Computer Controlled Coil Ignition (C3I)

The Computer-Controlled Coil Ignition (C3I) System is an Electronic Spark Timing (EST) system which consists of an Electronic Control Module (ECM), ignition (coil) module, electro-magnetic camshaft and crankshaft position sensors and necessary wiring, Figs. 1-11.
The ignition (coil) module replaces the conventional ignition coil and distributor and has an integral microprocessor which receives and buffers information from the crankshaft and camshaft position sensors to determine the proper firing sequence, then selects and triggers each of the three inter-connected coils to fire the spark plugs.
The three inter-connected coils must fire two spark plugs simultaneously. Therefore, Cylinder Nos. one and four, five and two and three and six are selected for each coil. When cylinder No. one is approaching TDC on the compression stroke, cylinder No. 4 is on the exhaust stroke, and so on through the entire spark plug firing sequence. Very little energy is required to fire the spark plug in the cylinder on the exhaust stroke, so the remaining high voltage is used to fire the spark plug in the cylinder on the compression stoke.
Ignition timing is determined by the Electronic Control Module (ECM) which monitors crankshaft position, engine RPM, engine temperature and amount of air the engine is consuming, then signals the ignition (coil) module accordingly. Electronic Spark Control (ESC) is also used to retard timing during times of spark detonation. The ESC system is comprised of a knock sensor and an ESC module, Figs. 12-14. As the knock sensor detects detonation, the ESC module to ECM voltage is shut off, signalling the ECM to retard the spark. An electronic filter is used to filter out vibrations not related to detonation.