What Causes the Wires to Go Bad?
Spark plug wires can fail for a variety of reasons.
1) Thermal Stress
Spark plug wires are highly insulated and designed to withstand high temperatures, but because they are usually located close to the engine’s exhaust manifold, they are eventually susceptible to heat damage.
When this happens, the insulation on the spark plug wire becomes too brittle, creating a path for spark energy to transfer to ground.
2) Friction
Cables can also be damaged by friction. This occurs when your engine’s spark plug wires rub and chafe against rough or sharp edges, eventually causing a hole in the wire’s protective insulation. Similar to the example above, this newly damaged piece of insulation provides a viable path to ground for electrical energy.
This type of problem occurs especially when your engine’s ignition cable is not secured in its original holder.
3) Vibration
Prolonged exposure to vibration is also a major cause of ignition cable failure. Your vehicle’s engine is constantly shaking and vibrating, which causes fatigue in the internal filament of the ignition wire.
Over time, excessive resistance can build up in the ignition wire itself, leading to overheating and further deterioration. In severe cases, the cable’s insulation can even begin to melt.
How long do ignition cables last?
The average lifespan of a set of spark plug wires is around 60,000 to 80,000 miles, but the fact is that eventual failure of one or more spark plug wires is likely to occur sooner or later.
However, it’s important not to wait for your engine’s spark plug wires to fail, but to replace them whenever possible as preventative maintenance. This will prevent many other mechanical problems.
When damaged spark plug wires wear down to the point of failure, they can cause misfires. Over time, this condition itself can lead to poor fuel metering and complete failure of the catalytic converter, resulting in a lot of unnecessary costs.
Are ignition cables universal? Not all spark plug wires are the same. In fact, most spark plug wires are designed for the specific application for which they are intended. This makes the majority of spark plug wires far from generic in nature.
Most importantly, most spark plug wires today are designed to a specific length to perfectly fit a designated engine.
However, you can also order generic spark plug wires that need to be cut to the required length for your application. However, it takes a little more time and planning to get these cables ready for use. This type of spark plug wire is usually clearly marked “universal” on the packaging.