SSP 467 - The 4.2 l V8 TDI engine with common rail fuel ...

Service Training

Self-study Programme 467

The 4.2 l V8 TDI engine withcommon rail fuel injection system

Design and Function

2

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The self-study programme portrays the

design and function of new

developments.

The contents will not be updated.

For current testing, adjustment and repair

instructions, refer to the relevant service literature.Important

Note

Following the introduction of the 3.0 l V6 TDI engine

in the Phaeton and Touareg in 2005, the engine

range is now being expanded to include the 4.2 l V8

TDI engine.

Thanks to this range-topping diesel engine,

Volkswagen now has a power plant that boasts

excellent figures and thus superior performance with

250 kw max. at 4,000 rpm and 800 Nm as early as

1,750 rpm.

This high-torque engine, which was developed by

Audi and has featured in the A8 and Q7, has been

adapted for use in the new Touareg. It has been

possible to reach the high emissions goals for the EU5

emissions standard and, at the same time, achieve a

consumption of 9.4 l/100 km with 239 g/km CO2.

This engine sets standards in terms of dynamics,

driving fun, consumption and reliability while

improving comfort and reducing noise.

3

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Engine Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Engine Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Test Yourself . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Contents

4

The 4.2 l V8 TDI engine with common rail injection system

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Engine code CKDA

Type 8-cylinder V engine

Displacement 4,134 cm3

Bore 83.0 mm

Stroke 95.5 mm

Valves per cylinder 4

Compression ratio 16.4 : 1

Max. output in kW 250 at 4,000 rpm

Maximum torque 800 Nm at 1,750 rpmto 2,750 rpm

Engine management Bosch EDC 17

Fuel Diesel fuel complying with DIN EN590

Exhaust gas treatment Exhaust gas recirculation, oxidising catalytic converter, diesel particulate filter

Emissions standard EURO 5

CO2 emission 239 g/km

Introduction

Technical features

● Bosch common rail injection system with piezo

injectors max. 2,000 bar injection pressure

● Diesel particulate filter/oxidising catalytic

converter

● Turbochargers with speed sensors

● Innovative thermal management (ITM)

● Low-temperature exhaust gas recirculation

● Volumetric flow-controlled oil pump

● Demand-regulated fuel delivery unit

● Oil level/oil temperature sender with ultrasonic

measurement principleTo

rqu

e (

Nm

)

Outp

ut (k

W)

Engine speed (rpm)

Output and torque graph

Technical data

5

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Engine Components

Crankshaft drive

The crankcase with a gap of 90 mm between the cylinders (90°V) is made from grey cast iron.

The crankshaft is forged and mounted in 5 bearings. The big end bearing journals are roller burnished for strength.

Roller burnishing is a non-cutting process that uses rolling tools to smoothen and strengthen material surfaces.

The cast aluminium pistons with combustion cavity have a diameter of 83 mm. They are equipped with a ring

carrier cooling duct for cooling the piston. Oil spray nozzles constantly spray oil onto the underside of the piston

crown.

Crankcase

Bearing frame

Oil sump

Crankshaft

Main oil duct

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Engine Components

Chain drive

The chain drive has been taken from the 4.2 l V8 TDI engine as previously used at Audi, but has been improved in

terms of friction and rotational vibration behaviour.

The ancillary components, like the oil pump and coolant pump, are driven via the chain drive D and a gear

module.

Chain drive C

Chain drive B

Chain drive A

Chain drive D

Gear module

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Vibration damper

The 4.2 l V8 TDI engine has been equipped with a vibration damper to dampen the vibrations caused by

combustion. This results in better engine acoustics and less load on the crankshaft.

Counterweight for crankshaft

Rubber track

Belt track

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Engine Components

Design

The exhaust camshaft spur gear is split into two parts

in the left-hand cylinder head. (In the right-hand

cylinder head, the intake camshaft spur gear is split

into two parts.)

The broader part of the spur gear (fixed spur gear) is

positively connected to the camshaft. Six ramps are

located on the front face. The narrower part of the

spur gear (moveable spur gear) can be moved

radially and axially. Recesses for the six ramps are

located on its rear side.

