Published: 11-May-2011
2007.0 Range Rover Sport (LS), 303-04D
Fuel Charging and Controls - TDV8 3.6L Diesel (G938527)
| Item | Description |
|---|---|
| 1 | Fuel injectors (8 off, 4 per cylinder head) |
| 2 | High-pressure fuel pipe - fuel rail to injectors (8 off) |
| 3 | High-pressure fuel rail (2 off) |
| 4 | Fuel rail pressure sensor |
| 5 | RH injector leak-back pipe |
| 6 | Fuel return pipe - high-pressure fuel pump to fuel cooler |
| 7 | LH injector leak-back pipe |
| 8 | Fuel supply pipe - High-pressure fuel pump to LH fuel rail |
| 9 | High-pressure fuel pump drive gear |
| 10 | High-pressure fuel pump |
| 11 | Pressure control valve |
| 12 | Fuel supply pipe - High-pressure fuel pump to RH fuel rail |
The TDV8 engine is equipped with a high-pressure common rail fuel injection system. With this fuel injection process, a high-pressure fuel pump delivers a uniform level of pressure to the shared fuel lines (the common rails), which serve all 8 fuel injectors. Pressure is controllable, to the optimum level for smooth operation, up to 1750 bar.
The common rail system supports a pre-injection (pilot) phase, which reduces combustion noise and mechanical load.
Fuel injection pressure is generated independently of engine speed and fuel injection events.
The fuel injection timing and volume are calculated by the Engine Control Module (ECM), which then energizes the appropriate piezo actuated injector.
The common rail fuel injection system has the following features:
- High fuel injection pressures of up to 1750 bar for greater atomisation of fuel (increasing performance and lowering emissions)
- Variable injection to optimize combustion in all engine operating conditions
- Low tolerances and high precision throughout the life of the system
The fuel system is divided into 2 sub systems:
- Low-pressure system
- High-pressure system
The low-pressure system features the following components:
- In-tank fuel pump
- Fuel pressure regulator (integral to the fuel delivery module)
- Fuel filter
- Return pipes and fuel cooler
- Injector return pipes
- Fuel coolers (engine and vehicle)
The low-pressure system pressure is regulated to 0.5 bar.
The high-pressure system features the following components:
- High-pressure fuel pump
- Common fuel rails and diverter rail
- High-pressure fuel pipes
- Injectors
In-tank Fuel Pump
The electric fuel pump is located inside the fuel tank. Fuel is pumped from the tank via the in-tank fuel pump, to the high-pressure fuel pump via the fuel filter. For additional information, refer to: Fuel Tank and Lines (310-01D Fuel Tank and Lines - TDV8 3.6L Diesel, Description and Operation).
Fuel Filter
The fuel filter is located in the engine compartment on the left hand side, packaged to be protected against damage. Incorporated in the fuel filter housing is a bimetallic temperature valve, which will start to close at 30°C (86°F) and will fully close at 50°C (122°F). This allows pre-heated diesel fuel to circulate inside the fuel filter to prevent waxing in cold operating conditions.
Fuel Cooler
Two fuel coolers are fitted to the vehicle. One is located in the 'vee' of the engine block, and has a coolant system connection to aid heat transfer. The second cooler is located in the fuel return line and is a fuel to air cooler. For additional information, refer to: Fuel Tank and Lines (310-01D Fuel Tank and Lines - TDV8 3.6L Diesel, Description and Operation).
High-Pressure Fuel Pump
| Item | Description |
|---|---|
| A | Fuel return |
| B | Fuel supply - high-pressure fuel pump to RH fuel rail |
| C | Fuel supply - high-pressure fuel pump to LH fuel rail |
| D | Fuel supply |
| 1 | High-pressure fuel pump drive gear |
| 2 | Pressure control valve |
The high-pressure fuel pump is a three-piston (120 degree apart) radial plunger pump with a high-pressure displacement of 0.8 cc. As mentioned, it has the ability to produce a maximum pressure of 1750 bar.
The pump is driven from the LH inlet camshaft via a drive gear and does not need to be timed to the engine.
