SSP_920493

The Audi 4.0l V8 TFSI engine
from the EA825 series
eSelf Study Program 920493
Audi of America, LLC
Service Training
Created in the U.S.A.
Created 2/2020
Course Number 920493
©2020 Audi of America, LLC
All rights reserved. Information contained in this manual is based on the
latest information available at the time of printing and is subject to the
copyright and other intellectual property rights of Audi of America, LLC.,
its affiliated companies and its licensors. All rights are reserved to make
changes at any time without notice. No part of this document may be
reproduced, stored in a retrieval system, or transmitted in any form or by
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nor may these materials be modified or reposted to other sites without
the prior expressed written permission of the publisher.
All requests for permission to copy and redistribute information should be
referred to Audi of America, LLC.
Always check Technical Bulletins and the latest electronic service repair
literature for information that may supersede any information included in
this booklet.
The eSelf-Study Program (eSSP) teaches a basic understanding of the design and mode of operation of new models, new
automotive components or new technologies.
It is not a repair manual! Figures are given for explanatory purposes only and refer to the data valid at the time of
preparation of the SSP.
For further information about maintenance and repair work, always refer to the current technical literature.
Release Date: February 2020
2
Introduction
Engine description and special features 
Technical data 
Engine mechanics
Cylinder block 
Crankshaft 
Cylinder head 
Camshaft drive configuration 
Crankcase ventilation system 
Positive Crankcase Ventilation (PCV) 
Fuel tank ventilation 
Vacuum system 
Oil supply
Oil circuit overview 
Oil pump 
Piston cooling 
Sensors and actuators 
Oil filter and oil-coolant heat exchanger 
Oil filter module 
Oil supply in the cylinder head cover 
5
6
7
8
8
12
18
31
36
41
42
44
46
46
48
50
51
53
54
55
Drive for ancillaries
56
Cooling system
58
System overview 
Coolant circuit in cylinder block 
Cooling concept for the cylinder head 
Transmission coolant circuit 
Air supply
Overview of air ducts 
Intake manifolds 
Throttle Valve Control Modules GX3 and GX4 
Turbocharging
Twin scroll exhaust manifold 
Twin scroll turbochargers 
Turbocharger mounting 
Turbocharger oil and coolant connections 
Heat shield in inner V of engine 
58
60
62
67
69
69
71
72
73
73
74
76
77
78
Exhaust system
79
Fuel system
80
High-pressure injector 
Engine management
System overview 
Engine Control Module 
Inspection and maintenance
Service information and operations 
Special tools and workshop equipment 
Knowledge assessment
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82
82
84
85
85
86
87
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4
Introduction
The new Audi V8 engine from the EA825 series is a joint
development of Porsche and AUDI AG. The engine construction is based on the V6 engine from the EA839 series. This
has advantages not only for the manufacturing process; the
close relationship has benefits for after sales service as
well. For example, many of the special tools can be used for
both engines.
The new V8 engines were first introduced by two other
Group brands: Bentley and Porsche. At Audi, the new V8
will be installed first in the A8.
The engines are manufactured in the new Porsche engine
production facility in Zuffenhausen.
676_153
Learning objectives of this eSelf-Study Program:
This eSelf-Study Program describes the function of the 4.0l
V8 TFSI engine of the EA825 engine series. Once you have
completed this eSelf-Study Program, you will be able to
answer the following:
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What are the technical characteristics of the engine?
How do the oil supply and engine cooling systems work?
What are the special features of the air supply system?
What effect does the improved injection system have?
What has changed for after-sales service and maintenance?
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Engine description and special features
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Eight-cylinder V-engine with 90° bank angle
Aluminum cylinder block
Chain drive valve timing
Four valves per cylinder, double overhead camshafts (DOHC),
roller cam followers, variable valve timing
Turbochargers with charge air cooling (maximum charge
pressure: 31.9 psi [2.2 bar] absolute)
Emission control system with pre and main catalytic
converter system, Oxygen sensors
High-pressure and low-pressure fuel systems
(controlled according to demand)
Cylinder on Demand (CoD)
Indirect charge air cooling system
Fully electronic direct injection with electric throttle
Adaptive Oxygen sensor control
Mapped ignition with single ignition coils
Cylinder-selective adaptive knock control
Thermal management system
Advantages over the previous version V8 from the EA824 family:
› High torque at low rpm
› Improved responsiveness
› Significant increase in efficiency
› Increased power output and torque
› Better fuel economy
› Meets the relevant country-specific emission standards
› Thermal management system (new cooling module)
› Reduced engine friction
› Improved injection system
Highlights of the new V8 engine
Crankcase (optimized for weight) with
APS-coated cylinder running surface
Thermal management
Friction-optimized
valve gear
Fuel system with
central injector
configuration
Cylinder head design with
valve lift and Cylinder on
Demand
“Hot Side Inside” (HSI)
turbocharging system
676_002
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Technical data
Torque-power curve of 4.0l V8 FSI engine
(engine code CXYA)
486.79 lb ft
(660 Nm) at
1850 - 4500
453.26 hp
(338 kW)
at 5500
Diagram: engine at full load
	  Power output in kW
	  Torque in Nm
676_003
Features
Specifications
Engine code
CXYA
Design
8-cylinder engine with 90° V angle
Capacity
243.85 cu in (3996 cm)3
Stroke
3.38 in (86.0 mm)
Bore
3.38 in (86.0 mm)
Cylinder spacing
3.22 in (82.0 mm)
Number of valves per cylinder
4
Firing order
1-3-7-2-6-5-4-8
Compression ratio
11.0 : 1
Power output at rpm
453.26 hp (338 kW) at 5500
Torque at rpm
486.79 lb ft (660 Nm) at 1850 - 4500
Fuel
Premium unleaded
Turbocharging
“Hot Side Inside” (HSI) turbochargers with charge air cooling
(maximum charge pressure: 31.9 psi [2.2 bar] absolute)
Engine management
Bosch MG1CS008
Engine weight
509.2 lb (231 kg)
Emission control
Dual exhaust system with pre-catalytic converter and 3-way catalytic converter
Emission standard
ULEV125, (Pr. number:7MU)
Firing order during changeover to
4 cylinder operation (cyl. 2, 3, 5, 8
shut off)
1-7-6-4
7
Engine mechanics
Cylinder block
The aluminum (ALSi9Cu3) cylinder block is single sand cast unit. It is a “deep skirt” design. This means the individual cylinder walls reach down as far as the upper oil sump providing a very high degree of rigidity. The entire cylinder block including
the bearing covers and corresponding bolts weighs 86.2 lb (39.1 kg).
In addition to the oil and cooling passages, the following
components and assemblies are integrated with or
installed on the cylinder block:
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The engine number is engraved on a plate on the front of
the engine below cylinder bank 1. There is also a sticker
with the engine code and serial number attached to the
vacuum pump cover.
Oil spray jets
Water pump intermediate shaft
Oil pump
Oil cooler
Coolant pump
Engine mounting
Mounting points for ancillary components
676_004
8
Atmospheric plasma spraying (APS)
To create a sufficiently robust iron running surface, the
cylinder walls are first roughened with a special milling tool
which cuts a dovetailed pattern into the cylinder. The
resulting undercuts ensure that the APS coating adheres
properly.
A rotating plasma torch is then inserted into the cylinder.
An arc discharge is used to create a plasma into which a
powdered coating material is blown using compressed air.
The powder melts and is sprayed onto the rough cylinder
wall. There it solidifies and fills the undercuts thus creating
a wear layer.
A layer of iron (roughly equivalent to 100Cr6 bearing steel)
is applied in several layers in approximately 30 seconds.
The final thickness is approximately 150 micrometers.
(One micrometer equals one millionth of a meter.)
Application of plasma coating
676_005
Wear layer on cylinder wall
Cylinder block
676_006
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Crankshaft bearings
The upper crankshaft bearing bosses are integral with the
cylinder block. The grey cast iron bearing caps are retained
with longitudinal and transverse bolts.
Grey cast iron bearing cap
Crankshaft bearing shell (bottom)
Crankshaft bearing shell (top)
Hole for locking pin T40069
(with engine removed)
Transverse bolt for cross-bolting
the crankshaft bearing caps.
676_007
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Sump (top section)
Timing chain cover
The top section of the sump is made of an aluminum die
cast alloy. Dowel pins are used to ensure exact positioning
during assembly.
This die-cast component is made of an aluminum alloy; if it
needs to be removed, it can be pressed off the cylinder
block using auxiliary bolts. The engine speed sensor as well
as the crankshaft oil seal are located in the cover.
Sump (bottom section)
Sealing flange (pully end)
The bottom section of the sump is made of an aluminum
sheet metal. The oil drain plug and the oil level/oil temperature sensor are integrated with it.
This component is also made of an aluminum alloy. It
provides the attachment point for the dipstick tube and the
crankshaft oil seal.