Intermediate disc

Circlip

Moving spur gear

Disc spring

Exhaust camshaft

Backlash compensation

The intake and exhaust camshafts are linked via spur

gear toothing with integrated backlash compensation.

In this case, the spur gear on the exhaust camshaft is

driven by the spur gear on the intake camshaft.

Backlash compensation ensures that the camshafts

are driven with little noise.

Exhaust camshaft

Spur gear on inlet camshaft

Fixed spur gear Fixed spur gear

Ramps

Moving spur gear

Inlet camshaft

Cylinder head (example left)

Spur gearon exhaust camshaft● fixed● moving

Camshaft drive

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Function

Both spur gear parts are pushed together in the axial direction due to the force exerted by a disc spring. At the

same time, they are rotated by the ramps.

This rotational movement offsets the teeth of both spur gear parts and therefore leads to backlash compensation

between the gear wheels on the intake and exhaust camshafts.

Disc spring

Tooth offset

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1

2

34

6

7 8

9

10

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Engine Components

Schematic overview of system

Oil system

Legend

1 - Oil sump2 - Oil pump3 - Oil cooler (coolant)4 - Oil pressure control valve5 - Oil filter module6 - Hydraulic camshaft adjustment7 - Cylinder bank 18 - Cylinder bank 29 - Chain tensioner10 - Piston cooling

Coolant supply

Coolant return

Oil – without pressure

Oil – under pressure

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Volumetric flow-controlled oil pump

The 4.2 l V8 TDI engine uses an oil pump with two pressure levels and volumetric flow control.

This is a vane cell pump that can change its delivery characteristics thanks to an eccentrically mounted adjustment

ring. Engine oil pressure can be applied to the adjustment ring via two control surfaces to turn it against the force

of a control spring. This changes the delivered volume.

The oil pressure is measured at the main oil gallery downstream of the oil filter and, depending on the required

pressure level, oil is sent to one or both control surfaces.

The valve for oil pressure control N428 switches between the two pressure levels depending on the engine load,

engine speed and oil temperature. The drive power of the oil pump is thus reduced considerably, above all, in the

load cycles preferred by customers, like city or long-distance driving.

Oil pump

Vanes

Delivery chamber

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Engine Components

Oil pressure applied from crankshaft oil duct

Control surface 2

Vane cells

Delivery chamber

Valve for oil pressure control N428 – activated

Crankshaftoil duct

Control surface 1

Small delivery quantity

The valve for oil pressure control N428 is supplied with voltage from terminal 15. The valve is connected to earth

via the engine control unit. This opens the oil duct for control surface 2. Oil pressure is always supplied to control

surface 1 via a second oil duct. Now both oil flows act on both control surfaces with the same pressure.

The resulting forces are greater than the force of the control spring. The adjustment ring turns anti-clockwise and

reduces the size of the pump delivery chamber. The small delivery quantity is switched depending on the engine

speed, engine load and oil temperature. This reduces the drive power of the oil pump.

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Oil pressure applied from crankshaft oil duct

Control surface 2

Control surface 1

Vane cells

Delivery chamber

Valve for oil pressure control N428 (zero current) – closed

Large delivery quantity

From an engine speed of 2,500 rpm or an increased torque (full throttle acceleration), the solenoid valve is

disconnected from earth by the engine control unit. The oil duct to control surface 2 is closed. The oil pressure

present only acts on control surface 1. This force is lower than the force of the control spring. The control spring

rotates the adjustment ring clockwise. The adjustment ring is rotated from the centre position and thus enlarges the

delivery chamber between the vane cells. More oil is delivered through the larger delivery chamber. A resistance

acts through the oil holes and the bearing play of the crankshaft against the higher oil volume flow. This causes the

oil pressure to rise. A volumetric flow-controlled oil pump with two pressure levels is achieved in this way.

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Engine Components

Oil level and oil temperature sender G266

An electronic oil level and oil temperature sender is used in the 4.2 l V8 TDI engine for the Touareg.

