Ignition System: Description and Operation

System Schematic Diagram:

PURPOSE

Ignition system supplies spark to ignite air/fuel mixture.

OPERATION

Coil steps up primary voltage (12 Volts) to secondary voltage (25,000-35,000V).

Engine controller controls coil primary current through Auto Shutdown (ASD) relay ground.
When ASD relay is grounded an electromagnetic field is generated by current in coil primary windings. When ground is removed, field collapses, inducing high voltage in secondary windings.
High voltage routed to spark plugs via distributor.

Engine controller advances or retards ignition timing to provide optimum performance [1] for all operating conditions.

NOTE: During CRANK-START engine controller provides set advance for quick, efficient starts.

CONSTRUCTION

System consists of, engine controller and inputs, ignition coil, ignition distributor, secondary ignition cables and spark plugs.

[1] Optimum performance: best compromise between power, fuel consumption, and emissions.