Ignition System - DISTRIBUTORLESS: Operation: Notes

In the Distributorless Ignition System (DIS), engine timing and spark distribution is handled electronically with no moving parts. During basic operation, the EEC-IV processor determines the ignition timing and the DIS module determines which ignition coil to fire.

Each coil fires 2 spark plugs at the same time. Spark plugs are paired so as one fires during compression stroke, the other fires during exhaust stroke. There are 2 coils mounted together in a coil pack. Each coil pack has 2 tach wires, one for each coil. Since there are 2 plugs per cylinder, 2 coil packs are required, called "RIGHT SIDE" (mounted on right side of engine) and "LEFT SIDE" (mounted on left side of engine). See Figure. The right side plugs and coils operate continuously while left side plugs and coils operate when directed by the EEC in accordance with engine conditions.