ECD SYSTEM > SYSTEM DESCRIPTION

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1. The common rail system uses high-pressure fuel for improved fuel economy and to provide robust engine power, while suppressing engine vibration and noise.
   This system stores fuel, which has been pressurized and supplied by the supply pump, in the common rail. 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 regulates the fuel injection timing and volume by using the EDU to provide an electric current to the solenoid valve in the injector. 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 has a 2-Way Valve (TWV) inside the injector to open and close the fuel passage. As a result, both fuel injection time and fuel injection volume can be precisely regulated by the ECM.
   The common rail system provides two split fuel injections. In order to soften combustion shock, this system performs "pilot-injection" as the subsidiary fuel 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 limiter	Opens pressure limiter valve to reduce internal pressure in common rail when common rail pressure exceeds specified level
   Suction control valve	Based on signals from ECM, adjusts fuel volume supplied to common rail and regulates internal fuel pressure

1. HINT:

   This table indicates typical DTC combinations for each malfunction occurrence.

   
   
   
   
   
   
   

   Trouble Area	Malfunction	Refer to
   Injector	Open or short in injector circuit	A
   Injector	Stuck open	B
   Injector	Stuck closed	C
   Fuel pressure sensor	Open or short in fuel pressure sensor circuit or pressure sensor output fixed	D
   Pressure limiter	Stuck open	E
   Pressure limiter	Stuck closed	F
   Suction control valve	Open or short in suction control valve circuit	G
   Suction control valve	Stuck open	H
   Suction control valve	Stuck closed	I
   EDU	Faulty EDU	J
   Common rail system (Fuel system)	Fuel leaks in high-pressure areas	K

HINT:

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

1. Small opening of the suction control valve:
   
   

   1. When the opening of the suction control valve is small, the fuel suction path is kept narrow. Therefore the transferable fuel volume is reduced.
      

   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. Pumping will start when the fuel pressure becomes higher than the common rail pressure.
      

      
      
      
      





2. Large opening of the suction control valve:
   
   

   1. When the opening of the suction control valve is large, the fuel suction path is kept wide. Therefore the transferable fuel volume is increased.
      

   2. If the plunger stroke is full, the suction volume becomes large because of the wide path.
      

   
   
   

   3. Pumping will start when the fuel pressure becomes higher than the common rail pressure.