Cylinder 1
Oil seal
Oil ring
Sealing flange
Pulley end
Timing chain
cover
Engine number
Oil baffle plate
Oil pan top section
Oil pan bottom section
Oil drain plug
Oil Level Thermal Sensor
G266
676_008
Note
Housing cover and sumps are sealed by a liquid gasket (see ElsaPro for details).
11
Crankshaft
The forged steel crankshaft is supported by five main
bearings to ensure a smooth running engine.
The cylinder banks are positioned at a 90 degree angle to
one another with connecting rods of the cylinders opposite
of each other sharing the same bearing journal.
676_009
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Crankshaft bearings
The IROX bearings conform to the high demands of hybrid
drive and start/stop operation.
Three-layer bearing construction:
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The steel backbone provides the required stability.
The second layer is made of a soft metal carrier substrate to
which the third layer is fixed.
The third layer consists of a polymer base with a homogeneous
distribution of filler materials which ensure the best possible
running and wear characteristics.
Crankshaft bearing
shell (top)
Timing gear
(drive gear)
Crankshaft bearing 1
(pulley end)
Chain sprocket
(drive gear for oil
pump)
Crankshaft bearing
shell (bottom)
676_010
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Thrust washers
Four thrust washers (top and bottom) are installed on
crankshaft bearing four to control longitudinal movement
of the crankshaft. The oil grooves of the thrust washers
face towards the crankshaft.
Crankshaft bearing four
Thrust washer (bottom)
Thrust washer (top)
Crankshaft bearing shell
(top)
676_013
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Piston
To minimize noise, the cast pistons are mounted at a 0.5 mm offset towards the pressure side (see illustration 676_016
below). Due to the compression and valve timing, intake valve recesses of different sizes are integrated in the piston crown
(intake valve: large; exhaust valve: small). The chamber walls on the piston pressure side are narrower than on the counter-pressure side which is subject to less strain. The high rigidity of the pressure side makes it possible to achieve a defined
piston wear pattern while optimizing the load. On the counter-pressure side, the piston is much softer and can adapt better
to the shape of the cylinder. This combination results in different pistons for cylinder bank 1 (right bank) and cylinder bank 2
(left bank).
Piston rings
1. Top piston ring (compression ring) mounted in the ring carrier, rectangular section seal
2. Taper-faced ring
3. Oil scraper ring (3 parts)
Piston pins
The steel alloy piston pins are coated and hardened. Each piston pin measures 22 mm in diameter.
Note
The small valve recesses always face the inner V.
676_014
Piston pressure side
Counter-pressure side
Counter-pressure side
Piston pressure side
676_016
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Connecting rods
The cracked trapezoidal connecting rods are made of high-strength steel. The bushing in the upper connecting rod small
end is made from a copper alloy (CuNi9Sn6). The connecting rod bearings are 22.3 mm wide. Both bearing shells are
identical. The bearings are made of three materials: a steel substrate, a bismuth-bronze alloy intermediate layer and a thin
bismuth crystal lining. The connecting rods are installed at an offset to the engine’s longitudinal axis.
676_017
Installing the connecting rods
It is important to install the connecting rods in the correct position. The points of the two installation markings must be in
line with one another (see illustration 676_018 ). Only connecting rods of the same weight class may be installed on a
given engine.
Installation marking
View showing data matrix code
XX = weight class of large connecting rod eye
YY = weight class of small connecting rod eye
676_018
676_019
Note
Do not interchange bearing shells during installation; if new components are installed the specifications for
clearance tolerances must be observed (see Elsa Pro for details).
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Belt pulley / vibration damper
A single bolt secures the pulley/vibration damper to the crankshaft, and a dowel pin locates them in the correct position.
A diamond-coated washer is installed between the vibration damper and the end of the crankshaft as a locating element.
The housing of the viscous vibration damper is made of forged steel, while the inertia ring is manufactured out of
aluminum. This provides the greatest possible strength against deformation caused by centrifugal force.
Diamond-coated friction
washer
Pulley
Crankshaft speed detection
676_020
Engine Speed Sensor G28 is located in the timing chain cover. It detects signals from the magnetic ring on the drive plate.
Magnetic ring
Carrier plate
Engine Speed Sensor
G28
676_021
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Cylinder head
The cylinder heads have the following technical features:
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DOHC, 4 valves per cylinder.
Roller cam followers.
Integral exhaust manifold.
“Hot Side Inside” (HSI).
Direct injection combustion process with central injector position.
Audi valvelift system (AVS). Enables Cylinder on Demand (CoD) operation.
Intake valves: hardened and tempered.
Exhaust valves: hardened and tempered, sodium-filled hollow stems.
676_023
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Noise insulation
The two-part insulating mats over the cylinder head covers help reduce noise. This provides effective insulation against
high-frequency ticking noises greater than 2500 Hz from the injectors and the high-pressure fuel pumps.
676_044
Note
Pay close attention to the installation order of components on the cylinder heads. Some components may be
located under the insulating mats and can no longer be installed after the mats have been installed.
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Cylinder head cover attachments
Camshaft adjuster
Ignition coils
Hall sender
Cylinder head cover
(right-side)
Camshaft control valves
(solenoid)
676 _045
Timing chain case cover
Cylinder head gasket
A three-layer metal gasket is used. It is only available in one thickness.
Cylinder head gasket
676 _024
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Valve gear
1
10
9
2
8
3
7
6
4
5
676 _025
Legend
1.
2.
3.
4.
Roller cam followers with supporting element
Exhaust valve spring
Twin-lip valve stem oil seal
Exhaust valve
Bi-metal valve with sodium filling and chromium-plated
valve stem ends
5. Inlet valve
Monometallic valves with inductive hardened valve seats
6. Valve spring plate (bottom)
7. Single-lip valve stem oil seal
8. Inlet valve spring
9. Upper valve spring plate
10. Valve keepers
The valve springs are a simple cylindrical shape.
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Camshaft housings
The camshaft housings of both cylinder banks work in the
same way; the only difference is the location of certain
components. The camshaft housing for cylinder bank 2 is
described here as an example. The cylinder head is sealed
by a liquid gasket and a rubber molded gasket.
The camshafts are mounted in five sleeve bearings in the
camshaft housing. The center bearing is constructed
additionally as an axial bearing. The ignition coils, cam
actuators for Cylinder on Demand, Hall sensors for
camshaft position detection, high pressure fuel pump,
injectors, fuel rail and oil separator for the crankcase
breather system are also installed.
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1
10
2
3
4
7
5
6
8
9
676_026
Legend
1. Cylinder head cover
2. Retention valve
3. Dowel sleeves
4. Seal
5. Camshafts
6. Control valve for camshaft adjuster
7. Axial bearing
8. Bearing cap
9. Bolted connection for camshaft bearing
10. Sealing plug
11. Plug
12. Bolted connection for cylinder head cover
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Identification number of matched pair for camshaft housing and camshaft bearing
The following applies to the bearing caps:
E for intake side and A for exhaust side; bearing
position number 1 to 5 starting at the front.
676_027
Identification number of matched pair for camshaft housing and cylinder head
The following applies to the camshaft bearing caps:
E for inlet side and A for exhaust side; bearing position
number 1 to 5 starting at the front. The identification
number for the matched pair is given underneath. The
three-digit numbers on the bearing caps (see marking)
must match the last three digits of the four-digit number
on the camshaft housing.
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This identification number matches each bearing cap to a
specific cylinder head.
It is important to ensure correct allocation during assembly.
The two four-digit numbers must be the same: XXXX = XXXX.
Camshaft housing
Cylinder head
676_029
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Camshafts
All four camshafts are composite camshafts comprising a
basic shaft with pressed-on end pieces. The cam elements
are installed onto the splines on the shaft. Two cam elements are fixed in position; the other two are moveable.
The moveable cam elements have two cam profiles for each
valve. This provides the operational basis for the Cylinder
on Demand (CoD) system.
The high-pressure fuel pumps are driven by the exhaust
camshafts via four-lobe cams. In addition, each camshaft
has a sender wheel used for detecting the camshaft position.
The bearings for the camshafts are located in the basic
shaft. A groove for the axial bearing is located in the center
of the camshaft.
676_030
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Camshaft components
8
7
1
7
6
2
5
3
4
676_031
Legend
1.
2.
3.
4.
5.
6.
7.
8.
Basic shaft
Bearing caps
Ball-and-spring locking mechanism
Control valve for camshaft adjuster
Shaft stub with four-lobe cams for driving the high-pressure fuel pump
Cam elements, moveable for the Cylinder on Demand system
Cam elements
Sender wheel
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Cylinder on Demand (CoD)
The EA825 engine is equipped with a cylinder management
system. This system allows two cylinders on each cylinder
bank to be shut off in certain circumstances, for example,
under low engine load. When these cylinders are shut off,
the other cylinders can work more effectively with reduced
throttle loss. This saves fuel and reduces exhaust
emissions.
