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As mentioned earlier, there are three spark plug wires types: distributed resistance, inductance (MAG), and fixed resistor. Many American vehicles use distributed resistance spark plug wires. They’re made with fine strands of fiberglass impregnated with carbon. The carbon core creates very high resistance. Carmakers rely on that high resistance to reduce radio frequency interference (RFI) “noise” generated by normal ignition system operation. RFI not only ruins radio reception, but in severe cases it can interfere with the sensors and computers used to control the engine. That’s why it’s so important to buy the best spark plug wires you can afford. If your vehicle came equipped with distributed resistance wires, replace them with the same type.
Japanese manufacturers like Honda, Acura, Toyota, and Lexus prefer inductance (MAG) style spark plug wires. MAG wires are made from a spiral wound core of copper/nickel alloy wire. The spiral winding creates a magnetic field that reduces RFI. MAG wires also have less electrical resistance, so they need less current to fire the spark plug. If your automotive ignition system was designed for MAG wires, you must use buy a set of premium spark plug wires of the same type when it’s time to replace them. Don’t install low resistance MAG wires on a vehicle designed for high resistance wires.
Finally, some European cars use fixed resistor spark plug wires. These wires are made with steel or copper wire and include a resistor inside the spark plug boot. Once again, if you vehicle came with this style spark plug wire, replace them with premium spark plug wires of the same type.