ECD SYSTEM SYSTEM DESCRIPTION

1. Common rail system:

   The common rail system uses high-pressure 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 is pressurized and supplied with fuel 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 injector driver, provides an electric current to the solenoid valve in each injector assembly 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 solenoid valve inside each injector assembly 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.

   

2. Common rail system components:

   Component	Description
   Common rail assembly	Stores high-pressure fuel supplied by fuel supply pump assembly
   Fuel supply pump assembly	Operated by crankshaft. Supplies high-pressure fuel to common rail assembly.
   Injector assembly	Injects fuel into combustion chamber based on signals from ECM
   Fuel pressure sensor	Monitors internal fuel pressure of common rail assembly and sends signals to ECM
   Pressure discharge valve	Opens based on signals from ECM when sudden deceleration occurs, or when ignition switch is off to prevent fuel pressure from becoming too high
   Suction control valve	Adjusts fuel volume supplied to common rail and regulates internal fuel pressure based on signals from ECM
   Check valve	Maintains pressure of fuel that discharges from injector

3. Diagnostic Trouble Codes (DTC) table for the common rail system:

   Tech Tips

   This table indicates typical DTC combinations for each malfunction.

   Trouble Area	Malfunction	DTC No.
   Injector assembly	Open or short in injector circuit	P0200, P0093*
   	Stuck open	P0093
   	Stuck closed	-
   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	P1271, P1272, P0088*, P0093*, P1229*
   	Stuck open	P0093
   	Stuck closed	P1272, P0088*
   Suction control valve	Open or short in suction control valve circuit	P0627, P1229, P0088*
   	Stuck open	P1229, P0088*
   	Stuck closed	-
   Injector driver	Faulty injector driver	P0093*, P0200*, P1271*, P1272*
   Common rail system (Fuel system)	Fuel leaks in high-pressure area	P0093

   *: There may be no DTCs stored depending on the condition of the malfunction.

4. 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 (200 MPa [2,039 kgf/cm2, 29,007 psi] or higher)
   P0093	Fuel leaks in high-pressure areas
   P0190	Open or short in fuel pressure sensor circuit (output voltage is too low or too high)
   P0191	Fuel pressure sensor out of range (Low output)
   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)
   P0200	Open or short in injector driver or injector circuit
   P0627	Open or short in suction control valve circuit
   P1229	Fuel overfeed
   P1271	Open or short in pressure discharge valve circuit
   P1272	Closed malfunction of the pressure discharge valve

The ECM controls the fuel injection system through the injector driver, injector assemblies and fuel supply pump assembly.

The ECM determines the injection volume and injection timing based on signals from the accelerator position sensor, crankshaft position sensor and camshaft position sensor. The injector driver controls the injector assemblies based on signals from the ECM. The injector driver also controls the suction control valve installed on the supply pump to help regulate fuel pressure.

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

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.

1. When the suction control valve opening is small:

   
   

   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).

      

2. When the suction control valve opening is large:

   
   

   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).