The cylinders are shut off by keeping the corresponding
inlet and exhaust valves closed, and by eliminating the fuel
supply and ignition for these cylinders.
The inlet and exhaust valves are shut off via the Audi
valvelift system. To make this happen, the system’s actuators are activated in the same sequence as the firing order,
which sets the moveable cam elements for cylinder 2, 3, 5
and 8 to zero stroke.
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Firing order with all cylinders activated: 1-3-7-2-6-5-4-8
Firing order with half of cylinders activated: 1-7-6-4
For the vehicle occupants, it will be nearly imperceptible
that only half of the cylinders are activated, as the active
engine mountings eliminate nearly all potential vibrations.
The function of the active engine mountings is described in
SSP 920223 and SSP 990293
Cylinder 1
5/6
1/2
3/4
7/8
Cylinder 2
676_032
Legend
1.
2.
3.
4.
5.
6.
7.
8.
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Cylinder 2 Exhaust Cam Actuator 1 F454
Cylinder 2 Intake Cam Actuator 1 F452
Cylinder 3 Exhaust Cam Actuator 1 F458
Cylinder 3 Intake Cam Actuator 1 F456
Cylinder 5 Exhaust Cam Actuator 1 F466
Cylinder 5 Intake Cam Actuator 1 F464
Cylinder 8 Exhaust Cam Actuator 1 F478
Cylinder 8 Intake Cam Actuator 1 F476
Cylinder on Demand strategy
Criteria for starting/ending CoD operation
Engine coolant temperature
95°F - 185°F (35°C - 85°C)
Engine torque
Between 62.69 - 162.26 lb ft (85 - 220 Nm) depending on the engine speed
Gear
D
Inactive in gears
1…3
Battery voltage
Greater than 9,6 V
Catalytic converter heating
Inactive
Engine flaps
Inactive
Prevented during OBD diagnosis
› Oxygen sensor check
› Catalytic converter check
› Fuel tank breather check
EVAP system, high load greater than 12
Inactive
Maximum time in CoD cycle
300 s
Exhaust gas is captured and sealed in when the cylinders are shut off.
How the CoD system works
This section describes the three phases in which the sliding cams move from zero to full lift.
Phase 1
When the cam actuator is activated by the engine control
module, the actuator pin is inserted into the Y-shaped
slotted gate. The ball locks the cam element in place
through spring force. The intake and exhaust valves are
closed.
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Phase 2
When the camshaft rotates further, the shape of the
slotted gate causes the actuator pin to press the cam
element out of the retainer.
676_034
Phase 3
Once it has changed positions, the cam element is locked in
the second position by the ball through spring force. The
retraction slot pushes the actuator pin back in. This triggers
the retraction signal in the actuator. The intake and exhaust
valves are still closed; they are just about to be opened by
the contour of the full lift cam.
676_035
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Camshaft adjusters
To optimize power output and torque as well as reducing
emission levels and increasing fuel economy, camshaft
adjusters are installed on all camshafts. The system also
uses an internal exhaust gas recirculation strategy.
The hydraulic camshaft adjusters are in constant operation
and have an adjustment range of 50° (crank angle).
Diamond-coated friction washer,
must not be reused
Camshaft adjuster valve
(solenoid valve, bolted into chain case cover)
Intake camshaft Cylinder bank 2
Timing valve
(also secures camshaft adjuster to camshaft)
Reference
For more information about the camshaft adjuster valve and the control valve, please refer to eSelf-Study
Program 920173, The Audi 3.0L V6 TFSI EA839 Engine.
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Intake camshaft adjusters
When the engine is switched off, locking pins use spring
force to lock the intake camshaft adjusters in the “retard”
position.
Adjustment range 25° cam angle
Chain sprocket (rotor)
Stator
Locking pin
Direction of camshaft rotation
676_036
Exhaust camshaft adjusters
When the engine is switched off, spring force on the
locking pins locks the exhaust camshaft adjusters in the
“advanced” position. A return spring is necessary to achieve
the “advanced” locking position when switching off the
engine.
Chain sprocket (rotor)
Return spring
Locking pin
Stator
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676_144
Camshaft drive configuration
The camshaft drive system of the new V8 engine is located
on the transmission side of the engine. A gear on the crankshaft drives the intermediate gear which in turn drives the
simplex chains for the camshafts.
The intermediate gear is configured as a tensioning gear. It
is responsible for preventing noise.
Camshaft Position Sensor 4
G301
Camshaft Position Sensor 3
G300
Tensioning rail
Contact surface
Camshaft Position Sensor 2
G163
Contact surface
Exhaust Camshaft Adjustment
Valve 1 N318
Camshaft Adjustment Valve 2
N208
Exhaust Camshaft Adjustment Valve 2
N319
Camshaft Position
Sensor G40
Tensioning rail
Camshaft Adjustment Valve 1
N205
Guide rail
676_039
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Basic positions for crankshaft/camshaft timing
The engine is in its basic position when cylinder 1 is at TDC position and the crankshaft can be locked in place. The markings
on the camshaft adjusters must be opposite the corresponding projections on the camshaft housing. The camshaft adjusters
must be positioned precisely, as the drive chain sprockets are tri-oval shaped. These tri-oval chain sprockets make it possible
to minimize the dynamic forces from the valve gear and allow the engine to run more smoothly.
Marks for basic setting
676_040
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Locking the crankshaft
The crankshaft can be locked in two ways, as described below.
With the engine installed in the vehicle using lock in pin T10492
676_041
Locking pin T10492
With the engine removed using lock in pin T40069
Engine bracket
Locking pin
T40069
676_042
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Water pump drive shaft
The water pump drive shaft is mounted in sleeve bearings and is driven by a tensioning gear via the crankshaft.
676_043
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Tensioning gear
The tensioning gear must be pre-tensioned during installation using Locking Pin T40362.
Coolant pump drive shaft
Tensioning gear
Coolant pump drive gear
676_015
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Crankcase ventilation system
The crankcase is vented above the cylinder head covers. An oil separator module is bolted onto each cylinder head cover for
this purpose. The filtered blow-by gases are also channeled separately for each cylinder bank. The inlet points are located
upstream of the intake side of the turbocharger turbines (discharge at full load) as well as in the intake manifold of the
cylinder heads (discharge at partial load).
Intake is regulated by non-return valves which open or close independently depending on the pressure level in the air
supply. A non-return valve is installed in the breather line from the oil separator to the connection in front of the turbocharger turbines. The second non-return valve is installed in the corresponding oil separator module.
Oil seperator,
bank 2
Non-return valve
Non-return valve
Oil seperator,
bank 1
Breather line,
full load
Breather line,
partial load
Breather line,
partial load
Breather line,
full load
676_046
The ECM regulates the crankcase ventilation system. The
system must be capable of discharging approximately 3.53
cu ft (100 L) of blow-by gases from the crankcase without
loosing oil in the process.
676_047
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Blow-by discharge at partial load
On both cylinder banks, the filtered blow-by gases flow from the oil separator into the corresponding intake manifold. At
low air temperatures and high flow speeds, the blow-by mass flow is heated in the intake manifold to prevent it from
freezing under extreme conditions.
A PTC heater element is installed at the connection between the breather line and the intake manifold. It is controlled by
the ECM via a PWM signal based on a calculated characteristic map.
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Positive Crankcase Ventilation Heating Element N79 cylinder bank 1 (right-side)
Crankcase Ventilation Thermal Resistor 2 cylinder bank 2 (left-side)
Heater element for
crankcase ventilation
N483
N79
676_048
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Oil separator
The blow-by gases flow out of the crankcase and into the cylinder head area via channels in the crankcase. From there, the
blow-by enters an inlet plenum chamber in the cylinder head cover; this is where the oil separator is installed. When the
engine is running, oil that has been separated collects in the collection chamber of the oil separator.
Pressure regulating valve .23 psi
(85 mbar)
Connection for
intake manifold
Connection for
turbocharger
Non-return valve
Opens in
partial-load
operation
Oil separator
(impactor)
Non-return valve
Opens in full-load
operation
Blow-by inlet
Oil return channel
676_049
When the engine is not running or when a defined level in the oil separator is exceeded, the gravity valve opens and the oil
drains into the crankcase. The gravity valve also prevents oil from the sump from entering the oil separator in the event of
large fluctuations in pressure, for example due to sudden load change.
Oil return valve
(gravity valve)
676_050
Reference
For more information about the oil separator, please refer to eSelf-Study Program 920173, The Audi 3.0L V6
TFSI EA839 Engine.
38
Oil return
The separated oil in the oil separator collects in the cylinder head cover tray (located below the oil separator). It is
directed through a drilled channel down to the inlet side and then enters the valve chamber of the cylinder head via the
oil discharge valve.
