Computers and Control Systems: Description and Operation

This system utilizes an engine control module and maintains overall control of the engine, transaxle and so on. An outline of the engine control is explained here.

1. INPUT SIGNALS
1. Engine coolant temp. signal circuit
The engine coolant temp. sensor detects the engine coolant temp. and has a built-in thermistor with a resistance which varies according to the engine coolant temp. input into TERMINAL THW of the engine control module as a control signal.

2. Intake air temp. signal circuit
The intake air temp. sensor is installed in the mass air flow meter and detects the intake air temp., which is input as a control signal into TERMINAL THA of the engine control module.

3. Oxygen sensor signal system
the oxygen density in the exhaust gases is detected and input as a control signal into TERMINALS OXL1, OXR1 and OXS of the engine control module. To maintain stable detection performance by the oxygen sensor, a heater is used to warm the sensor. The heater is also controlled by the engine control module (HTL, HTR and HTS).

4. RPM signal system
Camshaft position and crankshaft position are detected by the camshaft position sensor and crankshaft position sensor Camshaft position is input as a control signal to TERMINAL G22+ of the engine control module, and engine RPM is input into TERMINAL NE+.

5. Throttle signal circuit
The throttle position sensor detects the throttle valve opening angle as a control signal, which is input into TERMINAL VTA1 of the engine control module.

6. Vehicle speed signal system
The vehicle speed is detected by the ABS speed sensor, and is input into the ABS actuator and ECU. The vehicle speed signal from the ABS ECU is input into the engine control module TERMINAL SPD through the combination meter.

7. Park/Neutral position SW signal system
The Park/Neutral position SW detects whether the shift position is in neutral or parking and inputs a control signal into TERMINAL NSW of the engine control module.

8. A/C SW signal system
The A/C amplifier inputs the A/C operations into TERMINAL A/C of the engine control module as a control signal.

9. 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 engine control module stand-up power supply is applied to TERMINAL +B of engine control module via EFI relay.

10. Intake air volume signal circuit
Intake air volume is detected by the mass air flow meter, and a signal is input into TERMINAL VG of the engine control module as a control signal.

11. Starter signal circuit
To confirm whether the engine is cranking, the voltage 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.

12. Engine knock signal circuit
Engine knocking is detected by the knock sensor 1 and 2, and the signals are input into TERMINALS KNKR and KNKL as a control signal.

2. CONTROL SYSTEM
* S F1 (Sequential multiport Fuel Injection) system
The SF1 system monitors the engine condition through the signals, which are input from each sensor (Input signals from (1) to (12) etc.). The best fuel injection volume is decided based on this data and the program memorized by the engine control module, and the control signal is output to TERMINALS #10, #20, #30, #40, #50 and #60 of the engine control module to operate the injector (Inject the fuel). The SF1 system controls the fuel injection operation by the engine control module in response to the driving conditions.

* ESA (Electronic Spark Advance) system
The ESA system monitors the engine condition through the signals, which are input to the engine control module from each sensor (Input signals from (1), (3), (4) to (12) etc.). The best ignition timing is decided according to this data and the memorized data in the engine control module, and the control signal is output to TERMINALS IGT1, IGT2 and IGT3. This signal controls the 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 (Input signals from (1), (4), (9) to (10) etc.), and outputs current to TERMINALS HTL, HTR and HTS, controlling the heater.

* IAC (Idle Air Control) system
The IAC system (Rotary solenoid type) increases the RPM and provides idle stability for fast idle-up when the engine is cold, and when the idle speed has dropped due to electrical load and so on. The engine control module evaluates the signals from each sensor (Input signals from (1), (4), (5), (8), (9) etc.), and outputs current to TERMINALS RSO and RSC, controlling idle air control valve.

* ACIS (Acoustic Control Induction System)
ACIS includes a valve in the bulkhead separating the surge rank 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.

The engine control module judges the engine speed by the signals ((4), (5)) from each sensor and outputs signals to the TERMINAL ACIS to control the VSV (for opening and closing the intake control valve).

3. DIAGNOSIS SYSTEM
When there is a malfunction in the engine control module signal system, the diagnosis system records the malfunction in its memory.

4. Fall-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.