The engine control system utilizes a microcomputer and maintains overall control of the engine, transmission etc. An outline of the engine control is given here.
1.Input Signals
(1)Water temp. signal circuit
The water temp. sensor detects the engine coolant temp. and has a builtin thermistor with a resistance, which varies according to the engine coolant temp.. The engine coolant temp. which is input into TERMINAL THW of the engine ECU as a control signal.
(2)Intake air temp. signal circuit
The intake air temp. sensor is installed in the air flow meter and detects the intake air temp. which is input as a control signal to TERMINAL THA of the engine ECU.
(3)Vehicle speed signal circuit
The vehicle speed signal is input from the speed sensor to skid control ECU with actuator, and are sent to the engine ECU through communication control.
(4)RPM signal circuit
Camshaft position and crankshaft position are detected by the camshaft position sensor and crankshaft position sensor. Camshaft position is input as a control signal to TERMINAL G2+ of the engine ECU, and engine RPM is input into TERMINAL NE+.
(5)Throttle position signal circuit
The throttle position sensor detects the throttle valve opening angle as a control signal, which is input into TERMINALS VTA1 and VTA2 of the engine ECU.
(6)Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the engine ECU. With the power SW is pushed on (Power SW type) or with the ignition SW is turned on (Ignition SW type), the voltage for engine ECU startup power supply is applied to TERMINALS +B and +B2 of the engine ECU via the EFI MAIN relay.
The current flowing through the IGN fuse flows to TERMINAL IGSW of the engine ECU.
(7)Intake air volume signal circuit
Intake air volume is detected by the air flow meter and the signal is input to TERMINAL VG of the engine ECU as a control signal.
(8)Stop lamp SW signal circuit
The stop light SW is used to detect whether the vehicle is braking or not and the signal is input into TERMINAL STP of the engine ECU as a control signal.
(9)Starter signal circuit
To confirm whether the engine is cranking, the voltage is applied to the starter motor during cranking is detected and the signal is input into TERMINAL STA of the engine ECU as a control signal.
(10)Engine knock signal circuit
Engine knocking is detected by knock sensor and the signal is input into TERMINAL KNK1 as a control signal.
(11)Air fuel ratio signal system
The air fuel ratio is detected and input as a control signal into TERMINAL A1A+ of the engine ECU.
(12)Oxygen sensor signal circuit
The oxygen density in the exhaust gases is detected and input as a control signal into TERMINAL OX1B of the engine ECU. To maintain stable detection performance by the heated oxygen sensor, a heater is used for warning the sensor. The heater is also controlled by engine ECU (O1B).
(13)Fuel cut in a collision
The system receives the collision signal from center airbag sensor assembly in the vehicle has a collision and stops the fuel pump operation on the side of the engine ECU.
2.Control System
*EFI system
The EFI system monitors the engine condition through the signals input from each sensor to the engine ECU. And the control signal is output to TERMINALS #10, #20, #30 and #40 of the engine ECU to operate the injector (Inject the fuel). The EFI system controls the fuel injection operation by the engine ECU in response to the driving conditions.
*ESA system
The ESA system monitors the engine condition through the signals input to the engine ECU from each sensor. The best ignition timing is decided according to this data and the memorized data in the engine ECU and the control signal is output to TERMINALS IGT1, IGT2, IGT3 and IGT4. This signal controls the igniter to provide the best ignition timing for the driving conditions.
3.Diagnosis System
With the diagnosis system, when there is a malfunction in the engine control module signal system, the malfunctioning system is recorded in the memory. The malfunctioning system can be found by reading the code displayed by the malfunction indicator lamp.
4.Failsafe System
When a malfunction has occurred in any system, if there is a possibility of engine trouble being caused by continued control based on the signals from that system, the failsafe system either controls the system by using data (Standard values) recorded in the engine ECU memory or else stops the engine.