System Outline
Engine Control Operation
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
- Engine coolant temperature signal circuit
The E.F.I. engine coolant temperature 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 sent to TERMINAL THW of the ECM 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 sent as a control signal to TERMINAL THA of the ECM.
- Oxygen sensor signal circuit
The oxygen density in the exhaust emissions is detected and is sent as a control signal from the oxygen sensors to TERMINALS OX1B and OX2B of the ECM.
- RPM signal circuit
The engine RPM is detected by the crankshaft position sensor installed in the cylinder block and the signal is sent to TERMINAL NE+ of the ECM as a control signal.
- Throttle position sensor signal circuit
The throttle body assembly detects the throttle valve opening angle as a control signal, which is sent to TERMINALS VTA1 and VTA2 of the ECM.
- Vehicle speed circuit
The speed sensor detects the vehicle speed, and the signal is sent from TERMINAL SP1 of the skid control ECU with actuator assembly to TERMINAL SPD of the ECM via the combination meter assembly.
- Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the ECM. When the engine switch is turn the engine switch on (IG), the voltage from the ECM startup power supply is applied to TERMINAL +B and +B2 of ECM via EFI relay.
- Intake air volume signal circuit
The intake air volume is detected by the mass air flow meter, and is sent as a control signal to TERMINAL VG of the ECM.
- Stop light switch signal circuit
The stop light switch assembly is used to detect whether the vehicle is braking or not, and the signal is sent to TERMINAL STP of the ECM as a control signal.
- Starter signal circuit
To confirm whether the engine is cranking, the voltage whish is being applied to the starter assembly when the engine is cranking is detected, and is sent to TERMINAL STA of the ECM as a control signal.
- Engine knock signal circuit
Engine knocking is detected by the knock control sensors, and is sent to TERMINALS KNK1 and KNK2 of the ECM as a control signal.
- Air fuel ratio signal circuit
The air fuel ratio is detected and sent as a control signal to TERMINALS A1A+, A2A+ of the ECM.
- 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 ECM. Control signals are sent from ECM TERMINALS #10, #20, #30, #40, #50 and #60 to operate the fuel injector assembly (Fuel injection). The SFI system controls the fuel injection for the ECM in response to the driving conditions.
* ESA system
The ESA system monitors the engine condition through the signals received from various sensors by the ECM. The best ignition timing is determined according to this data and the data stored in the ECM. Control signals are then sent from TERMINALS IGT1, IGT2, IGT3, IGT4, IGT5 and IGT6, and these signals control the ignition coil assembly (Igniter) to provide the best ignition timing.
* Oxygen sensor heater control system
The 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 oxygen sensors to improve their detection performance. The ECM evaluates the signals from each sensor and outputs current from 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 the detection performance of the sensor.
The ECM evaluates the signals from each sensor 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 in accordance with the accelerator pedal opening, under all driving conditions.
* Dual VVT-i
Dual VVT-i controls the intake and exhaust valve timing to the most appropriate levels in accordance with the ECM.
- Diagnosis System
When there is a malfunction in the ECM signal system, the malfunctioning system is recorded in the ECM 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 ECM memory, or else stops the engine.
Electronically Controlled Transmission Operation
- Line Pressure Optimal Control
Through the use of the solenoid valve SLT, the line pressure is optimized in accordance with the engine torque information, as well as with the internal operating conditions of the torque converter and the transaxle. Accordingly, the line pressure can be controlled minutely to compensate for the engine output, driving conditions, and the ATF temperature, thus allowing smoother shifting and optimizing the workload on the oil pump.
- Clutch Pressure Optimal Control
The ECM monitors the signals from various sensors such as the input transmission revolution sensor (Turbine), to allow shift solenoid valves SL1, SL2 and SL3 to minutely control the clutch pressure in accordance with the engine output and driving conditions. As a result, the shifting characteristics have become even smoother.
- Shifting Control during Uphill and Downhill Travel
This control minimizes the shifting of gears when the driver operates the accelerator pedal while driving on a winding road with ups and downs, in order to ensure a smooth drive.
- Flex Lock-Up Clutch Control
The flex lock-up clutch control operates during acceleration in the 2nd, 3rd, 4th, 5th and 6th gears in the D position, and during deceleration in the 4th, 5th and 6th gears in the D position.
- Multi Mode Automatic Transmission
The multi mode automatic transmission has an [S]-position beside the [D]-position. By moving the selector lever to the "S" side, you can select the shift range in the same method as manual shifting.
- Line Pressure Optimal Control