Land Rover Discovery: Fuel Charging and Controls - Ingenium i4 2.0l Diesel / Description and Operation

COMPONENT LOCATION

1. Fuel injector (4 off)
2. Low Pressure (LP) pipe - injector leak-off
3. High Pressure (HP) pipe - fuel rail to injector (4 off)
4. Low Pressure (LP) pipe - fuel rail leak-off
5. Fuel Pressure Control Valve (PCV)
6. Low Pressure (LP) pipe - HP pump leak-off
7. High Pressure (HP) - HP pump to fuel rail
8. Fuel supply pipe - filter to lift pump
9. High Pressure (HP) fuel pump and integral lift pump
10. High Pressure (HP) common fuel rail
11. Fuel Rail Pressure (FRP) sensor

OVERVIEW

The Ingenium I4 2.0L Diesel engine fuel charging and control system provides precise and instantaneous fuel delivery to the engine combustion chambers. The fuel system features a Bosch common rail system which is monitored and controlled by the Powertrain Control Module (PCM), to precisely control the fueling strategy.

DESCRIPTION

HIGH PRESSURE FUEL PUMP

1. Low Pressure (LP) fuel supply connection - fuel filter to fuel pump
2. LP fuel return connection - fuel pump to tank
3. High Pressure (HP) fuel supply connection - fuel pump to fuel rail

1. Pump plunger
2. Fuel metering valve
3. HP fuel pump driveshaft
4. Fuel temperature sensor

The High Pressure (HP) fuel pump located on the left side of the cylinder block and secured with three bolts. The pump is driven by the camshaft timing chain via a sprocket attached the HP fuel pump driveshaft.

The HP pump is a single plunger, cam-driven type with two pumping strokes per revolution. The HP fuel pump is capable of producing a maximum fuel pressure of 1800 bar (26,107 psi).

The HP fuel pump consists of the following components:

• Single plunger HP pump
• Fuel temperature sensor
• Fuel metering valve.

A controlled amount of fuel is allowed to leak off through the HP fuel pump, and returned through a leak-off pipe to the fuel tank. The leak-off fuel provides the cooling and lubrication for the HP fuel pump's internal components.

FUEL METERING VALVE

The fuel metering valve is mounted on the High Pressure (HP) fuel pump.

The fuel metering valve is a variable position solenoid-operated valve that is controlled by the Powertrain Control Module (PCM) with a Pulse Width Modulation (PWM) signal. The fuel metering valve controls the quantity of fuel delivered to the plunger.

When the HP fuel pump rotates, pressure is created when the fuel metering valve is open and the fuel rail mounted fuel Pressure Control Valve (PCV) is closed. The fuel metering valve and the fuel PCV are variable position valves, and used by the PCM to control fuel delivery and fuel system pressure.

The fuel metering valve is normally open when the solenoid is not energized by the PCM.

For additional information, refer to: Electronic Engine Controls (303-14A Electronic Engine Controls - TD4 2.2L Diesel, Description and Operation).

FUEL RAIL

1. High Pressure (HP) pipe connection - fuel rail to fuel injector (4 off)
2. HP fuel supply connection - HP fuel pump to fuel rail
3. Low Pressure (LP) fuel return connection - fuel rail to fuel filter (via a cooler)

1. Fuel Rail Pressure (FRP) sensor
2. Fuel rail
3. Fuel Pressure Control Valve (PCV)

The fuel rail is secured to the cylinder head with two bolts. The fuel rail stores pressurized fuel from the High Pressure (HP) fuel pump, and prevents pressure fluctuations in the HP system. A Fuel Rail Pressure (FRP) sensor and a fuel Pressure Control Valve (PCV) are installed into the threaded bore at each end of the fuel rail.

HP fuel pipes connect the fuel rail to the HP fuel pump and fuel injectors. A leak-off pipe connects the fuel rail to the fuel filter via a cooler.

The FRP sensor and fuel PCV are an integral assembly and must not be separated. If a fault occurs that requires component renewal, then the complete fuel rail assembly must be renewed.

