Service.
For internal use only
198
All rights reserved. Subject
to change.
AUDI AG
Dept.I/GS-5
D-85045 Ingolstadt
Fax +49.841/89-6367
740.2810.17.20
Technical status: 01/98
Printed in Germany
The 2.7-litre V6 Biturbo
Design and Function
Self-study Programme 198
The 2.7-litre V6 biturbo .......
Turbocharged engines are already something
of a tradition at AUDI. The task now facing
AUDI’s engineers was to develop a worthy
successor to the 5-cylinder turbocharged
engine.
One of the key development goals for the
turbocharged engine was to achieve a good
level of dynamic response, particularly at the
bottom end of the rev band.
The goal of AUDI’s engineers was to realise a
high “basic torque level“ and a torque
characteristic that rises in direct proportion to
engine speed to its peak.
The term “basic torque level“
describes the torque which is
immediately available when the
throttle is opened (e.g. at part
throttle or in overrun).
SSP 198/77
........ a further milestone in engine development by Audi!
2
Page
Contents
Engine .........................................................
Technical data, crankshaft, cylinder head,
camshaft timing, cooling circuit, engine
lubrication, overview of components, air ducting,
charging, exhaust system, pneumatically
controlled systems, charge pressure control, air
divert control in overrun, ACF system, crankcase
breather
Motronic ME 7.1..........................................
Subfunctions, system overview
Subsystems of the Motronic .....................
Torque-oriented engine management, torqueoriented functional structure, Electronic throttle,
exhaust gas temperature control
Sensors .......................................................
Additional sensors of the Motronic
4
31
33
49
Auxiliary signals/interfaces ...................... 57
Functional diagram..................................... 62
Self-diagnosis .............................................
Vehicle diagnosis, test and information system
VAS 5051, test box V.A.G 1598/31
Transmission ..............................................
Self-adjusting clutch, gearbox
This Self-study Programme provides you with information
regarding design and function.
The Self-study Programme is not a Workshop Manual!
Please refer to the Service Literature for all the relevant
maintenance and repair instructions.
64
66
New!
Important!/Note!
3
Engine
The 2.7-litre V6 biturbo
This engine will also be used in the Audi S4
and Audi A6.
The engine used in the A6 has a comfortoriented setup, which means that it has
different torque and power output.
This effect was principally achieved by
modifying the software configuration of the
engine control unit.
A tuning protective device prevents
the S4 engine control unit being
installed in the A6!
This prevents misuse, which can
result in damage to the drivetrain!
An auxiliary heater is not available
as an option for the S4 and the A6,
due to the constraints on space.
BITURBO
SSP 198/01
4
The technical data
•
Configuration:
V6 engine with 90° V-angle and twin
turbochargers
•
Engine code:
S4: AGB
A6: AJK
500
450
400
350
300
250
S4
200,0
180,0
160,0
140,0
120,0
100,0
•
Output:
S4: 195 kW at 5800 rpm
A6: 169 kW at 5800 rpm
•
Torque:
S4: 400 Nm at 1850 to 3600 rpm
A6: 310 Nm at 1700 to 4600 rpm
•
Maximum speed:
6800 rpm
•
Compression ratio:
9.3 : 1
•
Displacement:
2671 cm
•
Bore:
3
81 mm
•
Stroke:
86.4 mm
•
Weight:
approx. 200 kg
•
Engine management:
Motronic ME 7.1
•
Firing order:
1-4-3-6-2-5
•
Fuel type:
S4: 98/95/91 RON
A6: 95/91 RON
•
Compliant with emission standard:
EU III-D
200
Torque [Nm]
150
100
50
0
0 1000 2000 3000 4000 5000 6000 7000
SSP 198/02
500
450
400
350
300
250
200
Torque [Nm]
150
100
50
0
0 1000 2000 3000 4000 5000 6000 7000
SSP 198/46
80,0
60,0
40,0
20,0
0,0
Speed [rpm]
Figures obtained using 98 RON
unleaded premium fuel to
89/491/EEC.
