VIDEO: ASE G1 Test Prep - Misting Spark Plug Wires
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VIDEO: ASE G1 Test Prep – Misting Spark Plug Wires

The condition of spark plug wires can affect engine operation. This video is sponsored by Autolite.

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Technician A states that lightly misting spark plug wires with water while the engine is running can help diagnose faulty spark plug wires.

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Technician B states that the length of the spark plug wire will not affect the resistance readings when it is ohm tested with a DVOM.

Who is correct?

Technician A is correct. While the engine is running, you can take a spray bottle and lightly mist water on the wires which will normally make the engine idle rough if there is leakage in the insulation. A visible spark may be noticed and an audible tick or snapping type noise may be heard as the voltage arcs out the insulation when it contacts the water.

Technician B is incorrect because most domestic vehicles use spark plug wires with a fiberglass core which provides between 10,000 and 12,000 ohms of resistance per foo tof wire, while some import models like Nissan, Honda and Toyota use spiral-wound stainless steel mag wires with approximately 500 ohms of resistance per foot of wire. But the key is understanding that the specs are per foot as they will increase with the length of the spark plug wire.

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Check the resistance specifications in the service manual for the particular vehicle you are servicing.

This video is sponsored by Autolite.

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