E.C.C.S. System Controls

Fuel Injection Control
The E.C.U. calculates the basic injection pulse width by processing signals from the crank angle sensor and air flow meter. Receiving signals from each sensor which detects various engine conditions, the E.C.U. adds various enrichments, which are pre-programmed in the E.C.U. to the basic injection amount. Thus, the optimum amount of fuel is injected through the Injectors.





1) Fuel enrichment:
In each of the following conditions, fuel is enriched.

^ During warm-up
^ When starting
^ After idle
^ With heavy load
^ Full throttle

Enrichment rates for "with heavy load/full throttle" is preprogrammed for engine speed and basic injection pulse width.





2) Simultaneous injection
Fuel is injected into all four cylinders simultaneously twice each engine cycle.





Spark Plug Switching Control





Fuel Pressure Regulator Control
The pressure regulator control improves hot restartability by increasing fuel pressure. When the system is in operation, the pressure regulator control solenoid valve comes on, the intake manifold vacuum is cut and atmospheric pressure is supplied to the pressure regulator, thereby increasing the fuel pressure. Pressure regulator control solenoid valve and pressure pump are controlled by E.C.U.





This system operates when following conditions are met.

^ Water temperature is above 60°C (140° F).
^ Engine speed is lower than 6,375 rpm or light load conditions exist.





Fuel Pump and Air Regulator Control





The fuel pump and air regulator ON-OFF are simultaneously controlled by the E.C.U.

Fuel Pump Voltage Control





The fuel pump is controlled by the E.C.U. ad justing the voltage supplied to the fuel pump.





Air Induction Valve (A.I.V.) Control








The air induction valve (A.I.V.) system is utilized to reduce HC and CO emissions by supplying air through the air induction valve. This system is composed of the air induction valve, the A.I.V. control valve and the A.I.V. solenoid valve. The air induction valve is designed for one-way operation and consists of one-way reed valves. It inducts the secondary air into the exhaust manifold via the exhaust pressure pulsations. The A.I.V. control valve is controlled by the A.I.V. solenoid valve which is controlled by the electrical signal from the E.C.U.





Exhaust Gas Recirculation (E.G.R.) Control





In the exhaust gas recirculation system, some of the exhaust gas is returned to the combustion chamber to lower the flame temperature during combustion. This results in a reduction of the nitrogen oxide density in the exhaust gas. When the E.G.R. control valve is open, some of the exhaust gas is led from the exhaust manifold to the E.G.R. tube. The exhaust gas is then regulated by E.G.R. valve, and is introduced into the intake manifold. The signal from the E.C.U. is sent to the E.G.R. control solenoid valve, which cuts the vacuum line for the B.P.T. valve when any of the conditions are met.





Idle Speed Control

The idle speed is controlled by the E.C.U., corresponding to the engine operating conditions. The E.C.U. senses the engine condition and determines the best idle speed at water temperature and gear position. The control unit then sends an electronic signal corresponding to the difference between the best idle speed and the actual idle speed to the A.A.C. valve. The E.C.U. controlled idle speed feedback is carried out when the following conditions are satisfied.

1) Idle switch "ON"

2) Vehicle speed is lower than 8 km/h (5 MPH).





Ignition Timing Control

Ignition timing is controlled, corresponding to the engine operating conditions, by the E.C.U. That is, as the optimum ignition timing in each driving condition has been pre-programmed in the E.C.U., the ignition timing is determined by electrical signals processed in the E.C.U. The signal from the E.C.U. is transmitted to the power transistor, and controls ignition timing.