ECD SYSTEM(for CCo) SYSTEM DESCRIPTION

ENGINE CONTROL SYSTEM

*1	ECM	*2	Fuel Supply Pump
*3	Suction Control Valve	*4	Fuel Temperature Sensor
*5	Common Rail	*6	Fuel Pressure Sensor
*7	Pressure Discharge Valve	*8	Injector Driver (EDU)
*9	EDU Relay	*10	Injector
*11	Diesel Throttle Body Assembly	*12	Manifold Absolute Pressure Sensor
*13	EGR Valve Assembly	*14	GLOW Relay
*15	Glow Plug	*16	Engine Coolant Temperature Sensor
*17	Intake Air Temperature Sensor (Turbo)	*18	Intercooler
*19	Camshaft Position Sensor	*20	Crankshaft Position Sensor
*21	Mass Air Flow Meter Assembly	*22	Intake Air Temperature Sensor (built into Mass Air Flow Meter Assembly)
*23	Turbocharger	*24	Vacuum Regulating Valve Assembly (for Turbocharger Control)
*25	Vacuum Switching Valve Assembly (for EGR Cooler)	*26	EGR Cooler
*27	Accelerator Pedal Position Sensor	*28	Generator
*29	Cooling Fan Relay	*30	Battery

COMMON RAIL SYSTEM DESCRIPTION

Common rail system:
The common rail system uses high-pressurized fuel for improved fuel economy. This system also provides robust engine power, while suppressing engine vibration and noise.
This system stores fuel in the common rail, which has been pressurized and supplied by the supply pump. By storing fuel at high-pressure, the common rail system can provide fuel at stable fuel injection pressures, regardless of engine speed or engine load.
The ECM, using the EDU, provides an electric current to the piezo actuator in each injector to regulate the fuel injection timing and volume. The ECM also monitors the internal fuel pressure of the common rail using the fuel pressure sensor. The ECM causes the supply pump to supply the fuel necessary to obtain the target fuel pressure.
In addition, this system uses a piezo actuator inside each injector to open and close the fuel passages. Therefore, both fuel injection time and fuel injection volume can be precisely regulated by the ECM.
The common rail system allows a two stage fuel injection process. In order to soften combustion shock, this system performs "pilot-injection" prior to the main fuel injection. This helps to reduce engine vibration and noise.

Common rail system components:


Component	Description
Common rail	Stores high-pressure fuel produced by supply pump
Supply pump	Operated by crankshaft Supplies high-pressure fuel to common rail
Injector	Injects fuel to combustion chamber based on signals from ECM
Fuel pressure sensor	Monitors internal fuel pressure of common rail and sends signals to ECM
Pressure Discharge Valve	Based on signals from the ECM, opens valve when sudden deceleration is occurred, or when the ignition switch is OFF to prevent the fuel pressure from becoming too high.
Suction control valve	Based on signals from ECM, adjusts fuel volume supplied to common rail and regulates internal fuel pressure
Check valve	Keeps pressure that discharges from injector

Diagnostic trouble codes (DTCs) table for the common rail system

Tip:

This table indicates typical DTC combinations for each malfunction occurrence.


Trouble Area	Malfunction	DTC No.
Injector	Open or short in injector circuit	P0093*, P0201, P0202, P0203, P0204, P062D
	Stuck open	P0093
	Stuck closed	P0301, P0302, P0303, P0304
Fuel pressure sensor	Open or short in fuel pressure sensor circuit or pressure sensor output fixed	P0087, P0190, P0191, P0192, P0193
Pressure discharge valve	Open or short in pressure discharge valve circuit	P0088, P0093, P1229*, P1271, P1272
	Stuck open	P0093
	Stuck closed	P0088*, P1272
Suction control valve	Open or short in suction control valve circuit	P0088*, P0627, P1229
Suction control valve	Stuck open	P0088*, P1229
EDU	Faulty EDU	P0093, P0201, P0202, P0203, P0204, P062D, P1271, P1272
Common rail system (Fuel system)	Fuel leaks in high-pressure area	P0093

*: There may be no DTC output depending on the condition of the malfunction.

Diagnostic trouble code description for the common rail system:


DTC No.	Description
P0087	Fuel pressure sensor output does not change
P0088	Internal fuel pressure too high (220000 kPa [2243.4 kgf/cm², 31900 psi] or more)
P0093	Fuel leaks in high-pressure areas
P0190	Open or short in fuel pressure sensor circuit (output voltage is too low or too high)
P0192	Open or short in fuel pressure sensor circuit (output voltage is too low)
P0193	Open or short in fuel pressure sensor circuit (output voltage is too high)
P0201	Open or short in No. 1 injector circuit
P0202	Open or short in No. 2 injector circuit
P0203	Open or short in No. 3 injector circuit
P0204	Open or short in No. 4 injector circuit
P0301	Cylinder 1 misfire detected
P0302	Cylinder 2 misfire detected
P0303	Cylinder 3 misfire detected
P0304	Cylinder 4 misfire detected
P0627	Open or short in suction control valve circuit
P062D	Open or short in injector driver or injector circuit
P1229	Fuel over-feed
P1271	Open or short in pressure discharge valve circuit
P1272	Pressure discharge valve stuck close

INJECTION CONTROL SYSTEM DESCRIPTION

The ECM controls the fuel injection system through the EDU, injectors, and supply pump.

The ECM determines the injection volume and injection timing based on signals from the acceleration position sensor, crank position sensor, and camshaft position sensor. Based on the signals from the ECM, the EDU controls the injectors. The EDU also controls the suction control valve installed on the supply pump to help regulate fuel pressure.

The Piezo type injector used in the 2AD-FTV engine makes noise when the engine is idling because this injector operates at high speed. Therefore, the EDU controls the injector to operate at low speed when the engine is idling based on signals from the ECM to achieve noise reduction.

The feed pump is used to pump fuel from the fuel tank to the supply pump.

SUPPLY PUMP OPERATION SYSTEM DESCRIPTION

The rotation of the eccentric cam in the supply pump causes the ring cam in the supply pump to push plunger A upward as illustrated below. The spring force pulls plunger B (located opposite to plunger A) upward. As a result, plunger B draws the fuel in, and plunger A pumps fuel out at the same time.

SUCTION CONTROL VALVE OPERATION SYSTEM DESCRIPTION

Tip:

The ECM controls the suction control valve operation to regulate the fuel volume that is produced by the supply pump for the common rail. This control is performed to regulate the internal fuel pressure of the common rail to the targeted injection pressure.

Small opening of the suction control valve:
1. When the opening of the suction control valve is small, the volume of supplied fuel is small.
2. The suction volume becomes small due to the narrow path despite the plunger stroke being full. The difference between the geometrical volume and suction volume creates a vacuum.
3. Pump output will start when the fuel pressure at (A) becomes higher than the common rail pressure (B).
Large opening of the suction control valve:
1. When the opening of the suction control valve is large, the volume of supplied fuel is increased.
2. If the plunger stroke is full, the suction volume becomes large because of the wide path.
3. Pump output will start when the fuel pressure at (A) becomes higher than the common rail pressure (B).