Engine and Emission Control System Description - Fuel Injection Control (Cont'd)

Two types of fuel injection systems are used - simultaneous injection and sequential injection. In the former, fuel is injected into all four cylinders simultaneously twice each engine cycle. In other words, pulse signals of the same width are simultaneously transmitted from the E.C.U. to the four injectors two times for each engine cycle. In the sequential injection system, fuel is injected into each cylinder during each engine cycle according to the firing order. When the engine is being started and/or if the fail-safe system (C.P.U. of E.C.U.) is operating, simultaneous fuel injection is used. When the engine is running sequential fuel injection is used.

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