This ignition system does not use a conventional distributor and coil. It uses
a crankshaft position sensor input to the engine control module (ECM). The ECM then
determines electronic spark timing (EST) and triggers the direct ignition system ignition
coil.
This type of distributorless ignition system uses a waste spark method of spark
distribution. Each cylinder is paired with the cylinder that is opposite it, 1-4
or 2-3. The spark occurs simultaneously in the cylinder coming up on the compression
stroke and in the cylinder coming up on the exhaust stroke. The cylinder on the exhaust
stroke requires very little of the available energy to fire the spark plug. The remaining
energy is available to the spark plug in the cylinder on the compression stroke.
These systems use the EST signal from the ECM to control the electronic spark
timing. The ECM uses the following information:
• | Engine load, manifold pressure or vacuum |
• | Atmospheric, barometric, pressure |
Electronic Ignition System Ignition Coil
The electronic ignition (EI) system ignition coil provides the spark for 2 spark
plugs simultaneously. The EI system ignition coil is not serviceable and must be replaced
as an assembly.