The conventional oil dipstick has been omitted. The sender works according to the ultrasound principle.

The ultrasonic impulses emitted are reflected by the oil/air boundary layer. Ultrasound is a sound frequency that is

above the range perceivable by humans. The ultrasound waves are reflected depending on the material/density of

the obstacle. Air and oil have different densities. In oil, the sound waves can spread with low resistance. In air, the

dispersion of the sound waves is subject to considerably greater resistance. Therefore the ultrasound waves are

reflected at the oil/air boundary layer.

The advantages of the ultrasound sender are:

● Power consumption < 0.5 A

● Faster sender signal, approx. 100 ms

Measuring unit

3-pole connector housing

Seal

Sender foot with measuring electronics

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Operating principle

Temperature

Filling level

DigitalLogic

Evaluation

Output with pulse-width modulated signal

The sender consists of the sender foot with measuring electronics, the measuring unit and the 3-pole connector

housing.

The ultrasound signals are processed in the measuring electronics. A map is used to calculate the oil level from the

time difference between the sent and reflected signal. In addition to the oil level, the oil temperature is calculated

with a PTC signal. Both values are sent to the dash panel via the engine control unit using a PWM signal (pulse-

width modulation).

The display strategy of the oil level display

is described in self-study programme no. 452

“The 3.0 l V6 245kW TSI engine with

supercharger in the Touareg Hybrid”.

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Engine Components

Exhaust gas recirculation system

Sender for turbocharger speed G688

● Water-cooled VGT turbocharger from Garrett

● High charge pressure in low rev ranges thanks to

optimised compressor wheels

● Variable turbine geometry

● Turbocharger with speed sensors to monitor the

speed of the turbocharger

● Improved software functions in engine control unit

● Better torque and output values

Aperture for speed sensor

Turbocharger with speed sender

● Protection function against excessive speed in

extreme conditions (high elevation/mountain pass

driving)

● Speed reduction when there is a large speed

difference between the two turbochargers

● Turbocharger speed is controlled by evaluation

electronics. The turbine wheel with its guide vanes

gives off a pulse for each vane. Nine pulses of

the turbine wheel represent one revolution of the

turbocharger.

The 4.2 l V8 TDI engine is equipped with two speed-controlled turbochargers.

Features

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Ventilation duct in cylinder head

If there is any leakage around the copper injector

seal, the combustion pressure of 180 bar will allow the

air to escape from the combustion chamber via a

duct. The ventilation duct is located in the cylinder

head above the exhaust manifold.

It prevents the excess pressure from the combustion

chamber reaching the compressor side of the

turbocharger, which could cause faults or damage

seals.

Seal to combustion chamberVentilation duct

Access to crankcase ventilation systemvia the oil chamber in the cylinder head

Piezo injector

Channel for glow plug

Seal

18

Engine Components

The innovative thermal management system (ITM) is being used for the first time in the new VW Touareg. It allows

the flow of heat supplied by the engine to be distributed perfectly between the engine, gearbox and interior.

To distribute the available heat in an ideal way, new software was developed taking the requirements and priorities

of the interior, engine and gearbox into account.

The centrepiece is the so-called thermal manager in the engine control unit. This guarantees a comfortable interior

climate and optimum usage of the available heat to minimise friction in the engine. The air-conditioning and

gearbox control unit signal their heat requirement to engine control unit via the CAN data bus. These are then

weighted together with the engine heat requirement calculated by the engine control unit. The individual ITM

components are then activated by the engine control unit as required.

On the 4.2 l V8 TDI engine, the ITM comprises the following components:

● Standing coolant:

The engine warms up faster during the warm-up phase resulting in lower engine friction and reduction of the

HC and CO emissions. The standing coolant is made possible by an on-demand coolant pump. A vacuum-

operated control shutter is pushed over the coolant pump impeller. The coolant pump continues to be driven,

but coolant is not pumped. When the vacuum is removed, the control shutter is opened by a set of springs.

● Cylinder head temperature sensor:

A coolant temperature sensor is used in the cylinder head close to the combustion chamber to monitor the

critical valve bridge temperature and to avoid boiling coolant during the standing coolant mode. The coolant

pump is activated using a load/engine speed-dependent map to protect components when there are large load

jumps.

