This system utilizes an engine ECU and maintains overall control of the engine, transmission and so on. An outline of the engine control is explained here.
1.Input Signals
(1)Water temp. signal circuit
The water temp. sensor detects the engine coolant temp. and has a builtin thermistor with a resistance 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 ECU.
(2)Intake air temp. signal circuit
The intake air temp. sensor is detects the intake air temp. of air cleaner, which is input as a control signal to TERMINAL THA of the engine ECU.
The intake air temp. sensor is detects the intake air temp. of inter cooler, which is input as a control signal to TERMINAL THIA of the engine ECU.
(3)RPM signal circuit
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 G+ of the engine ECU, and engine RPM is input into TERMINAL NE+.
(4)Throttle signal circuit
The accelerator position sensor detects the accelerator pedal opening angle, which is input as a control signal to TERMINALS VPA and VPA2 of the engine ECU.
(5)Vehicle speed signal circuit
The speed sensor detects the vehicle speed and inputs a control signal to TERMINAL SPD of the engine ECU via the combination meter.
(6)Battery signal circuit
Voltage is constantly applied to TERMINAL BATT of the engine ECU. When the ignition SW is turned to on, voltage for engine ECU operation is applied via the MAIN relay to TERMINAL +B of the engine ECU.
(7)Started signal circuit
To confirm that the engine is cranking, the voltage applied to the starter motor during cranking is detected and is input as a control signal to TERMINAL STA of the engine ECU.
(8)Fuel temp. signal circuit
The fuel temp. sensor is detects the fuel temp., which is input as a control signal to TERMINAL THF of the engine ECU.
(9)Intake air vacuum pressure signal system
Intake air vacuum pressure is detected by the turbo pressure sensor and is input as a control signal to TERMINAL PIM of the engine ECU.
2.Control System
*EGR control
The EGR control system detects the signals from each sensor, then the current is output to the TERMINAL EGR to control the VRV (EGR).
*Common rail pressure control
The target rail pressure is calculated according to the engine status (Accelerator opening, engine speed) and environmental change detected by sensors. The fuel amount to be pressurefed from the supply pump is calculated so as to match the indicated value of rail pressure sensor with the target value and the signal is sent to the intake amount adjusting valve of the supply pump in order to control the rail pressure.
*Fuel injection timing control
The fuel injection timing is controlled by calculating the basic fuel injection timing based on the engine status (Accelerator opening, engine speed), making corrections according to environmental change detected by sensors, then sending a signal to the solenoid control valve of the injector via the injector driver (EDU).
*Fuel injection volume control
The fuel injection volume is controlled by calculating the basic fuel injection volume based on the engine status (Accelerator opening, engine speed), making corrections according to environmental change detected by sensors and the inside pressure conditions in the rail, then sending a signal to the solenoid control valve of the injector via the injector driver (EDU).
*Pilot injection control
The fuel injection volume and timing are controlled by calculating the pilot injection volume/timing based on the engine status (Accelerator opening, engine speed), making corrections according to environmental change detected by sensors, then sending a signal to the solenoid control valve of the injector via the injector driver (EDU).
3.Diagnosis System
With the diagnosis system, when there is a malfunctioning in the engine ECU signal system, the malfunction system is recorded in the memory. The malfunctioning system can be found by reading the display (Code) of the check engine warning light.
4.FailSafe 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 failsafe system either controls the system by using data (Standard values) recorded in the engine ECU memory or else stops the engine.