The required supply pressure to the pump is -0.3 bar to +0.5 bar gauge. The return pressure is -0.3 bar to +0.8 bar gauge.
The pump is sized to deliver sufficient fuel to the high-pressure rails for all engine-operating conditions.
The high-pressure fuel pump consists of the following components:
- Internal Transfer Pump (ITP)
- Volume Control Valve (VCV)
- HP pumping elements (3 of)
- Pressure Control Valve (PCV)
The ITP is a 5 vane pump. This conveys fuel to the VCV.
The VCV is a variable position solenoid valve electronically controlled by the ECM. The VCV is located between the ITP and the high-pressure pumping elements. The VCV determines the amount of fuel that is delivered to the high-pressure pumping elements. When there is no signal to the VCV the valve is closed, therefore no fuel delivery.
The 3 high-pressure pumping elements are connected together in a fuel ring circuit within the pump. There is a single high-pressure outlet connection for the high-pressure pipe to the high-pressure diverter rail.
The PCV is a variable position solenoid valve electronically controlled by the ECM. The PCV is located between the high-pressure pumping elements and the high-pressure outlet connection. The PCV regulates the amount of fuel pressure in the fuel rails and is controlled by the ECM. When there is no signal to the PCV the valve is open, therefore no rail pressure can be generated.
High-Pressure Fuel Flow
| Item | Description |
|---|---|
| A | Low-pressure fuel supply |
| B | Fuel supply to the high-pressure pumping elements |
| C | High-pressure outlet connection to the high-pressure diverter rail |
| D | Low-pressure fuel return (spill) |
| 1 | Low-pressure side of ITP |
| 2 | ITP pressure relief valve |
| 3 | Screen filter |
| 4 | VCV |
| 5 | ITP |
| 6 | Edge filter (to protect PCV) |
| 7 | PCV |
| 8 | Eccentric on high-pressure fuel pump drive shaft |
| 9 | Pumping element inlet valve |
| 10 | Pumping element outlet valve |
| 11 | High-pressure ring line |
| 12 | High-pressure fuel pump elements (3 of) |
| 13 | Lubricating valve |
The fuel induced by the ITP (5) is conveyed to the VCV (4) and the lubricating valve (13).
When the VCV is closed, the ITP pressure relief valve (2), lying parallel to the transfer pump, opens and conveys the fuel back to the low-pressure side (1) of the transfer pump.
The fuel passes through the lubricating valve (13) into the interior of the high-pressure fuel pump and from there to the fuel return (D). The fuel is used to lubricate the pump.
The VCV (4) determines the quantity of fuel (B) that is supplied to the pumping elements (12).
The fuel from the high-pressure outlets (10) of the 3 pumping elements comes together in a ring line (11) and is conveyed through the high-pressure outlet of the high-pressure fuel pump to the rails.
The PCV (7) regulates the fuel pressure in the fuel rails. Reducing rail pressure via the PCV results in fuel from the rail returning to the low-pressure fuel return (D).
| Item | Description |
|---|---|
| A | Injection pressure (bar) |
| B | Engine r/min x 100 |
| 1 | High-boost fuel pressure |
| 2 | Low-boost fuel pressure |
The high-pressure fuel pump can supply up to 1700 bar fuel pressure continuously with short excursions to 1750 bar. Pump speed is 5/6 engine speed. However it is calibrated to deliver fuel pressure dependant upon engine speed and load and is always under full control.
When the high-pressure fuel pump is rotated, pressure is created when the VCV is open and the PCV is closed. The VCV and PCV are variable position to allow variable fuel delivery and pressure control.
When the ECM actuates the piezo injectors, the rail pressure drop is off-set by additional fuel being delivered to the high-pressure rails by the PCV.
Pressure Reduction After Engine Has Stopped
The fuel pressure in the system is reduced within a few seconds after the engine has stopped as the PCV no longer has the holding current it requires, and therefore opens. No residual pressure remains in the system and the fuel is returned to the fuel return line (D) through the open PCV. The system is pressureless.