● Gearbox oil heating:

Immediately after the coolant pump is switched on, the coolant that has already been heated up in the small

engine circuit is made available to the gearbox oil cooler via an electrically operated directional valve. The

faster heating up of the gearbox oil also reduces frictional losses in this area during the warm-up phase.

● Heating shut-off:

If no heating is required, the complete thermal capacity of the interior heating can be switched off. As a result,

the engine does not have to provide heat during the warm-up phase.

Innovative thermal management

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Thermal management – schematic diagram

The schematic diagram shows in a simplified manner how the “Innovative Thermal Management” system works.

The heat produced by the engine is utilised in an ideal way and is passed onto the interior climate control and the

gearbox as required. The individual components signal their heat requirement to the engine control unit and the

components are activated depending on the priority.

InteriorGearboxCylinder head

Electrical pump

Engine block

Maincoolantpump

Thermostat

Mainradiator

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Engine Components

Coolant circuit

Impeller

Rolling diaphragm

Ring piston

Vacuum connection

By-pass seal

Friction bearing

Rod seal

Guide rod

Control shutter

On-demand coolant pump

The “Innovative Thermal Management” system used with the 4.2 l V8 TDI engine makes use of an on-demand

coolant pump.

Standing coolant

When the engine is cold, the on-demand coolant pump stops the circulation of the coolant.

This state is called standing coolant. The coolant circuit solenoid valve N492 pushes a vacuum-operated control

shutter over the spinning vane rotor in the coolant pump. This stops the circulation of coolant. The coolant heats up

more quickly and shortens the engine warm-up phase considerably. The heated coolant is sent to the automatic

gearbox to also actively heat it. Heating the engine and gearbox oil more quickly reduces internal friction. This

reduces the consumption and CO2 emissions.

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Rolling diaphragmReturn spring

Control shutterThermostat opens from a coolant temperature of 87 °C

Circulating coolant

When no vacuum is applied, the control shutter is pressed into its resting position by return springs inside the

coolant pump. The coolant circulates and heats the thermostat to activate the large cooling circuit.

This ensures circulation of the coolant at all times (fail-safe).

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Engine Components

Low-temperature exhaust gas recirculation

The low-temperature exhaust gas recirculation system is used to minimise nitrogen oxide (NOx), which is formed

when diesel fuel is burnt.

The pump for exhaust gas recirculation cooler V400 is activated immediately upon engine start.

The temperature in the exhaust gas recirculation cooler is regulated to 55°C by the thermostat.

EGR valve cylinder bank 2

Thermostat for exhaust gas recirculation cooling

EGR cooler with bypass valve

EGR valve cylinder bank 1

Pump for exhaust gas recirculation cooler V400

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The pump for exhaust gas recirculation cooler V400 supplies the low-temperature circuit with cold coolant directly

from the main radiator. The pump is activated immediately upon engine start.

The EGR cooler is integrated in its own low-temperature cooling circuit. It is no longer part of the small engine

cooling circuit.

Advantages

● Considerable increase in cooling performance

● Independent EGR cooling is also possible during the warm-up phase

The EGR valves regulate the exhaust gas recirculation rates. A differential pressure sender is also fitted in the EGR

valve. The differential pressure sender measures the pressure on the intake side.

The value from the differential pressure sender and the value from the air mass meter are processed in the engine

control unit. The differential pressure sender has been added because, due to the design, the air mass meter is

quite far away from the actual cylinder inlet.

In extreme engine load conditions, engine running faults could result if only the value from the air mass meter is

available. The engine control unit works with both values to avoid this.

This guarantees a stable measuring value for the intake air across all engine-speed and torque ranges.

Advantages

● More exact measured values

● Faster regulation is possible

● Almost same pressure and load relationships on both cylinder banks

If the differential pressure sender signal fails, an entry is made in the fault memory and the engine control unit

works with the value from the air mass meter.

