System Outline

The Engine control system utilizes a microcomputer and maintains overall control of the Engine. an outline of Engine control is given here.

1. INPUT SIGNALS
1. Engine Coolant Temp. (Water Temp.) Signal System
The Engine Coolant Temp. Sensor (EFI Water Temp. Sensor) detects the Engine coolant temp. and has a built-in Thermistor with a resistance which varies according to the Engine coolant temp. (water temp.) thus the Engine coolant temp. (water temp.) is input in the form of a control signal to TERMINAL THW of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).
2. Intake Air Temp. Signal System
The Intake Air Temp. Sensor is detects the intake air temp., which is input as a control signal to TERMINAL THA of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).
3. Oxygen Sensor Signal System
The oxygen density in the exhaust emissions is detects and input as a control signal to TERMINAL OX of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).
4. RPM Signal System
Crankshaft position and Engine RPM are detected by the pick-up coil installed inside the distributor. Crankshaft position and RPM are input as a control signal to TERMINALS NE and G of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).
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 (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (A/T), or when the valve is fully closed, to TERMINAL IDL.
6. Vehicle Speed Signal System
The Vehicle Speed Sensor (Speed Sensor) installed inside the Combination Meter, detects the vehicle speed and inputs a control signal to TERMINAL SPD of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T))
7. Park/Neutral position SW (Neutral Start SW) Signal System
The Park/Neutral position SW (neutral start SW) detects whether the shift position is in neutral or not, and inputs a control signal to TERMINAL NSW of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T)).
8. A/C Signal System
The operating voltage of the A/C Magnetic Clutch is detected and input in the form of a control signal to TERMINAL AC1 of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).
9. Battery Signal System
Voltage is constantly applied to TERMINAL BATT of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)). When the Ignition SW is turned to ON, voltage for Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)) operation is applied via the EFI relay to TERMINAL +B of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).
10. Intake Air Volume Signal System
Intake air volume is detected by the manifold absolute pressure sensor (Vacuum Sensor) and is input as a control signal to TERMINAL PIM of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).
11. STA Signal System
To confirm that the Engine is cranking, the voltage applied to the starter motor during cranking is detentes and is input as a control signal to TERMINAL STA of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).
12. Electrical Load Signal System
The signal when systems such as the A/C compressor ON (USA A/T), A/T shift position (N or D), electric fan (USA A/T), headlights (USA M/T) and daytime running light system (Canada) which causes a high electrical burden are ON is input to TERMINAL ELS of Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).

2. CONTROL SYSTEM
* MFI (Multiport Fuel Injection) System
The MFI (EFI) system monitors the Engine revolutions through the signals each sensor (input signals (1) to (11)) inputs to the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)). Based on this data and the program memorized in the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)), the most appropriate fuel injection timing is decided and current is output to TERMINALS #10 and #20 of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)), causing the injectors to operate (to inject fuel). It is this system which, through the work of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)), finely controls fuel injection in response to driving conditions. During Engine cranking (signal input to TERMINAL STA) or for approx. 2 seconds after ne signal input, computer operation energizes (point closed) the fuel pump circuit inside the circuit opening relay, causing the fuel pump to operate.

* EI (ESA, Electronic Spark Advance) System
The EI (ESA) system monitors the Engine revolutions using the signals (input signals (1, 4, 5, 10, 11)) input to the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)) from each sensor. Based on this data and the program memorized in the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)), the most appropriate ignition timing is decided and current is output to TERMINAL IGT of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T). This output controls the igniter to produce the most appropriate ignition timing for the driving conditions.

* Fuel Pressure Control System
The fuel pressure control system causes the VSV (fuel pressure up) to come on for high temp. starts and for about 90 seconds after starting in order to increase the fuel pressure, improve startability at high temperatures and provide stable idling. The Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)) evaluates the input signals from each sensor (input signals (1, 2, 5)), and controls the VSV (fuel pressure up).

* 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 (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)) (input signals (1, 4, 5, 10)) and by sending output to TERMINAL EGR of the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)).

* Idle Speed Control System
This system uses the VSV (idle speed control) for idle speed to increase the RPM and provide stable idling when the idle speed drops due to the electrical load, etc. the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)) evaluates the signals from each sensor (input signals (1, 4, 5, 6, 7, 8, 12)), current is output to TERMINAL DISC and controls the VSV (idle speed control).

* 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 nodule (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)) receives input signals (4, 5, 6, 7 and 10), and outputs signals to TERMINAL ACT.

3. DIAGNOSIS SYSTEM
With the diagnosis system, when there is a malfunctioning in the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T) 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 (check Engine warning light).

4. FAIL-SAFE SYSTEM
When a malfunctioning 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 date (standard valued) recorded in the Engine Control Module (Engine and Electronically Controlled Transmission ECU (A/T), Engine ECU (M/T)) memory or else stops the Engine.