System Outline

The Engine Control system utilizes a Microcomputer and maintains overall Control of the Engine, transmission, etc, an outline of the Engine Control is given here.

1. INPUT SIGNALS
1. Engine coolant temp. (water temp.) Signal Circuit
The Engine coolant temp. sensor (water temp. sensor) detects the Engine coolant temp. (water temp.) and has a built-in Thermistor with a Resistance which varies according to the Engine coolant temp. (water temp.) is input into TERMINAL THW of the Engine Control Module (Engine ECU) as a Control Signal.
2. Intake air temp. Signal Circuit
The intake air temp. sensor is installed in the volume air flow (air flow meter) and detects the intake air temp., which is input as a Control Signal to TERMINAL THA of the Engine Control Module (Engine ECU).
3. Oxygen density signal circuit
The Oxygen Density in the exhaust emission is detected and input as a Control Signal from the heated Oxygen sensor main (Oxygen sensor main (for left and right bank)) to TERMINALS OXL1, OXR1 of the Engine Control Module (Engine ECU) and from the heated Oxygen sensor sub (Oxygen sensor sub (for left and right bank) to TERMINAL OXL2, OXR2 of the Engine Control Module (Engine ECU)
To stabilize detection performance by the heated Oxygen sensor (Oxygen sensor). the heated Oxygen sensor (Oxygen sensor) is warmed.
4. RPM signal circuit
Camshaft position is detected by the Camshaft position sensor (for left and right bank) and it's Signal is input to TERMINALS G1,G2 of the Engine Control Module (Engine ECU) as a Control Signal. Also, the Engine speed 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 (Engine ECU) as a Control Signal.
5. Throttle position 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 (Engine ECU). When the valve is completely closed, the Control Signal is input into TERMINAL IDL1.
6. Vehicle speed circuit
The vehicle speed is detected by vehicle speed sensor (speed sensor) no. installed in the Transmission and the Signal is input to TERMINAL SPD of the Engine Control Module (Engine ECU) via the combination meter.
7. Neutral position signal circuit
The Park/Neutral position SW (neutral start SW) detects whether the shift position is in "N" and "P" or not, and the Signal is input into TERMINAL NSW of the Engine Control Module (Engine ECU).
8. A/C SW signal circuit
The Operating Voltage of the A/C Magnetic Clutch is detected and the Signal is input into TERMINAL ACMG of the Engine Control Module (Engine ECU) as a Control signal.
9. Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the Engine Control Module (Engine ECU) . With the Ignition SW turned on, the Voltage for Engine Control Module (Engine ECU) start-up power supply is applied to TERMINALS +B of Engine Control Module (Engine ECU) via MFI (EFI) main relay.
The Current flowing through the IGN fuse flows to TERMINAL IGSW of the Engine Control Module (Engine ECU).
10. Intake air volume signal circuit
Intake air Volume is detected by the Volume air flow(air flow meter) and the Signal is input to TERMINAL KS of the Engine Control Module (Engine ECU) as a Control Signal.
11. Stop light SW signal circuit
The stop Light SW is used to detect whether or not the Vehicle is braking and the Signal is input into TERMINAL BK of the Engine Control Module (Engine ECU) as a Control Signal.
12. 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 (Engine ECU) as a Control Signal.
13. Engine knock signal circuit
Engine knocking is detected by knock sensor NO.1 and NO.2 and the Signal is input into TERMINALS KNK1 and KNK2 as a Control Signal.

2. CONTROL SYSTEM
^ Multiport Fuel Injection (Electronically Fuel Injection system
The Multiport Fuel Injection (Electronically Fuel Injection) system monitors the Engine condition through the Signals input from each Sensor (Input Signals from (1) to (13) etc.) to the ECU. The best Fuel Injection timing is decided based on this data and the program memorized by the Engine Control module (Engine ECU) , and the Control Signal is output to TERMINALS #10, #20, #30 and #40 of the Engine Control module (Engine ECU) to operate the Injector. (Inject the Fuel). The Multiport Fuel Injection (Electronically Fuel Injection) system produces Control of Fuel Injection operation by the Engine Control module (Engine ECU) in response to the driving conditions.

^ ESA (Electronically Spark Advance) System
The ESA system monitors the Engine condition through the Signals input to the Engine Control module (Engine ECU) from each Sensor (input Signals from (1),(2), (4) to (13) etc.), the best Ignition timing is decided according to this data and the memorized data in the Engine Control module (Engine ECU) and the Control Signal is output to TERMINALS IGT1 and IGT2. This Signal Controls the Igniter to provide the best Ignition timing for the driving conditions.

^ Fuel Pressure up system
The Fuel Pressure up system causes the VSV (for Fuel Pressure up) to come on for high temp. starting and increased the Fuel Pressure to improve startability at high temperatures and to provide stable idling. The Engine Control module (Engine ECU) evaluates the input Signals from each Sensor ((1), (2), (4), (9) and (10) etc.), and outputs current to TERMINAL FPU of the Engine Control Module (Engine ECU) to Control the VSV.

^ Heated Oxygen Sensor (Oxygen Sensor) heater Control system
The heated Oxygen Sensor (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 Sensor (for left and right bank) to improve detection performance of the Sensor.
The Engine Control Module (Engine ECU) evaluates the Signals from each Sensor (input Signals from (1), (2), (4), (9) to (11) etc.), and outputs current to TERMINAL HTL1, HTR1 to Control the heater.

^ Idle Air Control (Idle Speed Control) System
The Idle Air Control (Idle speed Control system) (step motor type) increases the Engine speed and provides Idling 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 (Engine Signal evaluates the Signals from each Sensor (input Signals from (1), (4), (5), (8), (9), (11) etc.), outputs current to TERMINALS ISC1, ISC2, ISC3 and ISC4 to Control the Idle Air Control valve (ISC Valve).

^ EGR Control System
The EGR Control System detects the Signal from each Sensor (input Signals from (1), (4), (9), (10) etc.), and outputs Current to TERMINAL EGR1, EGR2, EGR3 and EGR4 to Control the EGR Valve.

^ Fuel Pump Control System
The Engine Control Module (Engine ECU) outputs Current to TERMINAL FPC and Controls the Fuel Pump Signal and Fuel pump drive speed in response to conditions.

3. DIAGNOSIS SYSTEM
With the Diagnosis System, when there is a malfunction in the Engine Control Module (engine ECU) Signal System, the malfunctioning System is recorded in the memory, the malfunctioning System can be found by reading the code displayed by the malfunction indicator lamp (check Engine warning light)

4. FAIL-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 (Engine ECU) memory or else stops the Engine.