Engine and Emission Control Parts Description - Throttle Sensor & Soft Idle Switch (Cont'd)

The fuel injector is a miniaturized, lightweight, solenoid valve. As the E.C.U. sends injection signals to the injector, the flat valve is pulled back and fuel is released into the intake manifold with two directions of spray. The amount of fuel injected is controlled by the E.C.U. in terms of the injection pulse duration.

The pressure regulator maintains the fuel pressure at 299.1 kPa (2.991 bar, 3.05 kg/cm2, 43.4 psi). Since the injected fuel amount depends on injection pulse duration, it is necessary to maintain the pressure at the above value.

The exhaust gas sensor, located in the exhaust tube, monitors the oxygen level in the exhaust gas. This sensor is made of zirconia, the electric resistance of which drastically changes at the ideal air-fuel ratio. The E.C.U. supplies the sensor with approximately 1V and then measures the output voltage depending on its resistance. In order to activate the sensor element, it is equipped with a heater (13W).