Differential pressure sender

EGR valve (cylinder bank 1)

EGR valve (cylinder bank 2)

Differential pressure sender

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1

2

11

Engine Components

Low-pressure fuel system

Fuel system

The fuel system is divided into three pressure areas

● High pressure up to 2000 bar

● Return pressure from the injectors 10 bar

● Supply pressure, return pressure

In the fuel supply system, the fuel is delivered by the

fuel delivery unit from the fuel tank through the fuel

filter to the high-pressure pump as required. The fuel

delivery unit supplies the fuel pressure as required.

The engine control unit calculates the current fuel

requirement from the accelerator position, torque,

engine temperature etc. and sends a corresponding

signal to the fuel pump control unit. The fuel pump

runs fast or slow accordingly.

The high fuel pressure required for injection is

generated in the high-pressure pump and is fed into

the high-pressure accumulator (rail).

The fuel reaches the injectors from the high-pressure

accumulator. The pressure retention valve in the

overflow diesel oil line maintains the injector return

pressure at 10 bar. This pressure is important for

operation of the piezo injectors.

1 - Fuel delivery unit GX1

2 - Pressure-resistant fuel filter

3 - Fuel temperature sender G81

Calculates the current fuel temperature.

4 - High-pressure pump

Generates the high fuel pressure required for

injection.

5 - Fuel metering valve N290

Controls the quantity of fuel to be pressurised as

required.

6 - Pressure retention valve

Maintains the return pressure of the injectors at

approx. 10 bar. This pressure is required for the

injectors to work.

High pressure

Supply pressure

Return pressure

Return from the injectors

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7

10

5

4

6

8

9

12

123

10

10 - Injectors

11 - Fuel pump control unit J538

12 - High-pressure accumulator (rail)

Stores the fuel required for injection into all cylinders

under high pressure.

7 - Engine control unit J623

8 - Fuel pressure sender G247

Measures the current fuel pressure in the high-

pressure area.

9 - Fuel pressure regulating valve N276

Sets the fuel pressure in the high-pressure area.

Cylinder bank 1

Cylinder bank 2

26

Fuel delivery unit GX1

The fuel pump is an electrically driven annular gear pump and produces a fuel pressure of 3.5 to 6 bar at a

maximum of 220 l/h.

The fuel pressure is regulated according to requirements.

Function

The engine control unit calculates the current fuel requirement from the accelerator position, torque, engine

temperature etc. and sends a PWM signal to the fuel pump control unit J538. The fuel pump control unit is mounted

on the fuel tank.

The control unit sends a corresponding command (signal) to the fuel pump.

As a result, the fuel pump runs faster or slower and supplies the requested volume of fuel.

Thanks to the fuel pump being activated on demand, an additional pre-supply pump is no longer required and has

been omitted.

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Engine Components

Fuel supply system

Fuel pump

Fuel delivery unit

Electrical connection

Fuel return

Fuel line for auxiliary heating

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Functional diagram

Legend

GX1 Fuel delivery unit

G1 Fuel gauge

G3 Coolant temperature gauge

J285 Control unit in dash panel insert

J538 Fuel pump control unit

J623 Engine control unit

K29 Glow period warning lamp

K132 Electronic power control fault lamp

K231 Diesel particulate filter warning lamp

Input signal

Output signal

Positive

Ground

CAN data bus

CAN data bus

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Engine Components

Basic explanation

The 4.2 l V8 TDI engine in the Touareg is equipped

with a Bosch common rail injection system for mixture

preparation.

In this system, pressure generation and fuel injection

are separate. The high-pressure pump generates the

high fuel pressure required for injection.

Common rail fuel injection system

The common rail fuel injection system is controlled by

the Bosch EDC 17 engine management system.

● The injection pressure is instantly available and is

adapted to the current engine operating status

● Flexible fuel injection process, with several pilot

and secondary injection processes.

Injectors

Injectors

Fuel pressure regulating valve N276

High-pressure accumulator (rail)cylinder bank 1

High-pressure accumulator (rail)cylinder bank 2

High-pressure pump

Fuel metering valve N290

Fuel line to high-pressure accumulator (rail)

Fuel pressure sender G247

Fuel distributor between the rails

29

Restrictors in the rail

When the injector is closed and during subsequent

injections, a pressure wave from the injector is built

up. This continues up to the rail and is reflected from

there again.

