Contents: Component arrangement ⇩ General information ⇩ Low pressure circuit ⇩ High pressure circuit ⇩ Pressure regulator (PCV) ⇩ Nozzles ⇩
Component arrangement
| Item name | Spare part catalog number | Description |
| 1 | - | High pressure fuel rail (HP) (2 pcs.) |
| 2 | - | High pressure pipe (HP) between the fuel rail and the injector (6 pcs.) |
| 3 | - | Nozzles (6 pcs.) |
| 4 | - | Low Pressure (LP) Fuel Line: Backflow |
| 5 | - | High pressure pipe between the high pressure fuel pump and the fuel rail |
| 6 | - | Low pressure fuel pipe: drain from injectors |
| 7 | - | Injector nipple (6 pcs.) |
| 8 | - | High pressure fuel pump |
| 9 | - | High pressure fuel pump pulley |
| 10 | - | High pressure distribution ramp |
| 11 | - | Crankshaft Rear Accessory Drive Belt Tensioner (READ) |
| 12 | - | Left exhaust camshaft pulley |
General information
The TdV6 engine uses a common rail fuel injection system. In this system, the high-pressure fuel pump (HPFP) supplies fuel under one pressure to two rails, from which the fuel is supplied to all six injectors. The pressure is maintained at an optimal level for smooth operation and can reach 1650 bar.
The accumulator system provides two-phase injection (preliminary and main phases), which reduces combustion noise and mechanical stress on engine parts.
Injection pressure is created regardless of the engine crankshaft speed and fuel injection timing.
The Engine Control Module (ECM) calculates the fuel injection timing and volume and supplies power to the appropriate piezoelectrically actuated injector.
The accumulator injection system has the following characteristics:
- To achieve finely dispersed fuel fragmentation, injection pressure can reach up to 1650 bar. (fine atomization improves performance and reduces toxic combustion emissions)
- Independent regulation of injection parameters by cylinders ensures optimal combustion in all modes
- High precision operation throughout the entire service life of the system
- Low pressure circuit (LP)
- High pressure circuit (HP)
- Fuel pump located in the fuel tank
- Fuel pressure regulator, integrated fuel delivery module
- Fuel filter
- Return lines and fuel cooler
- Backflow tubes from injectors
- Fuel coolers (engine and car)
The high pressure circuit includes the following components:
- High pressure fuel pump
- Fuel rails and distribution rail
- High pressure fuel pipes
- Nozzles
Low pressure circuit
Fuel pump located in the fuel tank
The electric fuel pump is mounted in the fuel tank. The fuel pump delivers fuel from the tank to the injection pump through the fuel filter. For more information, refer to Fuel Tank and Lines (310-01C Fuel Tank and Lines - 2.7L Diesel)
Fuel filter
The fuel filter is located on the left side of the engine compartment and is protected from mechanical damage. The fuel filter housing contains a bimetallic bypass valve that begins to close at 30°C and closes completely at 50°C. This ensures the circulation of heated diesel fuel inside the fuel filter and prevents paraffin formation in cold weather.
Fuel cooler
The fuel system is equipped with two fuel coolers. One is located in the cylinder block V and provides heat removal by connecting to the cooling system. The second cooler is integrated into the return line and is cooled by air. For more information, refer to Fuel Tank and Lines (310-01C Fuel Tank and Lines - 2.7L Diesel)
High pressure circuit
High pressure fuel pump
High pressure fuel pump, radial type, three-plunger (plungers are located at 120 degrees of the circle) with a working volume of 0.8 cc. As noted earlier, the pump can create pressure up to 1650 bar. The pump body is cast iron, and the flange is aluminum.
The pump is driven by a toothed belt from the camshaft. After replacing the belt during maintenance, there is no need to synchronize the pump with the crankshaft rotation angle.
The feed pressure to the pump must be between -0.3 and +0.5 bar. The pressure in the return circuit must be between -0.3 and +0.8 bar.
The pump has a capacity sufficient to supply fuel rails with fuel in any engine operating mode. The high-pressure pump contains the following units:
- Internal Transfer Pump (ITP)
- Pump capacity controller (VCV)
- Plungers (3 pcs.)