FUEL PRESSURE CONTROL VALVE

The fuel Pressure Control Valve (PCV) is mounted in a threaded bore on the rear of the fuel rail and is connected to the Powertrain Control Module (PCM) via the engine harness. The fuel PCV is a solenoid-operated valve controlled by a Pulse Width Modulation (PWM) signal. The PCM operates the fuel PCV to adjust the fuel pressure within the fuel rail. Relieved fuel is directed through the fuel rail leak-off pipe to the fuel filter return circuit. The returned fuel is used to warm the filter.

The fuel PCV is normally open when the solenoid is not energized by the PCM.

The fuel PCV is also used by the PCM to provide direct control of the fuel system, in the following situations:

• During sudden transient phases in engine speed (suddenly lifting off the accelerator pedal, for example) where the fuel metering valve action is not sufficient to affect the supply of fuel to the fuel rail.
• To control fuel pressure if the fuel metering valve fails.
• During the fuel heating period, when supply fuel temperature is less than 40ºC (104ºF), the fuel metering valve is fully opened by the PCM and the High Pressure (HP) fuel pump compresses a maximum quantity of fuel to raise the fuel temperature. The fuel PCV is then modulated by the PCM to provide leak-off fuel from the fuel rail to the fuel filter return circuit. The fuel is then recirculated through the fuel filter and back to the HP fuel pump.
• During engine shutdown to progressively collapse the fuel rail pressure.

FUEL RAIL PRESSURE SENSOR

The Fuel Rail Pressure (FRP) sensor is mounted in a threaded bore in the front of the fuel rail and connected to the Powertrain Control Module (PCM) via the engine harness. The pressure sensor is provided with a 5V power supply, ground and signal connections. The FRP is a piezo-resistive type sensor containing an actuating diaphragm. Deflection of the diaphragm provides a proportional signal output voltage to the PCM, dependant on the fuel pressure within the fuel rail.

Pressure Sensor Parameters

The Powertrain Control Module (PCM) compares the sensor signal voltage to stored memory values, to calculate the actual fuel pressure present in the fuel rail. The PCM then uses the fuel rail pressure information to control the operating position of the fuel metering valve and the fuel Pressure Control Valve (PCV).

For additional information, refer to: Electronic Engine Controls (303-14A Electronic Engine Controls - TD4 2.2L Diesel, Description and Operation).

FUEL INJECTORS

1. Electrical connection to the Engine Control Module (ECM)
2. High Pressure (HP) fuel supply connection from the fuel rail
3. Data matrix and injector information
4. Low Pressure (LP) fuel leak-off connection to the fuel filter

There are two types of injectors available; one for the Ingenium I4 2.0L diesel 180PS output and one for the 163PS output. These are differentiated by the nozzle flows, see below table.

The four fuel injectors are of the solenoid-actuated type, each manufactured with eight spray holes in the injector nozzle. The injectors are located centrally within the cylinder head combustion chambers to spray atomized fuel directly onto the toroidal dome of the pistons.

During manufacture, each injector is tested to measure the actual injected quantity of fuel, compared to a reference quantity for simulated conditions.

The tests are used to categorize the injectors, the difference in the injection analysis results is translated to a 7-digit alpha-numerical code that is etched on the injector casing.

The 7-digit codes are stored in the Powertrain Control Module (PCM) memory along with the corresponding cylinder numbers for each injector, and an engine performance software map. The PCM recognizes each injector 7-digit code and adapts the operation of each injector to provide similar injection pressures and quantity of delivered fuel for the current operating condition, in accordance with the programmed software map.

The injector body contains a solenoid actuator mounted on the top of the injector. The solenoid is actuated by a supply voltage from the PCM. Upon actuation of the solenoid, a pressure difference is generated within the injector which causes the needle in the injector to move and injection event to occur.

Due to the Bosch common rail fuel system technology and the injector hydraulic chamber, the injectors will operate with a near instantaneous response time to PCM commands. This provides a finer atomization of the injected fuel, and allows the PCM to precisely control the actuation period of the injector. During certain engine operating conditions, each injector is able to deliver a sequence of up to five injections during a single injection cycle. A typical sequence for an injection cycle of five individual deliveries is as follows:

• Two pilot injections
• One main injection
• Two post-injections during the Diesel Particulate Filter (DPF) regeneration phase.