Oil discharge valve
676_051
39
Engine breather
passages (inside)
Oil return channels (outside)
cylinder heads over crankcase
in sump
676_052
The oil flows into the sump via separate return channels. The inlet point is located below the oil surface level.
Oil return channels (outside)
cylinder heads over crankcase in sump
676_123
40
Positive Crankcase Ventilation (PCV)
Positive crankcase ventilation (PCV) takes place when
charge pressure is present. The air flow which is channeled
into the crankcase in this process is limited by defining the
cross-section of the pipe in the crankcase connection. In
certain operating modes, for example, to avoid blow-by
gases when mixture adaption is active, Crankcase Ventilation Valve N546 is actuated, which regulates the flow of
fresh air.
Two non-return valves are installed for security. They close
when the difference in pressure between the air system and
the crankcase becomes too great; otherwise the vacuum
pressure inside the crankcase could become too high. The
non-return valves are located in N546 and in the connection on the crankcase.
The fresh air intake point for the crankcase is located in
front of the throttle valve for cylinder bank 2. Air is drawn
into the crankcase at a connection just above the upper
sump on the left side of the engine.
Crankcase Ventilation Valve
N546
Fresh air intake
Fresh air extraction before
throttle valve
676_053
Crankcase
connection
Crankcase Ventilation
Valve N546
676_125
Crankcase connection
with non-return valve
and throttle function
676_126
41
Fuel tank ventilation
Fuel tank ventilation is controlled by Engine Control Module
J623. It is done by regulating the vapor flow from the
charcoal canister via EVAP Canister Purge Regulator Valve 1
N80 and EVAP Canister Purge Regulator Valve 2 N115.
When there is a vacuum in the intake manifold, the
activated charcoal filter is vented via the non-return valves
in the intake manifold. When there is charge pressure,
venting takes place on the intake side in front of the
turbocharger.
676_054
Tank Ventilation Pressure
Sensor 1
G952
From activated charcoal filter
EVAP Canister Purge Regulator
Valve 1
N80
EVAP Canister Purge
Regulator Valve 2
N115
Connection to intake manifold for
cylinder bank 1 with non-return
valve at partial load
Discharge to intake side of turbocharger at full load with assistance from suction-jet pumps
Tank Ventilation Pressure
Sensor 2
G951
Connection to intake
manifold for cylinder
bank 2 with non-return
valve at partial load
676_127
Tank Ventilation Pressure Sensors 1 and 2 are mounted
upstream of the EVAP Purge Regulator Valves. They are
used to check whether sufficient vacuum is present in the
fuel tank ventilation lines.
42
If a ventilation line is disconnected or leaky, a pressure drop
would not be measurable and the MIL would be switched on.
Suction-jet pumps for fuel tank breather system
During times when no vacuum is present in the intake
manifold, the fuel tank ventilation system discharges into
the turbocharger compressor housings. This is assisted by
suction-jets operating on the Venturi principle. The suction-jets utilize the pressure gradient between the pressure
and the intake sides of the compressor. The accelerated air
flow produces a vacuum which is used to ventilate the
charcoal canister.
676_056
Each suction-jet pump is connected to the intake side
(vacuum) and the pressure side of the turbocharger. Once
there is a sufficient difference in pressure between the
intake side and the pressure side, for example, at full load,
a “Venturi effect” is created. This extracts the fuel vapors
from the activated charcoal filter and directs them into the
intake side of the turbocharger.
Intake side
Turbocharger
Pressure differential
Venturi nozzle
Non-return valve
from activated
charcoal filter
Pressure side
Turbocharger
676_055
43
Vacuum system
Vacuum pressure is created by a single-vane pump driven by the inlet camshaft for cylinder bank 2.
The vacuum pump must supply the following components with vacuum pressure:
›
›
›
The mechanical coolant pump: to ensure standing coolant in the cylinder block when the engine is warming up.
The vacuum units of the turbocharger: to close the bypass flaps thus regulating the charge pressure.
The brake servo.
676_057
Charge Air Pressure Actuators V465 and V546 are electro-pneumatic exhaust gas recirculation valves. They are able to
initiate a calculated vacuum pressure (characteristic curve) according to the actuation (PWM) by the ECM. This determines
the degree to which the bypass flaps are open; they are open when not actuated.
Mechanical Coolant Pump Switch Valve N649 is an electric changeover valve. It can only be switched to “on” and “off”.
44
Connection for vacuum unit/
turbocharger
Pressure equalization hose to
prevent turbocharger pumping
Direction of flow
Non-return valve
Connection for
mechanical coolant
Charge Air Pressure
pump
Actuator V465
Connection for
brake servo
Mechanical
Coolant Pump
Switch Valve
N649
Connection for
vacuum reservoir
Shaft driven
engine coolant
pump
Outlet (vacuum
pressure input)
Oil Pressure Sensor
G10
Vacuum pump
Charge Air Pressure
Actuator 2
V546
Open when actuated;
otherwise closed
Always open
Open when not
actuated; closed when
actuated
180 cm3 single-vane
vacuum-pump with axial
elastomer seal
A sinterred plastic air filter is
installed because the breather
connection is within reach of
water spray (cannot be replaced
separately)
676_058
Pressure equalization between the vacuum units of the bypass flaps
If there are differences between the characteristic curves of the two charge pressure positioners, this could cause the
vacuum units to be actuated differently and create different pressure levels in the turbochargers, leading to undesired
noises (turbocharger pumping). A connecting pipe equalizes the pressure between the vacuum connections of the vacuum
units of both turbochargers.
45
Oil supply
The key objectives for the oil circuit development are to keep pressure losses to a minimum and ensure optimal flow.
Key technical features of the oil circuit are:
›
›
›
Fully variable map-controlled vane cell oil pump.
Piston cooling jets which inject directly into the piston crown cooling ducts.
Thermostat controlled engine oil cooler.
Oil circuit overview
676_059
Key:
A
B
C
D
Cylinder head 1
Cylinder block
Cylinder head 2
Cylinder head gallery
1
2
3
4
5
6
7
8
9
10
11
12
13
Oil pan
Oil Level Thermal Sensor G266
Oil intake with strainer
Oil pump
Oil-coolant heat exchanger (engine oil cooler)
Oil filter
Turbocharger
Bypass valve
Turbocharger non-return valve
Connecting rod
Pressure relief valve (cold start valve)
Oil Pressure Regulation Valve N428
Oil Pressure Sensor G10
46
14
15
16
17
18
19
20
21
22
23
24
25
26
Intermediate shaft bearing
Oil gallery for piston cooling jets
Oil Pressure Switch F22
Oil Temperature Sensor G8
Piston Cooling Nozzle Control Valve N522
Chain tensioner
Camshaft adjuster
Camshaft control valves
Camshaft bearings
Vacuum pump
High-pressure fuel pump
Hydraulic valve clearance compensation element
Oil drain valve
Overview of engine components
Oil heat exchanger
Oil filter module
Oil supply gallery for
components in the
cylinder head
Main oil gallery for crankshaft
bearing lubrication
Supply gallery to oil/coolant
heat exchanger
Control gallery to oil pump
Oil pump
676_060
47
Oil pump
Drive
The vane cell oil pump is driven by the crankshaft via a
chain drive on the front side of the engine. A 7mm chain
and leaf-spring chain tensioner (no hydraulic damping) is
used. A guide rail is installed on the driving side of the
pump due to the distance between the shafts for the chain
sprockets.
Oil Pressure
Regulation Valve
N428
Coolant pump drive
Leaf spring
Chain tensioner
Oil pump
Crankshaft chain sprocket,
31 teeth
Chain sprocket, 32 teeth
Chain sprocket shield to reduce
splash loss
Guide rail
Suction pipe with integrated oil
strainer (perforated plate) to
ensure oil supply during dynamic
driving
48
676_061
Oil pump
The fully variable vane pump has a very compact construction. It is bolted onto the crankcase. A metal gasket is necessary to
seal the individual oil passages from one another at the point where the components mate.
Return shut-off valve
Pressure relief valve
Rotary slide valve
Impeller
676_062
676_065
Oil pump: range of operation
Oil temperature in main gallery:
86 °F (30 °C)
Oil temperature in main gallery:
212 °F (100 °C)
676_063
Note
For new vehicles, two-stage oil pressure regulation is only activated after the first 620 mi (1000 km). This compensates for the higher friction when breaking in new parts and is the best way of removing particles of residue
worn off during the break-in process. After installing new components such as the engine/short block, cylinder
head, camshaft housing or turbocharger, activate the “engine run-in” program in the Guided Fault Finding (GFF).
This will ensure that only the high pressure stage is allowed for the next 620 mi (1000 km).
Reference
For further information regarding fully variable oil regulation, please refer to eSelf-Study Program 920173,
The Audi 3.0L V6 TFSI EA839 Engine.