A6
180,0
160,0
140,0
120,0
100,0
80,0
60,0
40,0
20,0
0,0
Speed [rpm]
Figures obtained using 95 RON
unleaded premium fuel to
89/491/EEC.
Output [kW]
Output [kW]
5
Engine
The crankshaft
The crankshaft is identical to that used in the
2.8-litre V6 engine.
The crankshaft bearing caps are attached to
the central crankcase by 4 bolts.
•
The 4-bolt connection reduces the load on
the bearing caps considerably.
The middle two crankshaft bearing caps are
also bolted to the side of the crankcase.
•
The lateral bolted connection helps to
improve acoustics.
The pistons are forged to enable them to
withstand the high loads to which they are
subjected.
Due to the high combustion pressures, a 2material bearing shell is installed on the
connecting rod side. The bearing cap has a 3material bearing shell.
Advantage:
The bearing shell has a high load-bearing
capacity
SSP 198/11
Lateral bolted connection
6
2-material
bearing shell
4-bolt connection
3-material
bearing shell
Cylinder head
The cylinder heads are largely identical to
those used in the V6 naturally aspirated
engine. Common parts are used for both banks
of cylinders.
The mounting position of the right-hand
cylinder head is rotated through an angle of
180° in relation to the left-hand cylinder head.
The timing of the inlet camshafts is enginedependent.
To improve heat dissipation, the exhaust
valves are sodium-filled.
Tumble duct
In combination with five-valveper-cylinder technology, the inlet
duct is shaped as a so-called
“tumble duct“.
The shape of the inlet duct causes the drawnin air to tumble.
Advantages:
•
A good degree of swirl and high ignitability
fuel-air mixture are achieved
•
The tumble effect allows more efficient
combustion
For a turbocharged engine, the compression
ratio of 9.3 : 1 is high.
Advantage:
•
High ”basic torque level“ and fuel
economy
Tumble effect
Tumble duct
SSP 198/78
7
Engine
The variable valve timing
The camshaft timing has been modified
compared to the 2.8-litre V6 engine to meet the
demands of turbocharging technology.
Variable valve timing with an adjustment angle
of 22° is used here for the first time in
turbocharged engines
Advantage:
•
A torque increase of approx. 10% is
achieved at the bottom and top ends of the
engine speed range.
•
Better emission levels and fuel
consumption figures.
The variable valve timing is activated by the
Motronic by means of camshaft adjustment
valves N205 and N208.
Diagram of variable valve timing
(shown using the 265 bhp engine as an
example)
.
The design and function of the
variable valve timing are already
described in Self-study Programmes
182 and 192.
Activation of the variable valve timing is
dependent on engine load and speed.
In the self-diagnosis, you can find out whether
the variable valve timing is active or not by
reading out the relevant measured value block
(refer to Workshop Manual).
Variable valve timing active
= advance position
8
Full throttle
SSP 198/45
Engine load in %
0
0 1000 2000 3000 4000 5000 6000 7000
Engine speed
Cooling circuit
Both exhaust gas turbochargers are watercooled and integrated in the cooling circuit.
When the coolant thermostat is closed, the
coolant flows back to the coolant pump along
the short-circuit line as well as the heat
exchanger.
When the coolant thermostat is open, the
coolant flows back to the coolant thermostat
through the radiator (primary flow) or through
the oil cooler and expansion tank (secondary
flow).
Coolant temperature
senders G2 and G62
Continued coolant function pump
Located in the cooling circuit is a electrical
coolant pump.
This pump is required as a means of
protection against overheating of the coolant
under high thermal load, e.g. when the hot
engine is turned off.
Heat exchanger
Thermoswitch for F95
Short-circuit
line
Coolant
Expansion
tank
SSP 198/03
Radiator fan thermoswitch F18/F54
Coolant pump
Oil cooler
Radiator
9
Engine
Electrical coolant circulation pump V51
Electrical coolant circulation pump V51 is
located in the engine’s V angle.