- Pressure regulator (PCV)
The capacity regulator is a solenoid spool valve that is controlled by the ECM. The VCV is located between the ITP and the plunger pairs. The VCV regulates the amount of fuel supplied to the plunger pairs. If there is no signal to the VCV, the regulator valve closes and the fuel supply is stopped.
Three plunger pairs are connected by a ring fuel channel inside the pump body. The high-pressure fuel pump has one outlet fitting, to which a high-pressure pipe is connected, connecting the high-pressure fuel pump to the distribution ramp.
The pressure regulator (PCV) is an electromagnetic spool valve that is controlled by the ECM. The PCV is located between the plunger pairs and the outlet fitting of the injection pump. The pressure regulator controls the fuel pressure in the fuel rails and is controlled by the ECM. If there is no signal to the PCV, the regulator valve is open and no pressure is created in the fuel rails.
Fuel movement in the high pressure circuit
| Item name | Spare part catalog number | Description |
| A | - | Fuel supply from the low pressure circuit |
| B | - | Fuel supply to plunger pairs |
| C | - | High pressure pipe to the distribution rail |
| D | - | Backflow main (injector drainage) |
| 1 | - | Booster pump inlet |
| 2 | - | Pressure reducing valve of the booster pump |
| 3 | - | Mesh filter |
| 4 | - | Capacity Control (VCV) |
| 5 | - | Booster pump (ITP) |
| 6 | - | Slotted filter (to protect the pressure regulator valve) |
| 7 | - | Pressure regulator (PCV) |
| 8 | - | - |
| 9 | - | Eccentric shaft of the fuel injection pump drive |
| 10 | - | Plunger pair inlet valve |
| 11 | - | Plunger pair outlet valve |
| 12 | - | High pressure annular channel |
| 13 | - | Plunger pairs (3 pcs.) |
| 14 | - | Lubricating valve |
Fuel from the booster pump (5) is supplied to the capacity regulator (4) and to the lubricating valve (14). When the capacity regulator valve is closed, the pressure reducing valve of the booster pump (2), connected in parallel with this pump, opens and directs the fuel back to the inlet of the booster pump (1).
The fuel passes through the lubricating valve (14) into the high-pressure pump and from there into the return circuit (D). This fuel is used to lubricate the pump.
The performance regulator (4) determines the amount of fuel (B) supplied to the plunger pairs (13).
Fuel from the high-pressure outlet pipes (11) of the three plunger pairs is collected together in a ring line (12) and transferred through the high-pressure outlet pipe to the ramps.
The fuel pressure in the rails is controlled by the pressure regulator (7). When the regulator reduces the pressure, the fuel returns to the low-pressure circuit (D).
| Item name | Spare part catalog number | Description |
| A | - | Pump pressure (bar) |
| B | - | Pump shaft speed (rpm) |
The high-pressure fuel pump can create fuel pressure up to 1600 bar in continuous mode and up to 1650 bar for a short time. The pump shaft speed is 5/6 of the engine crankshaft speed. However, the pump is configured in such a way that the fuel pressure depends on the engine crankshaft speed and load and is continuously adjusted.
Fuel pressure is created by the rotation of the pump shaft when the VCV valve is open and the PCV valve is closed. The VCV and PCV valves can be in different positions, which affects the pump performance and fuel pressure.
When the engine control unit actuates the piezoelectric actuator of the injectors, the pressure drop in the rail is compensated by the pressure regulator.
Pressure drop after engine stop
After the engine is stopped, the system pressure drops within a few seconds because the pressure regulator is de-energized and its valve opens. There is no residual pressure left in the system and fuel is released into the return line (D) through the open PCV valve. There is no pressure left in the system.
Purpose of high pressure element A
Filling with fuel
When the plunger (3) moves downwards, a vacuum is created above it, which, overcoming the resistance of the spring, opens the inlet valve (1). Fuel (A), passing through the control valve, is sucked into the plunger cylinder. The outlet valve (2) is closed at this time due to the pressure difference in the plunger cylinder and the high-pressure annular channel.
