System Outline
The engine control system utilizes a microcomputer and maintains overall control of the engine, transaxle etc. An outline of the engine control system is given here.
- Input Signals
- Water temp. signal circuit
The water 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 then input into 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 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 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 then 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 sent from TERMINAL SP1 of the skid control ECU with actuator, via the combination meter, and then to TERMINAL SPD of the engine control module.
- Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the engine control module. When the power SW is pushed on, the voltage for engine control module start-up power supply is applied to TERMINAL +B and +B2 of engine control module via EFI 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 light 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 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 then input into TERMINAL STA of the engine control module as a control signal.
- Engine knock signal circuit
Engine knocking is detected by the knock control sensors, and is then 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.
- Water temp. signal circuit
- Control System
* SFI system
The SFI system monitors the engine conditions through the signals received from various sensors by the engine control module. Then control signals are is sent from the engine control module TERMINALS #10, #20, #30, #40, #50 and #60 to operate the injectors (Fuel injection). The SFI system controls the fuel injection via the engine control module in response to the driving conditions.
* ESA system
The ESA system monitors the engine conditions through the signals received from various sensors by the engine control module. The best ignition timing is then determined according to this data and the data stored in the engine control module. Control signals are then output from TERMINALS IGT1, IGT2, IGT3, IGT4, IGT5 and IGT6, and these signals control the igniters to provide the best ignition timing.
* 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 sensors to improve their detection performance. The engine control module evaluates the signals from each sensors, and outputs current to TERMINALS HT1B or HT2B to control 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 each sensor, and current is output from TERMINALS HA1A and HA2A, controlling the heaters.
* 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 level in accordance with the opening of the accelerator pedal, under all driving conditions.
* Dual VVT-i
Dual VVT-i adjusts the intake and exhaust valve timing to the most appropriate levels in accordance with 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 check engine 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.