If the coolant temperature is too high,
thermoswitch for coolant circulation run-on
F95 activates the additional coolant function.
The high temperatures which occur at the
exhaust gas turbocharger produce vapour
bubbles which prevent coolant being drawn in
by pump V51.
When pump V51 starts up, the coolant flows
through the exhaust gas turbocharger and the
cylinder heads. The direction of flow in the
turbocharger cooling circuit is reversed by
this.
Rear coolant pipe
Due to this reversal of the direction of coolant
flow, coolant is drawn in via the cylinder heads
(large cross-sections), which means that any
vapour bubbles which develop are expelled
from the exhaust gas turbocharger lines.
The electrical coolant circulation pump again
draws in coolant along the rear coolant pipe,
thereby recirculating the coolant.
Thermoswitch for additional coolant
function F95
Radiator fan thermoswitch
F18/F54
SSP 198/10
10
Electrical
coolant
circulation pump
V51
Fan control
The control unit for radiator fan V293 regulates
the output of the radiator fan and controls the
continued coolant circulation. The induced-air
fan V7 and the forced-air fan V177 are
activated simultaneously.
Forced-air fan V177 is located upstream of the
condenser, water cooler and visco fan. It
assists the visco fan.
The electronic power control
The various fan settings are executed by an
electronic power control.
The fan motors are operated periodically, the
length of the operating cycle depending on the
fan setting selected. Fan output level is
controlled via pulse-width-modulated outputs.
Should a fan fail, the radiator fan control unit
increases the speed of the fan motor still
available.
SSP 198/50
Advantages of the power control:
•
The series resistors previously used for
power control are no longer required.
•
Lower power consumption in lower fan
settings.
•
Safety functions.
The power supply is protected by a
fuse on the 8-socket relay plate. For
the correct fuse rating, please refer
to wiring diagram.
Vehicles equipped with an air
conditioner require a higher fuse
rating than vehicles without an air
conditioner.
Control unit for radiator fan
attached to front right
vehicle side member
8-socket relay plate
SSP 198/55
Fuse, terminal 30
Fuse, terminal 61
11
Engine
Electric circuit of fan control:
Air-conditioning pressure switch F129
1 23
F18
V293
*
*
F54
P
F129
P
*
F95
only for vehicles with air conditioner
SSP 198/17
V51
V7
V177
_
M
M
_
M
_
for vehicles with air-conditioning system:
Integrated in the pressure switch for air
conditioner F129 is the high-pressure switch
for activating a higher fan setting.
The pressure switch is mounted below the
right-hand headlight behind the bumper.
Components:
F18/F54 Radiator fan thermoswitch
F95 Thermoswitch for continued coolant
function
F129 Pressure switch for air conditioner
(only for vehicles with air conditioner)
V293 Control unit for radiator fan
V7 Radiator fan (induced-air fan)
V51 Continued coolant circulation pump
V177 Fan 2 for radiator (forced-air fan)
(only for vehicles with air conditioner)
1 Terminal 30, positive supply via fuse
on 8-socket relay plate
2 Terminal 61, D+ (alternator) via fuse on
8-way relay
3 Fan activation (only for vehicles with
air conditioner)
12
Function of fan circuit
(for vehicles with air-conditioning
system)
4 fan settings are possible:
The electrical coolant function.....
Fan speed 1......
is activated by coolant pump thermoswitch
F95.
The fan motors and continued coolant
circulation pump V51 are activated.
The fan motors run at min. output (40%).
The continued coolant function is
only activated if the “engine not
running“ signal is picked up at
terminal 61. The continued coolant
function period is limited to 10
minutes.
is requested by radiator fan thermoswitch F18
or by the air-conditioning control panel.
The fan motors run at 50% output.
Fan speed 2......
Fan speed 3......
Fan speeds 1, 2 and 3 are only
activated if the “engine running“
signal is picked up at terminal 61.
is activated by air-conditioning system
pressure switch F129.
