they are spiral wound wires & they break internally but can continue to work for a while as the spark jumps the gap inside the wire.

Eventually the gap grows and they stop working. If its caused by anything, its likely heat related but regardess of why, they do it.

Otherwise leave well alone.

 

Engine heat kills them