System Outline
This system utilizes an engine control module and maintains overall control of the engine, transmission and so on. An outline of the engine control system is explained here.
- Input Signals
- Engine coolant temp. signal circuit
The engine coolant temp. sensor detects the engine coolant temperature and has a built-in thermistor whose resistance 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 temp. signal circuit
The inlet air temp. sensor is installed in the 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 sensor signal circuit
The oxygen density in the exhaust emissions is detected and is input as a control signal from the heated oxygen sensors to TERMINALS OX1B and OX2B of the engine control module.
- RPM signal circuit
The engine RPM is detected by the crankshaft position sensor which is installed in the cylinder block and the signal is input into TERMINAL NE+ of the engine control module as a control signal.
- Throttle position sensor 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.
- Vehicle speed circuit
The vehicle speed sensor detects the vehicle speed, and the signal is input into TERMINAL SPD of the engine control module via the combination meter, from TERMINAL SP1 of the skid control ECU with actuator.
- 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 through the EFI relay to TERMINALS +B and +B2 of the engine control module via the EFI MAIN relay.
- Intake air volume signal circuit
The intake air volume is detected by the mass air flow meter, and is input as a control signal to TERMINAL VG of the engine control module.
- Stop lamp SW signal circuit
The stop lamp SW 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 when the engine is cranking is detected, and is input into TERMINAL STA of the engine control module as a control signal.
- Engine knock signal circuit
Engine knocking is detected by the knock sensors, and is input into TERMINALS KNK1 and KNK2 of the engine control module as a control signal.
- Air fuel ratio signal circuit
The air fuel ratio is detected and input as a control signal into TERMINALS A1A+, A2A+ of the engine control module.
- Engine coolant temp. signal circuit
- Control System
* SFI system
The SFI system monitors the engine condition through signals which are received from various sensors by engine control module. The best fuel injection volume is determined based on this data and the program stored in the engine control module, and then control signals are output from TERMINALS #10, #20, #30, #40, #50 and #60 of the engine control module to operate the injectors (Inject the fuel). The SFI system controls the fuel injection operation via the engine control module in response to the driving conditions.
* ESA system
The ESA system monitors the engine condition through the signals, which are received by the engine control module from the various sensors. The best ignition timing is determined according to this data and the data stored in the engine control module, and control signals are output from TERMINALS IGT1, IGT2, IGT3, IGT4, IGT5 and IGT6. These signals control the igniters 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 (Exhaust emissions temperature is low), and warms up the heated oxygen sensor to improve the detection performance of the sensor.
The engine control module evaluates the signals from the various sensors and current is output from TERMINALS HT1B and HT2B, controlling the heater.
* Air fuel ratio sensor heater control system
The air fuel ratio sensor heater control system turns the heater on when the intake air volume is low (Exhaust emissions temperature is low), and warms up the air fuel ratio sensor to improve detection performance of the sensor.
The engine control module evaluates the signals from the various sensors and current is output from TERMINALS HA1A and HA2A, controlling the heater.
* ACIS
The ACIS includes a valve in the bulkhead separating the surge tank into two parts. This valve is opened and closed in accordance with the driving conditions to control the intake manifold length in two stages for increased engine output in all ranges from low to high speeds.
* ETCS-i
The ETCS-i optimizes the engine output according to the opening of the throttle valve under all driving conditions.
* VVT-i
The VVT-i optimizes the intake camshaft valve timing in to match the engine conditions.
- 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 on the malfunction indicator lamp.
- Fail-Safe System
When a malfunction has occurred in any system, there is a possibility of causing engine trouble due to continued control based on that system. In that case, the fail-safe system either controls the system using the data (Standard values) recorded in the engine control module memory, or else stops the engine.