49
Piston cooling
It is not necessary to cool the pistons with oil spray during
every phase of engine operation. When no cooling is
required, Piston Cooling Nozzle Control Valve N522 is
switched to ground by Engine Control Module J623. This
closes off the channel from the main oil gallery to the oil
gallery for the piston cooling jets.
When the oil gallery is closed, the oil pressure dissipates
via the piston cooling jets. Feedback to the ECM is provided
by the signal from Oil Pressure Switch F22. F22 is located
in the oil gallery and opens at pressures between 4.35 8.70 psi (0.3 - 0.6 bar).
Piston cooling jets
676_066
Piston cooling jets: range of operation
Piston cooling is activated based on a characteristic map that considers the variables of engine rpm, engine torque and oil
temperature. For this purpose, Oil Temperature Sensor G8 provides the engine oil temperature value of the main oil gallery.
Piston cooling is only activated at oil temperatures above 50 °F (10 °C).
676_067
50
Sensors and actuators
Oil heat exchanger
Oil Pressure Switch
F22
Oil filter module
Plastic oil filter module
with pressure relief valve in
cover assembly. Connection of
turbocharger oil supply with
integrated non-return valve.
Fully synthetic filter paper
Piston Cooling Nozzle
Control Valve
N522
Oil Temperature Sensor
G8
Oil Pressure Sensor
G10
Oil Level Thermal Sensor
G266
Oil Pressure
Regulation Valve
N428
676_068
Note
Oil Temperature Sensor G8, Oil Pressure Switch F22 and Piston Cooling Nozzle Control Valve N522 are located
under a heat shield.
Oil Temperature Sensor G8
G8 is also located in the inner V of the engine. This NTC
thermistor measures the temperature of the engine oil in
the main oil gallery. The ECM uses the signal primarily as
the input variable for calculating the oil pressure regulation.
In addition, the oil temperature in the main oil gallery
determines whether the piston cooling jets are activated.
For example, at oil temperatures over 248 °F (120 °C), the
piston cooling jets are activated even at low engine speeds.
676_154
51
Oil Level Thermal Sensor G266
The signal from G266 is evaluated by the ECM, which uses
the temperature and oil level values to compute the oil
change interval. The information regarding oil level and oil
temperature is transmitted to the ECM via a PWM signal.
The sensor has a 12 Volt power supply.
676_069
Piston Cooling Nozzle Control Valve N522
This solenoid valve operates on 12 Volt power. To activate
the solenoid valve and close the oil passage for the piston
cooling jets, the ECM switches it to ground. This means that
the valve would be open in the event that it should fail
(failsafe design).
676_070
52
Oil filter and oil-coolant heat exchanger
When the oil exits the oil-coolant heat exchanger, it flows
through a passage in the cylinder block and into the oil
filter module. Once it has been filtered, the oil flows into
the main oil gallery of the engine; from there, it reaches
the appropriate components via corresponding passages.
The engine oil circulated by the oil pump flows first
through the oil heat exchanger, which is installed in the
inner V of the engine and connected to the coolant circuit
on the coolant side.
676_071
The oil-coolant heat exchanger is designed to provide a
high degree of heat transfer. It comprises 19 stacked plates
with plates for turbulent flow (10 oil/9 water), which
provides a high degree of heat transfer. The coolant
circulates via counterflow with a flow rate of up to 63.40 qt
(60l) per minute.
Coolant
outlet
Coolant
inlet
Engine oil
inlet
Engine oil
outlet
Cross-flow of engine oil and coolant through exchanger
676_073
676_072
53
Oil filter module
The oil filter module is made of plastic and is installed in
front of the oil-coolant heat exchanger in the inner V of the
engine. This makes it very easy to replace the oil filter. A
stainless steel heat shield protects the oil filter module by
reflecting the heat that radiates from the turbocharger on
cylinder bank 2.
A bypass valve is installed in the housing cover which
directs the oil past the oil filter should it become clogged.
Two additional valves are installed in the oil filter housing.
The non-return valve prevents oil from flowing from the
turbochargers back into the sump. The oil drain valve opens
when the oil filter cover is unscrewed so that the oil drains
into the sump when the oil filter is exchanged.
Oil filter module
Cover seal
Bypass valve
Oil filter
Oil filter housing
Oil drain valve
Non-return valve
Heat shield
Seal
676_074
54
Oil supply in the cylinder head cover
The main oil gallery in the cylinder block supplies the oil
pressure to the cylinder head cover.
From the main oil gallery, oil is supplied to the camshaft
bearings, the hydraulic compensation elements, the
high-pressure fuel pump and (on cylinder bank 2) the
vacuum pump via branch ports. Oil is supplied to the large
camshaft bearings and the camshaft adjusters via the main
oil gallery of the cylinder head covers.
Main oil gallery, cylinder head
cover
Vacuum pump
High-pressure fuel pump
Hydraulic
compensation
elements
Pressure oil from main oil
gallery
Camshaft adjuster
676_075
55
Drive for ancillaries
The alternator and air conditioner compressor are each
driven by a separate drive belt. Both belt drives are driven
by the vibration damper of the crankshaft.
The belt drives are tensioned by automatic tensioning
devices and are maintenance-free.
Vibration damper
Tensioning roller
(top)
Tensioner for poly
V-belt
Starter-alternator
Air conditioner
compressor
676_076
Tensioning roller
(bottom)
Poly V-belt tensioner for starter-alternator
(belt tensioner/damper)
Idler roller
Poly V-belt tensioner for air conditioner compressor
(belt tensioner/damper)
676_077
56
Vibration damper
676_079
57
Cooling system
System overview
The new V8 engine has a thermal management system
which activates various partial cooling circuits as required
to help the engine, vehicle heating and transmission warm
up quickly.
In addition to providing greater convenience, the main
objective is to reduce fuel consumption and exhaust emissions.
676_080
58
Key:
1. Expansion tank
14. Cylinder head (right-side)
2. Heat exchanger for heater (front)
15. Cylinder block (right-side)
3. Heat exchanger for heater (rear)
16. Cylinder block (left-side)
4. Restrictor
17. Cylinder head (left-side)
5. High Temperature Circuit Coolant Pump V467
18. Engine Temperature Sensor G407
6. ATF cooler
7. Turbocharger, bank 1 (right-side)
19. Coolant pump (mechanical) With cover (standing coolant),
actuated by Mechanical Coolant Pump Switch Valve N469
8. Turbocharger, bank 2 (left-side)
20. Map Controlled Engine Cooling Thermostat F265
9. Engine oil cooler
21. Non-return valve
10. Transmission Fluid Cooling Valve N509
(actuated by Transmission Control Module J217)
22. Radiator
11. Transmission Coolant Valve N488
(actuated by ECM J623)
23. Engine Coolant Temperature Sensor on Radiator
Outlet G83
24. Restrictor
12. After-Run Coolant Pump V51
25. Coolant Recirculation Pump V50
13. Starter-alternator
26. Non-return valve
Cooled coolant
Warm coolant
Thermal management
The thermal management system is responsible for
coordinating the optimal process of warming up the
engine, transmission and pas­senger compartment.
Reducing vehicle emissions is a primary concern in this
process.
During the engine warm-up phase, the engine’s mechanical
coolant pump and Coolant Recirculation Pump V50,
After-Run Coolant Pump V51 and High Temperature Circuit
Coolant Pump V467 are switched off. Transmission Fluid
Cooling Valve N509 and Transmission Coolant Valve N488
are closed. All the components listed are actuated as
needed (as calculated by the characteristic map) so that
the required coolant flow is achieved.
To provide a calculation, the characteristic map in the ECM
requires numerous input parameters:
›
Engine coolant temperature
›
Ambient air temperature
›
Engine speed, engine torque, engine power output
›
Engine oil temperature
›
Road speed
›
Heating requirements
›
Driving mode
›
Radiator outlet temperature
›
Transmission oil temperature
The following components can be activated in response:
›
Mechanical Coolant Pump Switch Valve N649
›
Map Controlled Engine Cooling Thermostat F265
›
Coolant Recirculation Pump V50, After-Run Coolant Pump V51
and High Temperature Circuit Coolant Pump V467
›
Transmission Fluid Cooling Valve N509 and Transmission
Coolant Valve N488
59
Coolant circuit in cylinder block
Connecting pipe
Distribution pipe (hot) for
ancillaries, turbocharges,
oil-coolant heat changer
Supply flow for oil-coolant heat exchanger
Return flow for
oil cooler
Connecting pipe for
coolant (cold)
Coolant return (hot)
from ancillaries directly
to coolant pump
Coolant return (hot) to
radiator via thermostat
and coolant pump
Engine water jacket with
web cooling channels and
restrictor pins
Coolant supply gallery
(cold) from radiator via
coolant pump
676_081
60
Restrictor pins
It is very important to provide cooling to the cylinder webs
of the engine. Because they have a narrow cross-section, the
coolant does not flow through them as easily. The coolant
naturally always follows the path of least resistance.
