Ignition System

Ignition System:

The SFI system is equipped with a capacitive ignition system consisting of four ignition coils and electronic circuitry built into an ignition discharge module mounted on the cylinder head of the engine. The ignition coils are controlled by electronic circuitry built into the discharge module which in its turn is regulated by low-level signals from the ECM.

When the engine is cranked, the system produces a spark in two cylinders simultaneously - 1 and 4 or 2 and 3 - for 10 consecutive complete combustion processes. Following this, on the basis of the ionization current flowing through the spark plugs and signals from the crankshaft position sensor, the system has sufficiently reliable information to synchronize spark generation and fuel injection so that optimum ignition timing is obtained.

To improve starting performance, the system always fires a large number of sparks in quick succession (multispark function) while the starter motor is engaged (1 0°BTDC - 6o°ATDC) when engine coolant temperature is below 000.

The crankshaft position sensor consists of a Hall Effect sensor and a field rotor flange with three slots, two of the same size and one smaller.

The two larger slots show that a pair of pistons is at TDC and the smaller slot indicates which pair it is. The crankshaft position sensor works in the same way and provides the same information as in earlier DI/APC electronic ignition systems.