System Outline
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.
- Input Signals
- Engine coolant temperature signal circuit
The engine coolant temperature sensor detects the engine coolant temperature and has a built-in thermistor with a resistance which varies according to the engine coolant temperature. The engine coolant temperature is input into TERMINAL THW of the engine control module as a control signal.
- Intake air temperature signal circuit
The intake air temperature sensor is installed in the mass air flow meter and detects the intake air temperature which is input as a control signal to TERMINAL THA of the engine control module.
- Vehicle speed signal circuit
The vehicle speed signal is input from the speed sensor to the skid control ECU with actuator, and is sent to the engine control module through communication control.
- RPM signal circuit
The engine RPM is detected by the crankshaft position sensor installed in the cylinder block and the signal is input into TERMINAL NE+ of the engine control module as a control signal.
- 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 control module.
- Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the engine control module. When the ignition Switch is turned on, the voltage for engine control module start-up power supply is applied to TERMINALS +B and +B2 of the engine control module via the EFI MAIN relay.
The current flowing through the IGN fuse flows to TERMINAL IGSW of the engine control module.
- Intake air volume signal circuit
Intake air volume is detected by the mass air flow meter and the signal is input to TERMINAL VG of the engine control module as a control signal.
- Stop light switch signal circuit
The stop light switch is used to detect whether the vehicle is braking or not and the signal is input into TERMINAL STP of the engine control module as a control signal.
- Starter signal circuit
To confirm whether the engine is cranking, the voltage which is being applied to the starter motor during cranking is detected and the signal is input into TERMINAL STA of the engine control module as a control signal.
- Engine knock signal circuit
Engine knocking is detected by knock sensor and the signal is input into TERMINAL KNK1 as a control signal.
- Air fuel ratio signal system
The air fuel ratio is detected and input as a control signal into TERMINAL A1A+ of the engine control module.
- 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 control module. 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 control module.
- Engine coolant temperature signal circuit
- Control System
* SFI system
The SFI system monitors the engine condition through the signals received from various sensors by the engine control module. And then control signals are output from TERMINALS #10, #20, #30 and #40 of the engine control module to operate the injectors (Inject the fuel). The SFI system controls the fuel injection operation for the engine control module in response to the driving conditions.
* ESA system
The ESA system monitors the engine condition through the signals received by the engine control module from various sensors. The best ignition timing is decided according to this data and the data stored in the engine control module and the control signals are output from TERMINALS IGT1, IGT2, IGT3 and IGT4. These signals control the igniters to provide the best ignition timing for the driving conditions.
- 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.
- Fail-safe 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 fail-safe system either controls the system by using data (Standard values) recorded in the engine control module memory or else stops the engine.