Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

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Spark Plug: Description and Operation

PURPOSE
Spark plugs provide the path for secondary ignition system high voltage to flow to ground.

OPERATION
Voltage arcing between plug center and ground electrode produces the spark to ignite the air/fuel mixture.

CONSTRUCTION
Many spark plugs are made with an internal resistor, designed to reduce ignition system electrical interference with entertainment systems and computerized devices.