The fan motors run at 85 % output.
is activated by radiator fan thermoswitch F54.
The fan motors run at full output.
13
14 15
SSP 198/49
Engine
Engine lubrication
The oil circuit of the 2.7-litre V6 biturbo engine largely corresponds to that
of the 3rd V6 engine generation.
In addition, the two exhaust gas turbochargers are supplied with
pressurised oil from the main oil gallery via a distributor piece. The oil is
returned directly to the oil sump.
The oil cooler was adapted to withstand the higher thermal stresses in
comparison with a naturally aspirated engine.
A new feature of the biturbo is
the “integrated oil supply“ (see
next page).
to oil filter/oil cooler
Spring-loaded slipper
(chain tensioner)
Main oil gallery
Oil retention valves
Bypass valve
Filter element
Bearing cap
Oil groove
Oil temperature
sender
Oil pressure switch
Restrictor
Oil retention
valve
distributor piece
The oil circuit
A duocentric oil pump draws in the oil
through a coarse filter. Located in the
pressure chamber of the pump is a
pressure relief valve which protects
downstream components against
pressure peaks during cold starts.
The oil is fed to the oil filter via the oil
cooler. After passing an oil retention
valve, the oil flows through the filter
element. A bypass filter is connected in
parallel with the filter element.
The oil subsequently reaches the main
oil gallery. A branch line is routed to the
oil pressure control valve (clean oil
side).
The following components are supplied
with oil from the main oil gallery:
- the four crankshaft bearings
- the two exhaust gas turbochargers
via an oil distributor line
- the three pairs of piston spray jets via
a spray jet valve
- the cylinder head of cylinder bank 1
via an oil retention valve
The cylinder head of cylinder bank 2 is
supplied through a separate bore from
crankshaft bearing 2 via an oil retention
valve also.
First of all, the camshaft adjustment
valve is supplied with oil from the inlet
drilling in the cylinder head. After the oil
has passed by a restrictor, it is
channeled via the cylinder head main
gallery to the hydraulic valve tappets
and the camshaft bearings.
Exhaust gas turbocharger
Bypass filter
Oil pressure relief valve
from oil filter/oil cooler
Oil pressure
control valve
Induction filter
Oil pressure relief valve
from oil filter/oil cooler
to oil filter/oil cooler
Engine
The component parts of the oil circuit
The oil pump ......
is an internal gear pump. It is attached to the
crankcase as a separate component.
The oil pump is designed in such a way that it
projects deep down into the oil sump and is
immersed completely in the engine oil when
the oil level is correct. This prevents the oil
pump running dry.
The oil pump, in combination with the
extremely short intake path, enables oil
pressure to build up more quickly and safely,
particularly during cold starts.
The oil pump is driven by the crankshaft by
means of a single chain.
A spring-loaded flat plate produces the
necessary tension.
Oil pressure limiting valve
Oil pressure control valve
SSP 198/57
A new feature of the oil pump is the chain
guard made from sheet steel. It encapsulates
both the chain wheel and the chain over a large
area.
This reliably prevents oil frothing and the
problems associated with this.
The oil cooler ......
is integrated in the primary flow. By increasing
the capacity and optimising the flow
resistance, the entire oil flow can be routed
through the oil cooler. Unlike the V6 naturally
aspirated engine, a bypass is not required.
Chain guard
The oil filter ......
contains an oil retention valve, the filter
element, a bypass filter and the filter bypass
valve. The latter has the task of maintaining
engine lubrication via the bypass filter if the
filter element becomes clogged up or if the oil
has a high viscosity.
The spray jets valve ......
opens up the oil flow to the piston spray jets if
the oil pressure is greater than 1.8 bar.
Reason: at low oil viscosity and low engine
speeds, the oil pressure would otherwise drop
below the minimum permissible level. That
aside, piston cooling is not necessary at low
engine speeds.
16
The oil pressure control valve ......