To dampen the pressure waves, restrictors are fitted

in the fuel supply from the high-pressure pump to

the high-pressure accumulators (rails), on the high-

pressure accumulators (rails) for cylinder banks 1

and 2 and in the rails in front of each injector.

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The correct tightening torque must be used

when tightening the injector fuel line and

also the line connecting the two rails.

Deformed or damaged high-pressure

lines may not be used again – they have

to be replaced.

High-pressure line

Union nut

Restrictor

Rail

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Engine Components

Design of high-pressure pump

Pump plunger

Intake valve

Outlet valve

Connection to rail

Fuel inlet

Fuel return

Overflow valve

Drive shaft

Roller

Plunger spring

Drive cam


High-pressure pump

The high-pressure pump is a 2-piston pump. The pump is driven by a toothed belt.

It generates the high fuel pressure of up to 2000 bar that is required for injection.

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Outlet valve

Intake valve


Fine filter

Overflow valve

Fuel return

Fuel inlet

Drive shaftwith cam

Roller

Pump plunger

Connection to rail

Plunger spring

Design of high-pressure pump – schematic

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Engine Components

High-pressure fuel system


The fuel metering valve N290 is integrated into the high-pressure pump. The valve regulates the fuel quantity that

is required to produce high pressure.

The advantage of this is that the high-pressure pump only has to pressurise the amount of fuel that is required for

the current operating conditions. This reduces the power consumption of the high-pressure pump and avoids

unnecessary fuel heating.

Function

When no current is supplied, the fuel metering valve is open. To reduce the quantity flowing to the compression

chamber, the valve is actuated by the engine control unit with a pulse-width modulated (PWM) signal.

The fuel metering valve is pulsed closed by the PWM signal. The quantity of fuel flowing into the compression

chamber of the high-pressure pump varies in relation to the PWM signal.

Inlet from inside of pump

To compression chamber

Control plunger

33

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The fuel pressure regulating valve is located on the

high-pressure accumulator (rail) for cylinder bank 1.

The fuel pressure is set in the high-pressure area by

opening and closing the regulating valve.

To do this, the regulating valve is actuated by the

engine control unit with a pulse-width-modulated

signal.

Design

High-pressure accumulator (rail)

Valve needle

Solenoid

Return to the fuel tank


Valve armature

Valve spring


High-pressure accumulator (rail)- cylinder bank 1

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Engine Components

Function

Regulating valve in resting position (engine “off”)

If the regulating valve is not actuated, the pressure

regulating valve is opened by the valve springs.

The high-pressure area is connected to the fuel return

line.

This ensures a volume balance between the fuel high-

pressure and low-pressure area. Vapour bubbles,

which can form in the high-pressure accumulator (rail)

during the cooling process after the engine is

switched off, are avoided and the starting behaviour

of the engine is thus improved.

Regulating valve actuated (engine "on")

To attain an operating pressure of 230 to 2,000 bar

in the high-pressure accumulator, the regulating valve

is actuated by the engine control unit J623 using a

pulse-width modulated (PWM) signal. This creates a

magnetic field in the solenoid. The valve armature is

attracted and presses the valve needle into its seat.

The fuel pressure in the high-pressure accumulator is

therefore opposed by a magnetic force. Depending

on the on-off ratio of actuation, the flow to the return

line and therefore the quantity flowing back is varied.

This also enables pressure fluctuations in the high-

pressure accumulator to be compensated for.

Effects upon failure

The engine will not run if the fuel pressure regulating valve fails because it is not possible to build up sufficient fuel

pressure for fuel injection.

Engine control unit J623

Valve springs

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Regulation of the high pressure fuel by the fuel pressure regulating valve N276

Regulation of the high-pressure fuel by the fuel metering valve N290

Regulation by both valves

Regulation of the high-pressure fuel

In the common rail injection system, the high-pressure fuel is regulated with a so-called dual-regulation design.

