Fuel Injection Timing

OPERATION
Two types of systems are used - sequential multiport fuel injection system and simultaneous multi port fuel injection system.

Fuel Injection Timing - Sequential:

Sequential multiport fuel injection system
Fuel is injected into each cylinder during each engine cycle according to the firing order. This system is used when the engine is running.

Fuel Injection Timing - Simultaneous:

Simultaneous multi port fuel injection system
Fuel is injected simultaneously into all four cylinders twice each engine cycle. In other words, pulse signals of the same width are simultaneously transmitted from the ECM. The four injectors will then receive the signals two times for each engine cycle.
This system is used when the engine is being started and/or if the fail-safe system (CPU) is operating.

FUEL SHUT-OFF
Fuel to each cylinder is cut off during deceleration or operation of the engine at excessively high speeds.