The oil retention valves ......
regulates the engine oil pressure. It is
integrated in the oil pump housing. The oil
quantity “regulated“ by the oil pressure
control valve is fed to the suction side of the
oil pump.
This helps to optimise efficiency.
The oil pressure limiting valve ......
is a pressure relief valve. It is located inside the
oil pump housing and opens when the oil
pressure rises too high (cold start). If an
excessively high oil pressure builds up,
various component parts of the oil circuit (e.g.
oil filter, oil cooler) may be damaged. Also,
there is the possibility of the inlet and exhaust
valves opening or no longer closing, due to
“bulking“ of the hydraulic tappets. The knockon effect of this is that the engine can no
longer be started or cuts out.
prevent the oil running out of the oil filter and
the cylinder heads and back into the oil sump
while the engine is stationary.
The restrictors ......
prevent “flooding“ of the cylinder heads. At
high engine speeds, an excessively large
amount of oil enters the cylinder heads and
has to be returned to the oil sump via the oil
return drillings. The restrictors reduce the oil
flow and thereby ensure that return flow takes
place.
The “integrated oil supply“ ...
will also be adopted for all V6 5V naturally
aspirated engines.
Each camshaft bearing is supplied via a
drilling stemming from the cylinder head main
gallery.
The oil is fed along a bolt shaft in the bearing
cap to a transverse drilling.
A lubrication groove distributes the oil
throughout the camshaft bearing. It is no
longer necessary to run a pipe to the
individual bearing caps.
Advantages:
•
Fewer components
•
Quick and even oil supply
•
No additional installation work necessary
•
Lower cost
Transverse drilling
SSP 198/58
Cylinder head main gallery
17
Engine
Front view of engine
Hall sender G163
Charge air cooler
Intake-air temperature
sender G42
Knock sensor G61
Knock sensor G66
Camshaft adjustment
valve N208
Charge air cooler
SSP 198/51
18
Alternator
Power assisted steering
pump drive
Visco fan
Oil pressure
switch
Oil filter
Air-cond. compressor
Rear view of engine
Hall sender G40
Thermoswitch for
continued cooling
function F95
Pressure limiting
valve
Distributor piece
Coolant temperature sender F18/F54
Camshaft adjustment
valve N205
Exhaust gas
temperature sender
G235 (with evaluation
electronics)
SSP 198/52
Lambda probe
G108
Prim. catal. converter Prim. catal. converter
Exhaust gas temperature
sender G236 (with
evaluation electronics)
SAC clutch pressure plate
Lambda probe G39
19
Engine
Top view of engine
Solenoid valve for charge
pressure control N75
Camshaft
adjustment valve
N205
Injector
Solenoid valve for
activated charcoal
Divert air valve for
turbocharger N249
Fuel pressure regulator
Injector
Hall sender G163
20
Divert air valve
Charge pressure
sender G31
SSP 198/54
Divert air valve
Camshaft adjustment
valve N208
Throttle valve
control part
View of engine from left
Injector
Pressure control valve
Individual ignition coil
Prim. catal. converter
Charge air cooler
Oil filter
SSP 198/53
Exh. gas turbocharger
Oil cooler
Pressure unit for
wastegate flap
21
Engine
Air ducting
Fresh air is induced by the combined air filter
and air mass meter and distributed to the two
exhaust gas turbochargers by the air
distributor.
The air distributor is made of plastic.
Advantage:
•
Lower weight
•
The intake air is heated to a lesser degree
by the engine
The air, which is compressed and thus heated
by the exhaust gas turbocharger, is fed to the
charge air coolers.
Air filter
Air mass meter
Cooling air intakes in the bumper and air vents
in the wheel housing liners ensure that a
sufficient amount of air flows through the
charge air coolers.
Advantage of charge air cooling:
•
Cooled air has a higher density, and this
means improved volumetric efficiency.
•
The lower temperature reduces knock
tendency also.
The compressed air streams then converge
upstream of the throttle valve control part and
distributed to the individual cylinders in the
intake manifold.