The pilot injection phase is delivered ahead of the main charge of fuel to produce a steady flame front, and create a progressive pressure rise in the cylinder. The pilot injection phase reduces the lag between the injection of fuel and combustion occurring, allowing the remaining charge of fuel to be injected while combustion is taking place. This injection principle can be used to reduce combustion Noise, Vibration and Harshness (NVH) and exhaust emissions.

On vehicles installed with an exhaust system DPF, the High Pressure (HP) fueling system provides a post-injection phase of fuel into the combustion chambers. During the regeneration stage of the DPF, the PCM allows fuel to be injected after the combustion stroke and into the commencement of the exhaust stroke. The post-injection phase causes fuel to burn in the exhaust system, creating high exhaust gas temperatures required to regenerate the DPF.

For additional information, refer to: Electronic Engine Controls (303-14A Electronic Engine Controls - TD4 2.2L Diesel, Description and Operation).

INJECTOR SERVICE INFORMATION

CAUTIONS:

• Do not attempt to remove carbon deposits from the diesel injector nozzle.
• The injector is supplied as a complete assembly. The original injector must not be separated.

NOTE:

The Ingenium I4 2.0L diesel engine cylinders are numbered from the front of the engine. Therefore, No. 1 cylinder and No. 1 injector are located at the front of the engine.

If an injector is removed, the injector must be installed to the original cylinder, and does not require re-programming into the Powertrain Control Module (PCM).

If an injector is renewed, the new injector 7-digit code and corresponding cylinder number must be programmed into the PCM, using an approved diagnostic system.

INJECTOR LEAK-OFF PIPES

1. Injector leak-off port connection
2. Connector fitting/release tab
3. Connector release/locking clip
4. Pressure holding valve

The fuel system leak-off pipes are installed with quick release type couplings, and connect the fuel rail, injectors and HP fuel pump to the fuel filter.

CAUTION:

The injector leak-off pipe must be correctly removed from the injector or the injector will be damaged.

For additional information, refer to: Fuel Injector Fuel Return Line (303-04C Fuel Charging and Controls - INGENIUM I4 2.0L Diesel, Removal and Installation).

The injector leak-off pipe forms a single component, and is provided as a complete assembly. The injector connector consists of one moving part.

HIGH PRESSURE FUEL PIPES

The HP fuel pipes are connected between the High Pressure (HP) fuel pump and fuel rail, and between the fuel rail and the four injectors.

The pipes are single use only, and must be renewed whenever a pipe connection is released.

OPERATION

Fuel injection pressure is generated independently of engine speed and fuel injection events. The High Pressure (HP) fuel system is controllable to the optimum level for smooth operation, and is capable of developing an injection pressure up to 1,800 bar (26,107 psi). The fuel injection timing and volume are calculated by the Powertrain Control Module (PCM) that also energizes the appropriate solenoid-actuated injector.

The fuel system features a pre-injection (pilot) phase to reduce combustion noise and mechanical load. On vehicles installed with a Diesel Particulate Filter (DPF), the fuel system also provides a post-injection phase that is required for regenerating the DPF.

This type of fuel system allows the Ingenium I4 2.0L diesel engine to achieve excellent levels of performance and engine response, while being able to meet current and future exhaust emission legislation.

Fuel charging is achieved with a Low Pressure (LP) and High Pressure (HP) fuel system.

The LP fuel system comprises:

• Fuel tank
• Fuel pump module
• Fuel supply and return lines
• Fuel filter with water in fuel sensor
• Fuel cooler.

The HP fuel system comprises:

• HP fuel pump and fuel metering valve
• Fuel rail with integral fuel rail Pressure Control Valve (PCV) and Fuel Rail
• Pressure (FRP) sensor
• Fuel injectors (4 off)
• HP connecting pipes
• Fuel leak-off pipes.

CONTROL DIAGRAM

NOTE:

A = Hardwired

1. Powertrain Control Module (PCM)
2. Fuel metering valve
3. High Pressure (HP) fuel pump
4. Fuel Pressure Control Valve (PCV)
5. Fuel injector (4 off)
6. Ground
7. Power Supply
8. Fuel Rail Pressure (FRP) sensor

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