System Outline
The engine control system utilizes a microcomputer and maintains overall control of the engine, transaxle etc. An outline of the system is given here.
- Input Signals
- Engine coolant temp. signal circuit
The engine coolant temp. sensor detects the engine coolant temperature and has a built-in thermistor that's resistance varies according to the engine coolant temperature. The engine coolant temperature is then sent to TERMINAL THW of the engine control module as a control signal.
- Intake air temp. signal circuit
The intake air temp. 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.
- Oxygen density signal circuit
The oxygen density in the exhaust emissions is detected by the heated oxygen sensor and sent as a control signal to TERMINAL OX1B of the engine control module.
- RPM signal circuit
The camshaft and crankshaft positions are detected by the camshaft position sensor and crankshaft position sensor. The camshaft position is sent as a control signal to TERMINAL G2+ of the engine control module, and engine RPM is sent into TERMINAL NE+.
- Throttle position signal circuit
The throttle body assembly detects the throttle valve opening angle and sends it as a control signal to TERMINALS VTA1 and VTA2 of the engine control module.
- Vehicle speed circuit
The speed sensors detect the vehicle speed and send it to the skid control ECU with actuator, which sends it to TERMINAL SPD of the engine control module via the combination meter.
- Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the engine control module. When the ignition SW is turned on, the voltage for the engine control module start-up power supply is applied to TERMINALS +B and +B2 of the engine control module via the EFI relay.
- Stop lamp SW signal circuit
The stop lamp SW is used to detect whether the vehicle is braking or not and the signal is sent to TERMINAL STP of the engine control module as a control signal.
- Starter signal circuit
To confirm whether the engine is cranking, the voltage that is being applied to the starter motor during cranking is detected and the signal is sent to TERMINAL STA of the engine control module as a control signal.
- Engine knock signal circuit
Engine knocking is detected by the knock control sensor and the signal is sent to TERMINAL KNK1 as a control signal.
- Air fuel ratio signal system
The air fuel ratio is detected and sent as a control signal to TERMINAL A1A+ of the engine control module.
- Engine coolant temp. signal circuit
- Control System
* SFI system
The SFI system monitors the engine condition through the signals received from each sensor by the engine control module. And a control signal is output from TERMINALS #1, #2, #3 and #4 of the engine control module to operate the fuel injector (Inject the fuel). The SFI system uses the engine control module to control the fuel injection operation in response to the driving conditions.
* ESA system
The ESA system monitors the engine conditions through the signals received by the engine control module from each sensor. The best ignition timing is decided according to this data. Then the data stored in the engine control module and the control signals are output from TERMINALS IGT1, IGT2, IGT3, IGT4. These signals control the ignition coils (Igniter) to provide the best ignition timing for the driving conditions.
* Heated oxygen sensor heater control system
The heated oxygen sensor heater control system turns the heater on when the intake air volume is low (Temp. of exhaust emissions is low), and warms up the heated oxygen sensor to improve detection performance of the sensor. The engine control module evaluates the signals from each sensor, and outputs current to TERMINAL HT1B to control the heater.
- Diagnosis System
Via 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 check engine warning 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.