Computers and Control Systems: Description and Operation

This system utilizes an Engine Control Module and maintains overall control of the Engine, Transmission 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 water temp. is input into TERMINAL THW of Engine Control Module as a control signal.
2. Intake Air Temp. Signal Circuit
The intake Air Temp. Sensor is installed in the volume air flow and detects the intake air temp., which is input as a control signal to TERMINAL THA of Engine Control Module
3. Oxygen Sensor Signal System
The Oxygen density in the exhaust gases is detected and input as a control signal to TERMINAL OXL, OXR and OXS of the Engine Control Module. To maintain stable detection performance by the Oxygen Sensor, a heater is used for warming the Sensor. The heater is also controlled by the by the Engine Control Module (HTL, HTR and HTS).
4. RPM Signal System
Camshaft position is detected by the Camshaft position sensor, and crankshaft is detected by the crankshaft position sensor. Camshaft position is input as a control signal to TERMINAL G22+ of the Engine Control Module, and Crankshaft position is input to 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 VTA of the Engine Control Module. When the valve is completely closed, the control signal is input into TERMINAL IDL.
6. Vehicle Speed Signal System
The Vehicle Speed sensor detects the Vehicle Speed and inputs a control signal to TERMINAL SP1 of the Engine Control Module.
7. Park/Neutral position SW Signal System
The Park/Neutral position SW detects whether the shift position are in neutral and parking or not, and inputs a control signal to TERMINAL NSW of the Engine Control Module (ECU).
8. A/C SW Signal System
The A/C control assembly operations to 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 turned ON, Voltage for Engine Control Module start-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 and the signal is input to TERMINAL VG of the Engine Control Module as a control signal.
11. STA 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 No.1 and No.2 and the signal is input into TERMINALS KNKL and KNKR as a control signal.

2. CONTROL SYSTEM
* SFI (Sequential Multiport Fuel Injection) System
The SFI System Monitors the Engine condition through the signals 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 SFI System produces control of 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 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 outputs to TERMINAL 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 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 Oxygen Sensor (No.1 and No.2) 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 output current to TERMINALS HTL, HTR and HTS and control the Heater.

* IAC (Idle Air Control) System
The IAC System (Rotary 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 and so on, the Engine Control Module evaluates the signals from each sensor (Input signals from (1), (4), (5), (8), (9) etc.), outputs curent to TERMINALS RSO and RSC to control Idle Air Control 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 THG to control the EGR Valve.

* ACIS (Acoustic Control Induction System)
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.
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
With the Diagnosis System, when there is a malfunction in the Engine Control Module signal System, the malfunctioning system is recorded in the memory.

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 memory or else stops the engine.