System Outline

The engine control system utilizes a microcomputer and maintains overall control of the engine, transmission, etc. an outline of engine control is given here.

1. INPUT SIGNALS
1. Engine coolant temp. signal system
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. thus the engine coolant temp. is input in the form of a control signal to TERMINAL THW of the engine control module.
2. Intake air temp. signal system
The intake air temp. sensor detects the intake air temp., which is input as a control signal to TERMINAL THA of the engine control module.
3. Oxygen sensor signal system
The oxygen density in the exhaust emissions is detected and input as a control signal to TERMINALS OX1 and OX2 of the engine control module.
4. RPM signal system
Crankshaft position is detected by the crankshaft position sensor. Crankshaft position is input as a control signal to TERMINAL NE+ of the engine control module.
5. Throttle signal system
The throttle position sensor detects the throttle valve opening angle, which is input as a control signal to TERMINAL VTA of the engine control module, or when the valve is fully closed.
6. Vehicle speed signal system
The vehicle speed sensor detects the vehicle speed and inputs a control signal to TERMINAL SPD of the engine control module via the combination meter.
7. Park/Neutral position SW signal system
The Park/Neutral position SW detects whether the shift position is in neutral or not, and inputs a control signal to TERMINAL NSW of the engine control module.
8. A/C SW signal system
The operating voltage of the A/C magnetic clutch is detected and is input in the form of a control signal to TERMINAL ACT of the engine control module, and operation A/C idle-up VSV is detected and is input in the form of a control signal to TERMINAL AC1 of the engine control module.
9. Battery signal system
Voltage is constantly applied to TERMINAL BATT of the engine control module. When the ignition SW is turned to ON, voltage for engine control module operation is applied via the EFI relay to TERMINAL +S of the engine control module.
10. Intake air volume signal system
Intake air volume is detected by the manifold absolute pressure sensor and is input as a control signal to TERMINAL PIM of the engine control module.
11. STA signal system
To confirm that the engine is cranking, voltage applied to the starter motor during cranking is detected and is input as a control signal to TERMINAL STA of the engine control module.
12. Electrical load signal system
The signal, when systems such as the rear window defogger, headlight, etc. Which cause a high electrical burden are on, is input to TERMINAL ELS as a control signal.

2. CONTROL SYSTEM
* SFI system
The SFI 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, and #40 of the engine control module to operate the injector (Inject the fuel). The SF1 system produces control of fuel injection operation by the engine control module in response to the driving conditions.
During engine cranking (Signal input to TERMINAL STA) or for approx. 2 seconds after NE signal input, engine control module operation energizes (Point closed) the fuel pump circuit inside the circuit opening relay, causing the fuel pump to operate.

* ESA system
The ESA system monitors the engine conditions using the signals (Input signals (1 to 5, 9, 10)) input to the engine control module from each sensor. Based on this data and the program memorized in the engine control module, the most appropriate ignition timing is decided and current is output to TERMINAL IGT of the engine control module. This output controls the igniter to produce the most appropriate ignition timing for the driving conditions.

* Idle air control system
The idle air control system (Rotary solenoid type) increases the rpm and provides idling stability for fast idle-up when the engine is cold and when the idle speed has dropped due to electrical load, etc. The engine control module evaluates the signals from each sensor (Input signals (1 to 3, 5, 8,10,12)), outputs current to TERMINALS ISCC and ISCO, and controls the idle air control valve.
* EGR cut control system
The EGR cut control system controls the VSV (EGR) by evaluating the signals from each sensor input to the engine control module (Input signals (1 to 6,10)) and by sending output to TERMINAL EGR of the engine control module.
* A/C cut control system
When the vehicle suddenly accelerates from low engine speed, this system cuts off air conditioning operation for a fixed period of time in response to the vehicle speed, throttle valve opening angle and intake manifold pressure in order to maintain acceleration performance.
The engine control module receives input signals (4 to 6, 8), and outputs signals to TERMINAL ACT.

3. DIAGNOSIS SYSTEM
With the diagnosis system, when there is a malfunctioning in the engine control module signal system, the malfunction system is recorded in the memory. The malfunctioning system can then be found by reading the display (Code) of the malfunction indicator lamp.

4. FAIL-SAFE SYSTEM
When a malfunction occurs 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.