It is not possible to do this with the casting technique used
to manufacture the cylinder block, so restrictor pins are
installed at the appropriate positions. Two restrictor pins
are installed in each cylinder bank.
To ensure that sufficient coolant can flow through the
cylinder webs, constrictions must be created at other areas
of the engine water jacket.
Restrictor pin
676_091
Engine water jacket
Restrictor pin
Cylinder web cooling
676_028
Note
When making repairs in this area, it is important to ensure that the restrictor pins are installed. Without them,
there would be no cylinder web cooling. This would cause the cylinder web areas to overheat, and certain
components would become distorted. If a cylinder head were to warp causing a head gasket leak, coolant could
leak into the combustion chamber.
61
Cooling concept for the cylinder head
The cylinder heads have the greatest cooling requirement compared to the other components in the cooling system. The
flow to cylinder block and cylinder head is distributed at a ratio of 20:80, with up to 39.62 gal (159.0 L). of coolant per
minute per cylinder head.
Breather pipe - coolant to
coolant expansion tank
in vehicle
Outlet side - coolant
outflow to distribution
gallery for crankcase
(hot)
Coolant intake passages
from coolant supply
gallery for crankcase
(cold)
676_083
Flow around valve seat
inserts (outlet side)
Flow around valve seat
inserts (inlet side)
676_084
62
Components on the engine
View of front
Radiator return
(cold)
Mechanical Coolant Pump
Switch Valve N649
Coolant distribution
module
Engine Temperature Sensor
G407
Map Controlled Engine Cooling
Thermostat
F265
Radiator supply (hot)
676_085
View of transmission side
Coolant supply line turbocharger
Coolant return line turbocharger
Coolant line for
transverse pipe
Coolant line for
transmission
cooling
Heating supply line
Heating return line
After-Run Coolant Pump
V51
676_086
After-Run Coolant Pump V51
V51 is activated when greater cooling is required for the turbochargers at high engine loads. In addition, the pump operates
for a defined period after the engine is switched off. This helps prevent heat-soak in the turbochargers. The electric radiator
fan runs as well. To activate V51, the thermal management system performs calculations using the engine speed, engine
torque, ambient temperature and coolant temperature.
›
›
The after-run time lasts between 10 and 45 minutes (depending on the operating status of the engine).
Delivery rate ~ 132.0 gal (500 L) per hour.
63
Coolant distribution module
The primary component of the thermal management
system is installed on the front of the engine. In the
coolant distributor housing, the flow of coolant is directed
to the radiator, ancillaries and engine. The vacuum-controlled coolant pump and the map-controlled engine
cooling system thermostat are located here as well. The
coolant pump is driven by the intermediate shaft via a
sprocket.
When the coolant pump opens the passage for the coolant,
it flows through the entire engine, that is, through the
cylinder heads as well. In other words, “split cooling” is not
used on this engine. The flow to the cylinder block and
cylinder head is distributed at a ratio of 20:80. For this
reason, only one temperature sensor (G407) is installed for
the entire engine; it is installed at an optimal location on
the cylinder head of bank 2.
Map Controlled Engine
Cooling Thermostat
F265
Coolant from radiator
(cold)
Coolant to radiator
(hot)
Oil Pressure Sensor
G10
To belt-driven
starter-alternator
676_087
Map Controlled Engine
Cooling Thermostat
F265
Coolant return (hot)
from ancillaries directly
to coolant pump
Coolant return (hot)
to radiator via thermostat
and coolant pump
Coolant supply (cold)
from radiator
Coolant pump/vacuum
regulating assembly
Coolant supply (cold)
from radiator
676_088
64
Map Controlled Engine Cooling Thermostat F265
The coolant temperature calculated in the characteristic
map can be regulated between 201.2 °F - 222.8 °F
(94 °C - 106 °C) as required. If the temperature is above
201.2 °F (94 °C), the ECM actuates the map-controlled
engine cooling system thermostat via a PWM signal.
To protect the engine, the coolant temperature is lowered
(F265 is not actuated) in the following situations:
›
›
›
›
›
Driving mode Sport.
Vehicle speed greater than 124.2 mph (200 km/h).
Engine torque 438.8 lb ft (595 Nm).
Engine temperature greater than 246.2 °F (110 °C).
System DTCs.
676_089
Map Controlled Engine
Cooling Thermostat
F265
Coolant distribution
module
Gasket
676_022
Coolant pump/vacuum
regulating assembly
Reference
For more information about the map-controlled engine cooling thermostat please refer to eSelf-Study Program
920173, The Audi 3.0L V6 TFSI EA839 Engine.
65
Regulating strategy of the mechanical coolant pump
The on-demand mechanical coolant pump is activated
when the following conditions are met:
›
›
›
›
›
Coolant temperature between -14 °F - 176 °F (10 °C - 80 °C).
Ambient temperature greater than 50 °F (10 °C).
Engine torque greater than 368.7 lb ft (500 Nm) with all
cylinders activated.
Engine torque greater than 110.6 lb ft (150 Nm) with half of
cylinders activated, depending on the coolant temperature and
engine speed.
Time since engine start greater than 600 seconds (10 minutes).
If a signal is sent indicating the need to heat the passenger
compartment during the engine warm-up phase, the
impeller of the mechanical coolant pump is covered by the
sleeve and Coolant Recirculation Pump V50 is switched on.
In this way, pump V50 pumps coolant from the cylinder
head into the heat exchanger.
Conditions prohibiting activation:
›
›
Coolant temperature greater than 176 °F (80 °C).
Engine speed greater than 3250 rpm.
Mechanical Coolant
Pump Switch Valve
N649
Sleeve
Cover plate
Pump gear
Drive gear
Vacuum regulating unit
676_090
66
Transmission coolant circuit
High Temperature Circuit
Coolant Pump V467
3
2
1
Transmission Fluid
Cooling Valve
N509
ATF heat exchanger
ATF return line
ATF supply line
676_093
ATF return line
ATF supply line
N509
3
V467
ATF heat exchanger
1
N488
2
Supply flow
1. From radiator outlet
2. Warm coolant from engine
676_094
The transmission coolant circuit can operate in three
different system states:
Standing coolant
Return
3. To distribution pipe (hot), engine
N488
N509
V467
Transmission Coolant Valve
Transmission Fluid Cooling Valve
High Temperature Circuit Coolant Pump
›
›
›
N509 supplied with current (valve closed).
V488 not supplied with current (valve closed).
V467 not running.
ATF heating
›
›
›
N509 supplied with current (valve closed).
N488 supplied with current (valve open).
V467 running.
ATF cooling
›
›
›
N509 not supplied with current (valve open).
N488 not supplied with current (valve closed).
V467 running.
67
Transmission Fluid Cooling Valve N509 and Transmission Coolant Valve N488
These map-controlled solenoid valves control the inflow of
warm coolant from the engine to the ATF cooler/cold
coolant from the main radiator to the ATF cooler. Both
valves are supplied with 12 Volt current. To activate them,
the corresponding control module switches them to
ground.
Valve N509 is activated by Transmission Control Module
J217, which closes it. Activation is initiated by the thermal
management system of the ECM. The valve is open when it
is not supplied with current.
N488 is activated by the Engine Control Module J623. The
valve is closed when it is not supplied with current.
High Temperature Circuit Coolant Pump V467
This pump is identical in form to pumps V50 and V51. It is
responsible for pumping the coolant through the
transmission coolant circuit.
676_095
Note
Valves N488 and N509 look similar and are easily mistaken for one another; however, the part numbers are different.
68
Air supply
Overview of air ducts
Different versions of the air supply system are used
depending on the vehicle type and engine power output.
The system shown here is for the 2020 Audi A8L. The air
pipe connected to the air cleaner distributes intake air to
both turbochargers.
Air pipe
Connection for crankcase breather
Charge Air Pressure
Actuator 2
V546
Manifold Absolute Pressure
Sensor 2
G429
Throttle Valve Control Module
GX3
Throttle Valve Control Module 2
GX4
676_096
69
Intake side
An inlet guide element is installed in the air pipe at the
point where the air pipe connects to the turbocharger. This
calms the flow of air before it enters the turbocharger. In
addition, the air flow is given a slight “swirl” in the direction of the fan blades, which improves the acoustics of the
air intake.
From air cleaner
Inlet guide element
Pressure side
676_097
The air compressed in the turbochargers is channeled to
the charge air coolers via pulsation dampers as an acoustic
measure against air noise. The connecting pipe joins both
outlets of the turbochargers with one another. This
dampens out-of-phase pressure oscillations and helps
prevent compressor surge.