Fuel supply
The eccentric (5) of the high-pressure pump drive shaft moves the plunger (3) upward. The inlet valve (1) closes under the action of the spring, and the pressure in the pump cylinder begins to increase. The outlet valve (2) opens when the pressure in the pump cylinder becomes higher than the pressure in the annular channel (B) of the pump.
Pump capacity controller (VCV)
| Item name | Spare part catalog number | Description |
| 1 | - | Piston |
| 2 | - | Sleeve |
| 3 | - | Compression spring |
| 4 | - | Winding |
| 5 | - | Core |
| 6 | - | Capacity Control (VCV) |
The performance regulator is installed directly on the fuel injection pump.
The VCV valve regulates the amount of fuel supplied from the booster pump to the plunger pairs depending on the pressure in the fuel rail.
In this way, it is possible to match the required performance of the high-pressure fuel pump with the fuel supply to its input. At the same time, the amount of fuel going to the backflow is reduced to a minimum.
In addition, this reduces the load on the fuel injection pump drive and, consequently, the specific fuel consumption.
NOTE: When power is removed, the capacity control valve defaults to the closed position. Removing power to the control valve will prevent the engine from operating.
NOTE: The capacity regulator is not replaceable as a separate unit.
| Item name | Spare part catalog number | Description |
| A | - | Performance regulator is off |
| B | - | Performance regulator is enabled |
| 1 | - | Fuel supply from the booster pump |
| 2 | - | Piston |
| 3 | - | Fuel supply to the injection pump |
| 4 | - | Winding power is on |
| 5 | - | Amount of fuel |
| 6 | - | Control current strength |
| 7 | - | Constant speed crankshaft regulator |
Performance regulator off (A)
In the absence of power supply, piston (2), under the action of the compression spring, closes the opening between channels (1) and (3). The fuel supply to the high-pressure fuel pump is blocked.
Performance regulator on (B)
The engine control unit supplies power to the valve coil (4) in accordance with engine requirements. The coil's retracting force, proportional to the control current, overcomes the spring force and moves the piston (2).
As a result, the piston opens two holes (1) and (3). The amount of fuel (5) supplied through the nozzle (3) to the high-pressure fuel pump is proportional to the current (6). This means that the larger the flow area, the greater the pump performance.
Pressure regulator (PCV)
The pressure regulator is installed on the high-pressure fuel pump. It is designed to regulate the pressure at the outlet of the high-pressure fuel pump and, consequently, in the fuel rail. In addition, the pressure regulator dampens pressure fluctuations that occur due to the operation of the high-pressure fuel pump and injectors.
The pressure regulator ensures optimal pressure in the rails in all engine operating modes.
The pressure regulator is a solenoid valve with a spring-loaded spool.
When the ECU supplies power to the valve coil, the valve stem is pulled into the coil, causing diesel fuel to pass the check ball and enter the fuel rails.
For cooling and lubrication, the core is immersed in fuel.
NOTE: The pressure regulator is not replaceable as a separate unit.
| Item name | Spare part catalog number | Description |
| A | - | The pressure regulator is not controlled |
| B | - | The pressure regulator is controlled |
| 1 | - | Fuel from the injection pump |
| 2 | - | To the fuel return line |
| 3 | - | Ball valve |
| 4 | - | Compression spring |
| 5 | - | Core |
| 6 | - | Winding power is on |
| 7 | - | Stock |
| 8 | - | High pressure fuel |
| 9 | - | Control current strength |
| 10 | - | Pressure regulator characteristics |
The publication was copied from a web resource [LRman.ru]
Pressure regulator not controlled (A)
The ball valve (3) is only under the action of the spring force (4). In this case, the pressure regulator is considered open.
The pressure regulator is controlled by (B)
The current flowing through the winding (6) moves the rod (7) downwards. In this case, the magnetic force is transmitted through the rod to the ball valve (3). The balance of pressure on the ball from the rod side and from the fuel side determines the fuel flow through the valve (9).
