E.C.C.S. Components

COMPONENTS

E.C.U. (E.C.C.S. control unit)





The E.C.U. consists of a microcomputer, inspection lamps and a diagnostic mode selector for signal input and output, and for power supply. The unit has control of the following functions.

^ Injected fuel amount
^ Mixture ratio feedback
^ Ignition timing
^ Spark plug switching
^ Idle speed
^ E.G.R. operation
^ A.I.V. operation
^ Fuel pressure regulator operation
^ Fuel pump operation
^ Air regulator operation
^ Self-diagnosis

Crank Angle Sensor





The crank angle sensor is a basic component of the entire E.C.C.S. It monitors engine speed and piston position, and sends to the E.C.U. signals on which the controls of fuel injection, ignition timing and other functions are based.








The crank angle sensor has a rotor plate and a wave forming circuit. The rotor plate has 360 slits for 1° signal (crank angle signal) and 4 slits for 180° signal (engine speed signal). Light Emitting Diodes (L.E.D.) and Photo Diodes are built in the wave forming circuit. When the rotor plate passes the space between the L.E.D. and the Photo Diode, the slits of the rotor plate continually cut the light which is sent to the photo diode from the L.E.D. This causes generating rough-shaped pulses. They are then converted into on-off pulses by the wave forming circuit, which are sent to the E.C.U.





Air Flow Meter

The air flow meter measures the quantity of intake air, and sends a signal to the E.C.U. The air flow meter is provided with a flap in the air passage. During idling operation when the amount of intake air is extremely small, the air flows parallel with the flap through the by-pass port so that the specified intake air flow can be provided correctly. An air temperature sensor is installed in the air passage. The by-pass port has the air by-pass screw which regulates the idle mixture ratio. The air by-pass screw is preset and sealed at the factory.





Air Temperature Sensor

The air temperature sensor transmits an air temperature signal to the E.C.U..





Water Temperature Sensor

The water temperature sensor, built into the water outlet, monitors changes in coolant temperature and transmits a signal to the E.C.U. The temperature sensing unit employs a thermistor which is sensitive to the change in temperature. Electrical resistance of the thermistor decreases in response to the temperature rise.





Exhaust Gas Sensor

The exhaust gas sensor, which is built into the exhaust manifold, monitors the density of oxygen in the exhaust gas. It consists of a closed-end tube made of ceramic zirconia and other components. Porous platinum electrodes cover the tubes inner and outer surfaces. The closed-end of the tube is exposed to the exhaust gas in the exhaust manifold. The outer surface of the tube contacts the exhaust gas while the inner surface contacts the air.





Vehicle Speed Sensor

The vehicle speed sensor provides a vehicle speed signal to the E.C.U The speed sensor consists of a reed switch, which is installed in the speed meter unit and transforms vehicle speed into a pulse signal.





Throttle Valve Switch

The throttle valve switch is attached to the throttle chamber and actuates in response to accelerator pedal movement. This switch has idle contact and full throttle contact. The idle contact closes when the throttle valve is positioned at idle and opens when it is at any other position. The full throttle contact closes when the throttle valve is positioned at full throttle and opens when it is at any other position.





Idle Air Adjusting (I.A.A.) Unit

The I.A.A. unit is made up of the A.A.C. valve, F.I.C.D., vacuum control valve and idle speed adjusting screw. It receives the signal from the E.C.U. and controls the idle speed at the preset value.





Auxiliary Air Control (A.A.C.) Valve

The E.C.U. actuates the A.A.C. valve by an ON/OFF pulse. The longer that ON duty is left on, the larger the amount of air that will flow through the A.A.C. valve.





Vacuum Control Valve

The vacuum control valve is provided to reduce the engine lubricating oil consumption when the intake manifold vacuum increases to a very high level during deceleration. The vacuum control valve senses the manifold vacuum. As the manifold vacuum increases beyond the specified value, the valve opens and air is sucked into the intake manifold.





Air Regulator

Air regulator provides an air by-pass when the engine is cold to create a fast idle during warm-up. A bimetal, heater and rotary shutter are built into the air regulator. When the bimetal temperature is low, the air by-pass port is open. As the engine starts and electric current flows through a heater, the bimetal begins to rotate the shutter to close off the by-pass port. The air passage remains closed until the engine is stopped and the bimetal temperature drops.





Fuel Injector

The fuel injector is a small, precision solenoid valve. As the E.C.U. outputs an injection signal to each fuel injector, the coil built into the injector pulls the needle valve back, and fuel is injected through the nozzle to intake manifold. The amount of fuel injected is controlled by the E.C.U. as an injection pulse duration.





Pressure Regulator

The pressure regulator maintains the fuel pressure at 250.1 kPa (2.55 kg/cm2, 36.3 psi). Since the injected fuel amount depends on injection pulse duration, it is necessary to maintain the pressure at the above value.





Fuel Pump

The fuel pump with a fuel damper is an in-tank type, that is the pump and damper are located in the fuel tank. The vane rollers are directly coupled to a motor which is cooled by fuel.





Fuel Filter

The fuel filter is designed for the fuel injection system, and has a metal case in order to endure the high pressure of fuel.





Power Transistor

The ignition signal from the E.C.U. is amplified by the power transistor, which turns the ignition coil primary circuit on and off, inducing the proper high voltage in the secondary circuit.





Ignition Coil

The ignition coil is a small, molded type.





A.I.V. Control Solenoid Valve

This three-port solenoid valve controls the A.l.V. vacuum line based on signals supplied by the E.C.U.





E.G.R. Control Solenoid Valve

This two-port solenoid valve controls the B.P.T. vacuum line, based on signals supplied by the E.C.U.

Fuel Pressure Regulator Control Solenoid Valve

This solenoid valve is the same type as that of E.G.R. This controls the fuel pressure regulator vacuum line, based on signals supplied by the E.C.U.





Exhaust Gas Temperature Sensor (California model only)

The exhaust gas temperature sensor, built into the E.G.R. passage, measures the temperature of the inside of E.G.R. passage and transmits a signal to the E.C.C.S. control unit. The temperature sensing unit employs a thermistor which is sensitive to change in temperature. The thermistor's electrical resistance decreases in response to temperature rise.