W/O ESC

The Spark Control Computer is the heart of the entire system. It gives the capability of igniting the fuel mixture according to different modes of engine operation by delivering an infinite amount of variable advance curves. During cranking, an electrical signal from the distributor is fed into the computer. This signal will cause the computer to fire the spark plugs with a fixed amount of advance. Once the engine starts, then timing will now be controlled by the computer based on the information received from the various sensors.
The amount of spark advance is determined by three factors: coolant temperature, engine speed and manifold vacuum. The computer determines spark advance in the following manner:
1. Coolant temperature modifies the vacuum advance schedule. There is a different schedule for hot and for cold engines.
2. Advance from vacuum is programmed into the computer. In a cold or warm engine, vacuum advance depends only on the amount of manifold vacuum. In a hot engine, vacuum advance depends on both manifold vacuum and engine speed.
3. Advance from speed is programmed into the computer and depends only on engine speed.