From air cleaner
From charcoal canister
Pulsation
damper
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Connecting
pipe
676_142
Pulsation damper
Pulsation
damper
70
Intake manifolds
The intake manifolds are bolted to the cylinder heads. A
throttle valve module is installed upstream of each intake
manifold. EA825 engines do not require intake manifold
flaps.
Both intake manifolds have connections for the activated
charcoal canister and crankcase breather. Fuel vapors/
blow-by gases enter the intake manifold when there is
vacuum pressure inside it. The third connection is for the
brake servo (note: the connection on the intake manifold
for bank 1 is non-functional).
Manifold Absolute
Pressure Sensor
G71
Intake manifold,
bank 1
Manifold Absolute Pressure
Sensor 2
G429
Throttle Valve
Control Module
GX3
Intake manifold,
bank 2
Throttle Valve Control Module 2
GX4
676_113
The intake manifold pressure sensors measure the intake
manifold pressure and the temperature of the intake air.
The ECM uses the signals from the sensor downstream of
the throttle valves to measure the air mass (volumetric
efficiency measurement).
The signals from the sensors upstream of the throttle
valves are used by the ECM to calculate and set the desired
charge pressure. The signals are transmitted to the ECM by
SENT protocol.
Manifold Absolute Pressure
Sensor 2
G429
Connection for brake servo to
intake manifold, bank 1 (blind)
Charcoal canister connection
Crankcase Ventilation Thermal
Resistor 2
N483
Throttle Valve Control Module 2
GX4
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71
Throttle Valve Control Modules GX3 and GX4
A throttle valve module is installed upstream of each intake
manifold. Non-contact throttle valve position sensors (Hall
sensors) are used to determine the position of the throttle
valves. They operate on the principle of redundancy,
meaning that the feedback regarding the position of the
throttle valve is delivered by two sensors working independently of and opposed to one another.
A DC motor with a two-stage gear assembly acts as an
actuator for the throttle valve. This keeps the throttle valve
positioned between the two mechanical limit stops. The
position of the throttle valve is calculated based on the
position of the accelerator pedal and the required engine
torque.
DC motor power
supply
Electrical
connection
DC motor
Sensor unit
Throttle valve
Two stage gear
assembly
Note
There are no master list terms for the throttle valve position sensors.
72
676_115
Turbocharging
Twin scroll exhaust manifold
The exhaust manifolds have a twin scroll design. With this separation, two cylinders create one stream of exhaust which is
kept separate in its own channel inside the turbocharger until it reaches the turbine. Keeping the channels separate helps
prevent the individual cylinders from affecting one other adversely during gas exchange.
Background:
The firing order on each cylinder bank creates a 180° firing interval for some cylinders. The exhaust compression waves
(created when the valves open) from these cylinders would affect one another if they were able to interact via the exhaust
manifold. This, in turn, directly affects the gas exchange, because the volume of fresh air would be reduced. The twin scroll
design keeps the gases from those cylinders separate which correspond unfavorably with one another. This provides a
significant torque advantage in the low engine RPM range.
Exhaust manifolds located in the inner V of the engine.
Twin scroll exhaust manifold
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676_011
73
Twin scroll turbochargers
The gas flow paths are very short because the turbochargers are located centrally in the inner V of the engine. As a result,
turbocharger response is very direct. The turbines rotate in opposite directions: The turbine on bank 1 rotates counter-clockwise; the one on bank 2 rotates clockwise. This design makes the best use of the space available.
676_118
Oil return line
Coolant supply line
Vacuum unit for charge pressure
regulating valve
676_139
74
Twin scroll turbochargers continued
Twin scroll turbocharger
Turbine (intake side)
Turbine (exhaust side)
Charge pressure
regulating valve
Twin scroll exhaust manifold
676_140
75
Turbocharger mounting
The turbochargers are secured to the exhaust manifolds
with screw-type clips (V-band clamps). A gasket (made of
mica-based material) seals off the connection between the
two components.
The hot side of the turbocharger and the exhaust manifold
are surrounded by insulating covers. This protects the
adjacent components in the inner V and helps conserve a
larger percentage of the exhaust energy.
Screw-type clip (V-band clamp)
676_138
Insulating cover for
exhaust manifold
Screw-type clip (V-band clamp)
Seal
Locating pin for V-band
clamp (assembly aid)
Integral insulation (temperature can be lowered
by up to 752 °F (400 °C)
76
676_082
Turbocharger oil and coolant connections
The turbochargers are incorporated in the engine oil and
coolant circuits to ensure that the turbine shafts and
bearing are lubricated and cooled.
Coolant circulates through the turbochargers for a defined
period of time after a hot engine has been switched off.
This prevents heat soak and protects the components.
676_119
Coolant supply
Oil return line
Coolant supply line
Coolant return
Heat protection on silicone
hoses below the turbochargers
676_120
676_141
77
Heat shield in inner V of engine
The exhaust manifolds are located in the inner V of the
engine (HSI). The adjacent components require protection
to prevent them from becoming too hot. Additional heat
shields are installed for this purpose in the inner V along
with the heat shields on the exhaust manifolds and turbochargers. A heat shield is installed as additional protection
under the engine compartment cover. This cover should
always be in place when the engine is running. You can only
ensure that cool air reaches the inner V of the engine unless
all the components are properly installed.
All supply lines in the inner V are also made of heat-resistant materials (stainless steel, silicone) and in some cases
are installed with additional heat shields. Engine Cover
Temperature Sensor G765 monitors the temperature levels
in the inner V of the engine. If the NTC thermistor registers
temperatures that are too high, the ECM initiates cooling
measures.
Engine compartment cover
Heat shield
Heat shield for oil filter
module
Engine Cover
Temperature Sensor
G765
Side plate
Inner heat shield.
Protects the sensors and
piston cooling jet control
valve
676_121
78
Exhaust system
The exhaust system shown is designed for versions with PR
numbers EU6 AD/E/F (7CN), EU6 plus (7MM), ULEV125
(7MU) and EU4 (7GH).
Oxygen sensor control is done by a broad-band Oxygen
Sensor before the pre-catalytic converter and a two-state
sensor after it. Due to limited space, an additional catalytic
converter is located in the area of the underbody.
GX10
GX7
GX11
GX8
J883
J945
676_100
Key:
GX7 Oxygen Sensor 1 After Catalytic Converter
G130 Oxygen Sensor After Catalytic Converter
Z29 Heater for Oxygen Sensor 1 After Catalytic Converter
GX8 Oxygen Sensor 2 After Catalytic Converter
G131 Oxygen Sensor 2 After Catalytic Converter
Z30 Heater for Oxygen Sensor 2 After Catalytic Converter
GX10 Oxygen Sensor 1 Before Catalytic Converter
G39 Heated Oxygen Sensor
Z19 Oxygen Sensor Heater
GX11 Oxygen Sensor 2 Before Catalytic Converter
G108 Heated Oxygen Sensor 2
Z28 Oxygen Sensor 2 Heater
J883 Exhaust Door Control Unit
J945 Exhaust Door Control Unit 2
79
Fuel system
Fuel is supplied from the fuel tank to high pressure pumps
on the engine by an electric pump. The pressure varies from
43.51 to 79.77 psi (3 to 5 bar). The system does not have a
fuel return line. The amount of fuel required is calculated
by the ECM; the amount supplied is always just enough to
prevent bubbles from forming in the system.
Low Fuel Pressure Sensor G410 in the low-pressure pipe to
monitor the low pressure in the system. Due to the greater
fuel requirement for the V8 engine, each cylinder bank has
its own high-pressure fuel pump. Each cylinder bank has its
own high-pressure supply. The two systems are not connected to one another on the high-pressure side.
Overview of the high-pressure system
Low Fuel Pressure Sensor
G410
Fuel Metering Valve 2
N402
Fuel Metering
Valve N290
Fuel Pressure
Sensor G247
High-pressure
line
Cylinder 4 Fuel Injector
N33
Cylinder 8 Fuel Injector
N86
Cylinder 3 Fuel Injector
N32
Cylinder 7 Fuel Injector
N85
Cylinder 2 Fuel Injector
N31
Cylinder 6 Fuel Injector
N84
Cylinder 1 Fuel Injector
N30
Cylinder 5 Fuel Injector
N83
Fuel Pressure
Sensor 2
G624
High-pressure
rail
676_104
High pressure fuel pumps
The high-pressure fuel pumps are driven by roller tappets
and four-lobe cams positioned on the exhaust camshafts.
The maximum pressure generated is 3625.94 psi (250
bar). At approximately 4351.13 psi (300 bar), the pressure
limiting valve in the pump opens.
The pump is open when no current is applied (fail-safe).
This means that without electric actuation, the pump runs
at the same pressure as the supply from the pump in the
fuel tank.
High-pressure fuel pump
High-pressure
connection
Roller tappet
Four-lobe cams
Exhaust camshaft
676_102
80
High-pressure injector
The injector is positioned directly next to the spark plug.
