Fuel Injection Control

System Diagram:

FUEL INJECTION SYSTEM
PURPOSE
The fuel injection system maintains the correct air/fuel ratio by constantly adjusting the fuel delivery rate according to sensor inputs.

CONSTRUCTION
The fuel injection system is of electronically controlled type and consists of the Engine Control Module (ECM), Electric Fuel Pump, Fuel Pressure Control Vacuum Switching Valve (VSV), Mass Air Flow Sensor, Fuel Injectors, Crankshaft Position Sensor (built into Distributor), Engine Coolant Temperature Sensor and others.

Fuel Injection Control:

OPERATION
The pressure of the fuel delivered from the fuel pump is controlled at the end of the fuel rail, so that it can keep a certain amount of pressure differential over the intake manifold pressure.

This is accomplished by the pressure regulator of overflow type.

The volume of the fuel to be injected, therefore, changes depending on the opening duration of the injector valves.

Regarding the air to be drawn into the engine, its mass flow is sensed by the mass air flow sensor of hot wire type. This sensor generates voltage corresponding to the mass flow of the air drawn into the engine.

The changing voltage is transformed into an electric signal and provided to the ECM.

With receipt of the signals sent from the mass air flow sensor and others, the ECM determines an appropriate fuel injection pulse width referring to the programmed data thereof, feeding such information to the fuel injector valves to effect an appropriate air/fuel ratio.