Spark Plug Wires

Written by Jeremy Horelick
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Spark plug wires may be small, but they factor critically into the workings of the internal combustion engine. It is the wires that conduct the electrical currents needed to ignite the fuel that's compressed inside the engine's chamber. A bad spark plug wire can lead to poor "timing," which itself can result in less efficient engines.

To derive the most power from combustion, ignition must be synched with the beginning of the combustion stroke in a four-stroke engine. This is the point at which the most pressure is built up inside the cylinder as a result of compression (the second of the four strokes). At this moment, the gases inside the chamber are compressed and ready to explode, thereby delivering power to the axles and wheels.

How the Spark Plug Wire Factors In

The importance of the spark plug wire is in conducting the spark at the precise moment that compression ends and combustion begins. A frayed, damaged, or dead wire cannot transmit the current needed to drive the "power" stroke, which can mean huge inefficiencies all around. The spark "advance" required to accommodate faster-moving pistons (a result of simple driver acceleration) is impossible, meaning that ideal temperature and pressure inside the chamber are similarly impossible.

With good spark plug wires in place, mechanics can adjust the timing of their sparks, either by advancing or delaying them. Why would someone voluntarily retard his or her spark timing? As any autoworker will tell you, doing so cuts down on engine emissions, which is not only more efficient, but more ecologically conscious as well. This, however, is impossible without healthy spark plug wires.


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