The fuel pressure regulating valve N276 and the fuel metering valve N290 are actuated by the engine control unit

using a pulse-width modulated signal (PWM signal) for this purpose.

Depending on the operating status of the engine, the high fuel pressure is regulated by one of the two valves. The

other valve is then only controlled by the engine control unit.

Regulation by the fuel pressure regulating valve N276

When the engine is started and the fuel needs warming,

the high fuel pressure is regulated by the fuel pressure

regulating valve N276. To warm up the fuel quickly, the

high-pressure pump delivers and pressurises more fuel

than is required. The excess fuel is returned to the fuel

return line by the fuel pressure regulating valve N276.

Regulation by the fuel metering valve N290

When there are large injection quantities and high

rail pressures, the high fuel pressure is regulated by

the fuel metering valve N290. This results in on-

demand control of the high fuel pressure. The power

consumption of the high-pressure pump is reduced

and unnecessary fuel heating is avoided.

Control by both valves

During idling and overrun and when there are small injection quantities, the fuel pressure is regulated by both

valves at the same time. This allows precise regulation, which improves the idling quality and the transition to

overrun.

Schematic diagram of dual-regulation design

Inje

ctio

n q

ua

ntity

Engine speed

36

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Engine Components

Injectors

Piezo-controlled injectors are used in the common rail

injection system for the Touareg 4.2 l TDI engine. The

injectors are controlled via a piezo actuator.

This results in the following advantages:

● Very short switching times

● Several injections per working cycle are possible

● Precise proportional injection quantities

Piezo actuator

Nozzle needle

Pin-type filter


Fuel inlet(high-pressure connection)

Fuel return

Connecting plunger

Valve plunger

Valve plunger spring

Switching valve Restrictor plate

Seal

Nozzle spring

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Pilot injection

A small quantity of fuel is injected into the combustion

chamber prior to main injection. This leads to a rise in

temperature and pressure in the combustion chamber.

The main injection ignition time lag is therefore

shortened, thereby reducing the rise in pressure and

pressure peaks in the combustion chamber.

The results are low combustion noise and low exhaust

gas emissions.

The number, time and injection quantities of the pilot

injection processes are dependent on the engine

operating status.

When the engine is cold and at low engine speeds,

two pilot injections are carried out for acoustic

reasons.

At higher loads and engine speeds, only one pilot

injection is carried out in order to reduce exhaust

emissions.

No pilot injection is carried out at full throttle and

high engine speeds because a large quantity of fuel

has to be injected to achieve a high level of efficiency.

Main injection

Following pilot injection, the main injection quantity

is injected into the combustion chamber following a

brief injection pause.

The injection pressure level remains virtually constant

throughout the entire injection process.

Secondary injection

Two secondary injection processes are carried out to

regenerate a diesel particulate filter. These secondary

injections increase the exhaust gas temperature,

which is necessary to combust the soot particles in the

diesel particulate filter.

Injection process

The very short switching times of the piezo-controlled injectors allow flexible and precise control of the injection

phases and injection quantities. As a result, the injection process can be adapted to the relevant operating

requirements of the engine. Up to five partial injections can be carried out per injection process.

Initialisation voltage (V)

Injection (rate of injection)

Pilot injection

Main injection

Time

Secondary injection

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Air mass meter G70

System overviewSensors

Pow

ert

rain

CA

N d

ata

bus

Glow period warning lamp K29

Charge pressure sender G31Intake air temperature sender G42

Engine speed sender G28

Coolant temperature sender G62

Oil temperature sender G8

Fuel temperature sender G81

Fuel pressure sender G247

Radiator outlet coolant temperature sender G83

Hall sender G40

Exhaust emissions warning lamp K83

Diesel particulate filter warning lamp K231

CA

N

LOW

CA

N

HIG

H

Control unit in dash panel insert J285

Engine control unit J623 (master)

Engine control unit J623 (slave)