Exhaust gas turbocharger
Air distributor
SSP 198/04
22
Throttle valve control part
Charge air cooler
Charging
Two
water-cooled exhaust gas turbochargers
with wastegate are used for charging.
The charge pressure of both exhaust gas
turbochargers is controlled via the common
charge pressure control valve N75.
Advantages of the biturbo technology:
•
The exhaust gas turbocharger is smaller,
which means better response due its
reduced mass.
•
Higher charge pressure at low engine
speeds.
•
The exhaust gas turbochargers are located
outside the V-angle due to the high
temperatures they reach. This advantage of
this arrangement is that the intake air is not
heated up additionally and the subassemblies are not subjected to so much
thermal stress.
•
Since the turbochargers are flanged
directly onto the exhaust manifold, the
exhaust gases travel less distance and
there is less temperature loss.
•
As a result, the catalytic converters are able
to heat up more quickly and the efficiency
of the exhaust gas turbocharger is
improved by the favourable air-flow.
The turbochargers must be replaced
in pairs
To maintain a synchronous air-flow
through the two chargers, it is
important to observe this instruction
to account for manufacturing
tolerances.
Service personnel are
not
permitted
to adjust the linkage to the wastegate
flap.
Exhaust manifold
to exhaust system
SSP 198/32
Turbine housing
Compressor housing
Charge press. side
of exh. gas turbocharger
Pressure unit for actuating
wastegate flap
Control pressure from
solenoid valve for
charge pressure
control
Intake side of exhaust
gas turbocharger
23
Engine
Exhaust system
The exhaust manifolds are designed as pipe
elbows with insulated air gaps.
Advantage:
•
Less heat loss of the exhaust gas and less
heat radiation in the engine compartment
•
Weight saving
Located downstream of each exhaust gas
turbocharger is a primary catalytic converter
close to the engine (metal substrate) .
Advantage
•
The catalytic converters quickly reach a
state of readiness for operation after a cold
start
The large-surface area main catalytic
converters (ceramic substrate) are located
under the vehicle floor.
Exhaust manifold
A new generation of probes is used
in this engine.
The “planar lambda probe“ is an
improvement on the finger-type
lambda probe (refer to chapter on
“Sensors”).
Advantage:
•
Short warm-up time
•
Less heating energy demand
•
Long service life
•
More stable control
characteristic
Air-gap-insulated pipe elbow
Wire mesh ring acting
as a spacer
Inner pipes
Outer shell
Lambda probe
SSP 198/33
Prim. catal. converterMain catalytic converter
24
Pneumatically controlled systems
In the Biturbo, 4 systems are pneumatically
controlled:
•
Charge pressure control
The Motronic ME 7.1 activates the solenoid
valve for charge pressure control N75 and
regulates the charge pressure via the
wastegate.
•
Divert air control in overrun
The Motronic ME 7.1 activates the electric
divert air valve for the turbocharger and
opens the pneumatic divert air valves using
this vacuum.
Divert air valve for
turbocharger N249
Non-return valve (divert
air control in overrun)
•
ACF system
The Motronic ME 7.1 activates the solenoid
valve for the activated charcoal canister
and regulates the fuel vapour feed rate to
the engine via the vacuum.
•
Crankcase breather
The crankcase breather controls the return
of oil vapours to the engine via two
mechanical valves.
Divert air valve
(pneumatic)
For exact the line routing, please refer
to the Workshop Manual.
Non- return valves (ACF system)
Solenoid valve for activated
charcoal canister N80
SSP 198/31
Distributor piecePressure control valve
Solenoid valve for charge
pressure control N75
25
Engine
Charge pressure control
The air mass required to develop a specific
level of torque is determined by means of an air
mass calculation and produced by controlling
the charge pressure as required.
For safety reasons, the engine in the biturbo
regulates the charge pressure, and not the air
mass as is the case with the 1.8-litre 4-cylinder
turbocharged engine.