This central position, together with adjustments to the
injector hole diameter and the spray pattern suited to the
conditions in the cylinder, helps provide the most homogeneous fuel distribution possible.
›
›
›
›
›
›
›
7-hole injector.
Injector hole diameter: 0.007 in (0.19 mm).
Needle lift: 0.0027 in (0.07 mm).
Up to 65 V actuation.
Injection period: 0.3 - 6 ms.
Up to 3 injections possible (depending on engine speed).
Injection pressure: approximately 1015.26 to 3625.94 psi
(70 to 250 bar).
High-pressure fuel pump
Exhaust camshaft
(four-lobe)
Spark plug (spark plug
aperture)
7-hole injector
(positioned centrally in
cylinder head)
Spray pattern of 7-hole
injector (in combustion
chamber)
676_106
Fuel supply rail
connection
Electrical
connection
Injector holes
Cross-section of injector holes
Teflon ring
676_103
676_128
676_122
81
Engine management
System overview
Sensors
Accelerator Pedal Module GX2
Accelerator Pedal Position Sensor G79
Accelerator Pedal Position Sensor 2 G185
Cruise Control Switch E45
Transmission Coolant Valve N488
Oil Pressure Switch F1
Oil Temperature Sensor G8
Tank Ventilation Pressure Sensor 1 G950
Tank Ventilation Pressure Sensor 2 G951
Oil Pressure Sensor G10
Oil Level Thermal Sensor G266
Fuel Pressure Sensor G247
Fuel Pressure Sensor 2 G624
Low Fuel Pressure Sensor G247
Low Fuel Pressure Sensor 2 G624
Engine Coolant Temperature Sensor on Radiator Outlet G83
Engine Cover Temperature Sensor G765
Crankcase Pressure Sensor G1068
Charge Air Pressure Sensor G31
Engine Temperature Sensor G407
Charge Air Pressure Sensor 2 G447
Engine Speed Sensor G28
Camshaft Position Sensors
G40, G163, G300 and G30
Knock Sensors
1-4 G61, G66, G198, G199
Fuel Tank Leak Detection Module GX36
Manifold Absolute Pressure Sensor 2 G429
Exhaust Gas Temperature Sensors G495
and G648
Brake Light Switch F
Brake Pedal Position Sensor G100
(integrated in Brake Light Switch F)
Assembly Mount Sensor 1 and 2 (G748 and G749)
Throttle Valve Control Module GX3
Throttle Valve Control Module J338
Throttle Valve Control Module 2 GX4
Throttle Valve Control Module 2 J544
Exhaust Gas Temperature Sensor 3 Bank 2 G497
Exhaust Gas Temperature Sensor 4 Bank 2 G649
82
Actuators
Starter Relay 1 J906
Starter Relay 2 J907
Comfort System Central
Control Module J393
(Convenience CAN)
Accelerator Pedal Module GXw2
Active Accelerator Pedal Motor V592
Transmission Mount Valve 1 N262
Transmission Mount Valve 2 N263
Transmission Coolant Valve N488
Data Bus On Board
Diagnostic Interface J533
Transmission Fluid Cooling Valve N509
High Temperature Circuit Coolant Pump V467
ABS Control Module
(FlexRay)
Piston Cooling Nozzle Control Valve N522
Assembly Mount Control
Module J931 (Extended
CAN)
Recirculation Valve, Bank 2 N626
Oil Pressure Regulation Valve N428
Fuel Pump Control
Module J538
Ignition Coils 1-4 with Power Output Stage: N70, N127,
N291, N292
Ignition Coils 5-8 with Power Output Stage: N323, N324,
N325, N326
Cylinders 1- 4 Fuel Injectors N30, N31, N32, N33
Cylinders 5-8 Fuel Injectors N83, N84, N85, N86
Fuel Metering Valve N290
Fuel Metering Valve 2 N402
Engine Control Module
J623 (FlexRay)
Mechanical Coolant Pump Switch Valve N649
After-Run Coolant Pump V51
Exhaust Door Control
Unit J883
Exhaust Door Control
Unit 2 J945
Starter-Generator C29
(sub-bus system)
Inlet cam actuator 1 for cylinders 2, 3, 5 and 8
F452, F456, F464, F476
Exhaust cam actuator 1 for cylinders 2, 3, 5 and 8
F454, F458, F466, F478
Crankcase Ventilation Valve N546
Map Controlled Engine Cooling Thermostat F265
VAP Canister Purge Regulator Valves 1 and 2 N80, N115
Camshaft control valves 1 and 2 N205, N208
Exhaust camshaft control valves 1 and 2 N318, N319
Charge Air Pressure Actuators 1 and 2 V465, V546
Radiator Fan Control Module J293
Radiator Fan V7
Radiator Fan Control Module J293
Radiator Fan 2 V177
Assembly Mount Actuators 1 and 2
N513, N514
Throttle Valve Control Module GX3
Throttle Valve Control Module J338
Throttle Valve Control Module 2 GX4
Throttle Valve Control Module 2 J544
676_107
Oxygen Sensor 1 Before Catalytic Converter GX10
Oxygen Sensor Heater Z19
Oxygen Sensor 1 Before Catalytic Converter GX11
Oxygen Sensor 2 Heater Z28
Oxygen Sensor 1 After Catalytic Converter GX7
Heater for Oxygen Sensor 1 After Catalytic Converter Z29
83
Oxygen Sensor 2 After Catalytic Converter GX8
Heater for Oxygen Sensor 2 After Catalytic Converter Z30
Engine Control Module
The engine management system of the EA825 series engines is controlled via Engine Control Module J623 using BOSCH
MG1 software. The ECM processes the incoming system information and controls the various functional groups. It is a node
in the vehicle’s data transfer network.
Data Bus On Board Diagnostic Interface
J533
Engine Control Module
J623
676_124
Starter Generator
C29
676_137
		FlexRay
		Sub-bus systems
Note
For further information about the engine management system of the EA825 series engines please refer to eSelf-Study
Program 920173, The Audi 3.0L V6 TFSI EA839 Engine
84
Inspection and maintenance
Service information and operations
Engine oil capacity (incl. filter) in liters
(change capacity)
4.3
Service interval
According to service interval display, between 15,000 km/ 1 year and 30,000 km /
2 years depending on driving style and conditions of use.
Engine oil specification
VW 504 00
Engine oil extraction permitted
No (draining only)
Air filter change interval
60,000 miles
Spark plug change interval
40,000 miles (60,000 km) / every 6 years
Fuel filter change interval
–
Timing assembly
Chain (lifetime)
85
Special tools and workshop equipment
Thrust piece T40019/4
Adapter T40320/4
676_108
Accessories for oil seal extractor T40019, for pressing off from
the crankshaft
Cleaning tool T90006
Installing oil seal on crankshaft (pulley end).
Guide plate VAS 5161/43
676_110
For cleaning the injector bores on V6 and
V8 TFSI engines
Adapter T90005
676_146
For removing and installing the valve stem
oil seals with the engine installed
Engine bracket V8 TFSI VAS 6095/1-17
676_111
The adapter is used in conjunction with
T10055 and is used for removing the injector
Engine bracket V8 TFSI VAS 6095/1-18
676_147
86
676_109
676_148
The adapter together with engine and gearbox support VAS
6095A, ASE 456 004 01 000 and universal support VAS 6095/1,
ASE 456 050 00 000 (depending on engine, support for 8-cylinder
TFSI engines).
The adapter together with engine and gearbox support VAS 6095A,
ASE 456 004 01 000 and universal support VAS 6095/1,
ASE 456 050 00 000 (depending on engine, support for 8-cylinder
TFSI engines).
Engine bracket V8 TFSI VAS 6095/1-17A
The new product has some technical modifications, but the previous product can still be adapted for use. The application and adaptation are described in ElsaPro.
Engine bracket V8 TFSI VAS 6095/1-18A
The new product has some technical modifications, but the previous product can still be adapted for use. The application and adaptation are described in ElsaPro.
Knowledge assessment
An On-Line Knowledge Assessment (exam) is Available for this eSelf-Study Program.
The Knowledge Assessment is required for Certification credit.
You can find this Knowledge Assessment at: www.accessaudi.com
From the accessaudi.com Homepage:
› Click on the “App Links”
› Click on the “Academy site CRC”
Click on the Course Catalog Search and select 920493 - “The Audi 4.0l V8 TFSI engine from the EA825 series”.
Please submit any questions or inquiries via the Academy CRC Online Support Form
which is located under the “Support” tab or the “Contact Us” tab of the Academy CRC.
Thank you for reading this eSelf-Study Program and taking the assessment.
87
920493
All rights reserved.
Technical specifications subject to
change without notice.
Audi of America, LLC
2200 Ferdinand Porsche Drive
Herndon, VA 20171