Elevation sender

Exhaust gas tem-perature sender 1 for bank 2 G236

Air mass meter 2 G246

Exhaust gas tem-perature sender 3 for bank 2 G497

Catalytic converter check temperature sensor 2 G29

Lambda probe 2 G108

Exhaust gas pressure sensor 2 G451

Accelerator position sender G79Accelerator position sender 2 G185

Exhaust gas pressure sensor 1 G450

Exhaust gas temperature sender 1 G235

Lambda probe G39

Catalytic converter temperature sensor 1 G20



Oil level and oil temperature sender G266

Brake light switch F

Engine Management

39

S467_017

Actuators

Diagnostic connector T16

Injectors for cylinders 1, 4, 6, 7 N30, N33, N84, N85

Automatic glow period control unit J179/Glow plugs for cylinders 1, 4, 6, 7 Q10, Q13, Q15, Q16


Throttle valve module J338

Intake manifold flap motor V157

Exhaust gas recirculation control motor V338


Exhaust gas recirculation cooler changeover valve N345

Engine component current supply relay J757

Fuel pump control unit J538Fuel delivery unit GX1

Lambda probe heater Z19

Coolant circulation pump V50

Pump for exhaust gas recirculation cooler V400

Turbocharger 1 control unit J724Turbocharger 2 control unit J725

Injectors for cylinders 2, 3, 5, 8 N31, N32, N83, N86

Lambda probe heater 2 Z28

Intake manifold flap 2 motor V275

Glow period control unit 2 J703/glow plugs for cylinders 2, 3, 5, 8 Q11, Q12, Q14, Q17

Exhaust gas recirculation control motor 2 V339

Throttle valve module 2 J544

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Service

Designation Tool Application

T40094 Camshaft fitting

tool

T40094/1 Mount

T40094/2 Mount

T40094/9 Mount

T40094/10 Mount

T40094/11 Cap

T40094/12 Mount

For removing and fitting the

camshafts


tool

For removing and fitting the

camshafts

S467_062

S467_063

Special tools

41

Designation Tool Application


tool

For fitting the camshafts

T40178 Oil gauge tester For checking the oil level when

there are system errors

S467_064

S467_065

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Test Yourself

Which answers are correct?

One or several of the given answers may be correct.

1. Which statement about the oil pump is correct?

a) The oil pump works with only one pressure level.

b) The oil pump can change its delivery characteristics via an eccentrically mounted adjustment ring.

c) The oil pump generates up to 4 pressure levels depending on the load.

2. Which statement about the oil level and oil temperature sender G266 is correct?

a) The sender operates according to the Hall principle.

b) The sender uses the heat conduction method.

c) The sender operates according to the ultrasound principle.

3. What is the advantage of the innovative thermal management system?

a) The heat produced by the engine is distributed optimally among the components.

b) The heat produced by the engine is always passed on first to the gearbox.

c) The heat produced by the engine is always passed on first to the interior heating.

4. Where is the fuel pressure in the low pressure area of up to 6 bar regulated on the 4.2 l V8 TDI?

a) In the high-pressure pump

b) In the pre-supply pump

c) In the fuel delivery unit

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5. What is the purpose of camshaft spur gear backlash compensation?

a) Backlash compensation ensures that the camshafts are driven with little noise.

b) Backlash compensation ensures that the intake camshaft is adjusted at high engine speeds.

c) Backlash compensation ensures rigid engine speed compensation between the gears on the intake and

exhaust camshafts.

6. Which statement about the turbocharger with speed sender is correct?

a) Lower torque and output values

b) Speed reduction when there is a large speed difference between the two turbochargers

c) Fixed turbine geometry

Answers

1. b); 2. c); 3. a), b); 4. c); 5. a); 6. b)

© VOLKSWAGEN AG, Wolfsburg

All rights and rights to make technical alterations reserved.

000.2812.39.20 Technical status 07.2010

Volkswagen AG

After Sales Qualifizierung

Service Training VSQ-1

Brieffach 1995

D-38436 Wolfsburg

❀ This paper was manufactured from pulp bleached without the use of chlorine.

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SSP 467 - The 4.2 l V8 TDI engine with common rail fuel ...

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