High pressure fuel rails
High-pressure fuel rails are made of forged steel. Fuel rails act as hydraulic fuel accumulators and, in addition, dampen pressure surges in the high-pressure circuit.
The high-pressure pipes have an internal diameter of 2.5 mm, except for the pipes to the injectors, which have a diameter of 3.0 mm. The total volume of the fuel rails is 33 cc.
Nozzles
| Item name | Spare part catalog number | Description |
| 1 | - | Electrical connector |
| 2 | - | High pressure fuel supply |
| 3 | - | Control piston |
| 4 | - | Spray needle |
| 5 | - | High pressure chamber of the atomizer |
| 6 | - | Spray holes |
| 7 | - | Mushroom valve |
| 8 | - | Fuel drain |
| 9 | - | Valve piston |
| 10 | - | Piezoelectric actuator |
Fuel metering and the start of fuel delivery are controlled directly by the ECM.
The piezoelectric fuel injector consists of three main parts:
- Piezo actuator
- Injector body with hydraulic servo booster system
- Fuel injector nozzle
NOTE: New injectors DO NOT require calibration and can be installed in any cylinder.
NOTE: Each injection is controlled by a charge cycle in which the electrical charge supplied to the injector is increased, and a discharge cycle in which the remaining electrical charge is dissipated. Never disconnect the electrical connector from the injector while the engine is running. The injector may remain open, causing engine damage.
NOTE: For safety reasons, the engine should be turned off for 30 seconds before working on the high pressure fuel system.
Fuel injector is off (fuel is not injected)
| Item name | Spare part catalog number | Description |
| 1 | - | Piezoelectric actuator |
| 2 | - | High pressure fuel supply |
| 3 | - | Pressure acting on the control piston |
| 4 | - | Pressure acting on the spray needle |
| 5 | - | Control piston |
| 6 | - | Fuel drain |
| 7 | - | Fuel drain |
| 8 | - | Control piston |
| 9 | - | Spray needle |
| 10 | - | High pressure chamber of the injector |
| 11 | - | Control chamber |
| 12 | - | Mushroom valve |
Fuel under high pressure passes from the rail through the fitting (2) into the control chamber (11) and into the high-pressure chamber (10) of the injector nozzle.
Current is not supplied to the piezo actuator (1), and the mushroom valve (12), under the action of the spring, closes the opening of the return drain channel (7).
Fuel resulting from internal leaks in the injector is discharged through the return channel (6).
The hydraulic pressure (3) applied to the control piston (8) from the fuel side in the control chamber (11) is greater than the force of the hydraulic pressure (4) applied to the injector needle (the area of the control piston is greater than the area of the injector needle).
Fuel injector on (fuel injection)
| Item name | Spare part catalog number | Description |
| 1 | - | High pressure fuel supply |
| 2 | - | Valve piston |
| 3 | - | Pressure acting on the control piston |
| 4 | - | Pressure acting on the spray needle |
| 5 | - | Control piston |
| 6 | - | Fuel drain |
| 7 | - | Piezoelectric actuator |
| 8 | - | Fuel drain |
| 9 | - | Valve piston |
| 10 | - | Mushroom valve |
| 11 | - | Control chamber |
| 12 | - | Control piston |
| 13 | - | Spray needle |
The piezoelectric element (7) expands under the influence of the electric charge from the ECM. (charge cycle) and presses on the piston (9) of the valve. The mushroom valve (10) opens the hole that connects the control chamber (11) with the backflow channels (8 and 6).
As a result, the pressure in the control chamber drops, and the hydraulic force (4) acting on the spray needle becomes greater than the force (3) acting on the piston in the control chamber.
The nozzle needle (13) moves upward and fuel is injected through six nozzle holes into the combustion chamber.
Starting the engine
To start the engine, the pressure in the fuel rails must be at least 150 bar. If the pressure is lower than the specified value, the injectors will not work and, therefore, the engine will not start.
Engine stop
To stop the engine, the ECM cuts off power to the piezo elements. No fuel is injected into the cylinders, and the engine speed drops to zero.
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