Function of a High Pressure Element
During the downward motion of the piston (3), a vacuum in the pump cylinder is generated, which opens the inlet valve (1) against the force exerted by the valve spring. The fuel (A), which is flowing past the VCV, is sucked in. At the same time the outlet valve (2) is closed due to the pressure difference between the pump cylinder and the high-pressure fuel in the ring line.
The eccentric on the high-pressure fuel pump driveshaft (5) presses the piston (3) upwards. The inlet valve (1) is then closed through the force exerted by the valve spring and the pressure being built up in the pump cylinder. The outlet valve (2) opens when the pressure in the pump cylinder is greater than the fuel pressure in the ring line (B).
Volume Control Valve (VCV)
| Item | Description |
|---|---|
| 1 | Piston |
| 2 | Sleeve |
| 3 | Compression spring |
| 4 | Coil |
| 5 | Armature |
| 6 | VCV |
The VCV is fixed directly to the high-pressure fuel pump.
The VCV regulates the fuel supply (and hence the quantity of fuel) from the transfer pump to the high-pressure fuel pump elements, depending on the fuel pressure in the rail.
This makes it possible to match the delivery of the high-pressure fuel pump to the requirements of the engine from the low-pressure side. The quantity of fuel flowing back to the main fuel supply line is kept to a minimum.
In addition, this adjustment reduces the power consumption of the high-pressure fuel pump, improving the efficiency of the engine.
-
The fuel volume control valve default is closed without electrical supply. An open circuit connector will prevent the engine from running.
-
The VCV cannot be replaced as a separate component in service.
| Item | Description |
|---|---|
| A | VCV not actuated |
| B | VCV actuated |
| 1 | Fuel supply from the transfer pump |
| 2 | Piston |
| 3 | Fuel supply to the high-pressure fuel pump |
| 4 | Coil energized |
| 5 | Quantity of fuel |
| 6 | Control current |
| 7 | VCV at constant engine speed |
VCV Not Actuated (A)
When there is no power supplied, the piston (2) closes the opening between the 2 connections (1) and (3) through the force of the compression spring. The fuel supply to the high-pressure fuel pump is interrupted.
VCV Actuated (B)
The ECM energizes the coil (4) of the valve, according to the engines requirements. The armature force is proportional to the control current and counteracts the compression spring through the moving piston (2).
As a result, the opening between the 2 connections (1) and (3) and hence the quantity of fuel (5) supplied through the connector (3) to the high-pressure fuel pump is also proportional to the control current (6). This means that the greater the opening cross-section, the greater the quantity of fuel supplied.
Pressure Control Valve (PCV)
| Item | Description |
|---|---|
| 1 | PCV |
The PCV is located on the high-pressure fuel pump. It governs the fuel pressure at the high-pressure outlet of the high-pressure fuel pump and thus, the fuel pressure within the rail. In addition, the PCV dampens any fluctuations in pressure, which occur during the delivery of fuel through the high-pressure fuel pump and through the injection process.
The PCV ensures that optimum pressure exists in the rail for every operating condition of the engine.
The PCV is an electro-magnetically operated valve with spring support.
The electrical current supplied by the ECM through the solenoid pulls back the control pin. This allows the diesel fuel to pass the ball valve and thus the fuel flow into the common rails.
The entire armature is coated with fuel for lubrication and cooling.
The PCV cannot be replaced as a separate component in service.
| Item | Description |
|---|---|
| A | PCV non-controlled |
| B | PCV controlled |
| 1 | Fuel from the high-pressure fuel pump |
| 2 | To fuel return |
| 3 | Ball valve |
| 4 | Compression spring |
| 5 | Armature |
| 6 | Coil energized |
| 7 | Control pin |
| 8 | High pressure fuel |
| 9 | Control current |
| 10 | Characteristic of the PCV |
PCV Non-controlled (A)
The ball valve (3) will only be operated through the force exerted upon it by the spring (4). Thereby, the PCV is classed as open.
PCV Controlled (B)
The current flowing through the solenoid (6) draws the pin (7) down. This in turn transfers the magnetic force via the pin to the ball valve (3). The pull of the pin, and the pressure on the ball valve, is proportional to the valve flow (9).
