Ignition System - Direct Ignition System (Dis): Description

The Direct Ignition System (DIS) eliminates the need for a mechanical distributor. The DIS ignition system consists of 2 or 3 separate ignition coils, a DIS ignition module, a crankshaft position sensor, and the necessary wiring, as well as the Electronic Spark Timing (EST) portion of the Electronic Control Module (ECM).

This system utilizes the EST signal from the ECM to control spark timing. Ignition timing is controlled by the ECM by using information from the following inputs: crankshaft position, engine RPM, engine temperature, engine load (manifold pressure or vacuum), and atmospheric (barometric) pressure.

In the direct ignition system, each cylinder is paired with the cylinder that is opposite in the firing order. On the 2.0L and 2.5L engines, cylinders No. 1-4 and 2-3 are paired. On the 2.8L engine, cylinders No. 1-4, 3-6, and 2-5 are paired.

The spark occurs simultaneously in the cylinder coming up on the compression stroke and in the cylinder coming up on the exhaust stroke. The process is repeated when the cylinders reverse roles. Each cylinder pair is fired by its own ignition coil.