Ignition Coil: Description and Operation

Distributorless Ignition System (DIS) Circuit:

PURPOSE
The Distributorless Ignition System (DIS) coils provide high voltage needed to jump the gap of the spark plugs and ignite the air/fuel mixture.

CONSTRUCTION
The coil pack contains multiple coils. Each coil within a coil pack contains a primary and secondary circuit.

The windings in the primary circuit is wound on a silicon steel core bobbin. The primary circuit grounds use the same ground through the DIS module.

The winding in the secondary circuit is on a segmented bobbin. The secondary winding uses smaller gauge wire and more turns than the primary circuit. The secondary high tension towers are connected in pairs.

OPERATION
The ignition coil fires two spark plugs simultaneously, one on the compression stroke and one on the exhaust stroke.

When a piston is on compression stroke, most of the ignition coil's available current jumps the gap of the spark plug (firing from the center electrode to side electrode), because the resistance is low.

When the companion piston is on exhaust stroke, the spark is wasted. Very little coil energy is wasted. The companion plug fires from the side electrode to the center electrode.