High-Pressure Common Fuel Rails
| Item | Description |
|---|---|
| 1 | RH high-pressure common fuel rail |
| 2 | LH high-pressure common fuel rail |
| 3 | High-pressure fuel pump |
The fuel rails are manufactured from forged steel. They store the fuel at high-pressure and prevent pressure fluctuations in the high-pressure system.
All high-pressure pipes have an internal diameter of 2.5mm except the pipes to the injectors, which are 3.0mm. Total rail volume is 33cc.
FUEL INJECTORS
| Item | Description |
|---|---|
| 1 | Harness connection |
| 2 | High-pressure connection |
| 3 | Control piston |
| 4 | Nozzle needle |
| 5 | Nozzle high-pressure chamber |
| 6 | Nozzle spray holes |
| 7 | Valve mushroom |
| 8 | Fuel return |
| 9 | Valve piston |
| 10 | Piezo actuator |
The fuel injectors are operated directly by the ECM for fuel metering (start of injection and quantity of fuel injected).
The operating components of the piezo fuel injectors are:
- The piezo actuator
- The injector body containing the hydraulic servo system
- The fuel injector nozzle
-
New injectors can be installed in any cylinder and DO NOT have to be configured.
-
Each injection event is controlled by a charge and discharge cycle allowing energy to dissipate in, and recover from, the injector. Never disconnect the wiring connector when the vehicle is running. The injector may remain open thus causing engine damage.
-
For safety reasons, the engine must be at standstill for 30 seconds before starting work on the high-pressure fuel system.
Fuel Injector Not Actuated (Not Injecting Fuel)
| Item | Description |
|---|---|
| 1 | Piezo actuator |
| 2 | High-pressure connection |
| 3 | Hydraulic force applied on control piston |
| 4 | Hydraulic force acting on tip of nozzle |
| 5 | Control piston |
| 6 | Fuel return |
| 7 | Fuel return |
| 8 | Control piston |
| 9 | Nozzle needle |
| 10 | High pressure chamber of nozzle |
| 11 | Control chamber |
| 12 | Valve mushroom |
The high-pressure fuel from the fuel-rail passes through the high-pressure connection (2) into the control chamber (11) and into the high-pressure chamber (10) of the fuel injector nozzle.
The piezo actuator (1) is currentless and the valve mushroom (12) closes the bore to the fuel return (7) by means of spring pressure.
There is however a continuous fuel return (6) to vent internal leakage within the injector.
The hydraulic force (3), which is now applied on the control piston by the fuel under high-pressure in the control chamber (11) through the control piston (8), is greater than the hydraulic force (4) acting on the tip of the nozzle (since the area of the control piston in the control chamber is greater than the area of the tip of the nozzle).
Fuel Injector Actuated (Injecting Fuel)
| Item | Description |
|---|---|
| 1 | High-pressure supply |
| 2 | Valve piston |
| 3 | Hydraulic force applied on control piston |
| 4 | Hydraulic force acting on tip of nozzle |
| 5 | Control piston |
| 6 | Fuel return |
| 7 | Piezo actuator |
| 8 | Fuel return |
| 9 | Valve piston |
| 10 | Valve mushroom |
| 11 | Control chamber |
| 12 | Control piston |
| 13 | Nozzle needle |
The piezo actuator (7) energized by the ECM extends (charging phase) and presses on the valve piston (9). The valve mushroom (10) opens the bore, which connects the control chamber (11) to the fuel return (8 then 6).
As a result, the pressure in the control chamber drops, and the hydraulic force (4) acting on the tip of the nozzle needle is now greater than the force (3) acting on the control piston in the control chamber.
The nozzle needle (13) moves upwards and the fuel passes through the 6 spray holes into the combustion chamber.
Engine Starting
During starting, the fuel rail pressure must be at least 150 bar. Should the pressure be below this figure, the injectors will not operate, resulting in the vehicle not starting.
Engine Stopped
To stop the engine the ECM stops energizing the piezo actuators, therefore, no fuel is injected and the engine speed drops to zero.