The charge pressure is measured by charge
pressure sender G31.
The Motronic regulates the charge pressure of
both turbochargers via the solenoid valve for
charge pressure control G31.
Charge pressure
Atmospheric pressure
If a defect occurs in one of the cylinder banks
(e.g. melting of the catalytic converter or
blockage of the exhaust system), a purely air
mass-oriented charging system would still try
to provide the computed air mass.
This would lead to an excessively high charge
pressure.
In any case, the charge pressure control
prevents an excessively high charge pressure
building up inside the intake system.
Control pressure
SSP 198/08
26
Solenoid valve for charge
pressure control N75
Charge pressure sender G31
The solenoid valve for charge pressure control
N75 changes the opening time to atmospheric
pressure according to the signals it receives
from the engine control unit (duty cycle).
Thus, a control pressure is produced by
modulating the charge pressure and
atmospheric pressure. This pressure acts on
the pressure unit for the wastegate.
The wastegate is kept closed in a
depressurised state by a spring inside the
pressure unit . The entire exhaust gas flow is
routed via the turbine, and a charge pressure is
built up.
The control pressure counteracts this spring
force and opens the wastegate. Part of the
exhaust gas flow is fed from the wastegate
past the turbine, and the charge pressure stops
rising.
Turbine wheel
to catalytic converter
Wastegate flap
(open)
Exhaust gas from
combustion chamber
Control pressure from solenoid
valve for charge pressure control
pressure unit N75
If there is no flow, N75 is closed and the charge
pressure acts directly on the pressure unit. The
waste gate opens even if the charge pressure
is low.
Impeller
Intake air
to
combustion
chamber
SSP 198/66
charge pressure to solenoid valve
for charge pressure control N75
Solenoid valve for
charge pressure
limitation N75
If the charge pressure control fails, the charge
pressure is thus limited to a “basic charge
pressure“ in order to prevent the maximum
permissible charge pressure being exceeded.
This results in a loss of performance.
The “basic charge pressure“ is the charge
pressure (approx. 300 - 400 mbar) which is
achieved without regulation (mechanical
charge pressure).
Atmospheric
pressure from
distributor piece
Restrictor
SSP 198/67
Charge pressure from compressor housing
Control
pressure to
pressure unit
Passage in no
flow state
27
Engine
Divert air control in overrun
To avoid pumping the exhaust gas
turbochargers when a sudden transition from
high load to overrun is made, two divert air
valves are used.
The Motronic also activates the
two pneumatic divert air valves by
an
means of
valve, the divert air valve for
turbocharger N249.
Advantage:
•
Controlled opening of the
divert air valves reduces the
noise level in the induction
tract and reduces fuel
consumption.
with flow
without flow
electrical changeover
Divert air valve for turbocharger N249
The divert air valve N249, in combination with
the vacuum reservoir, enables the divert air
valves to operate independently of the intake
manifold pressure.
The system is designed in such a way that the
pneumatic divert air valves continue to be
opened by the intake manifold pressure if the
electrically actuated divert air valve N249 fails.
Vacuum reservoir (inside
wheelhousing on the left)
Non-return valve
28
SSP 198/05
Divert air valve (pneumatic)
ACF system
Integrated in the lines of the ACF systems are
the solenoid valve for activated charcoal
canister N80 and two non-return valves.
The engine control unit, assisted by solenoid
valve N80, regulates the return rate of the fuel
vapours from the ACF canister.
The Motronic operates the solenoid valve
cyclically using a pulse duty cycle.
The non-return valves control the return of fuel
vapours, depending on operating state.
ACF canister
Solenoid valve for activated charcoal canister N80
Vacuum in intake manifold:
Non-return valve 1 open. Fuel vapours return
to intake manifold.
charge pressure in intake manifold:
Non-return valve 2 open. Fuel vapours return
upstream of exhaust gas turbocharger.
For the exact line routing, please refer
to the Workshop Manual.
SSP 198/06
Non-return valve 1
Non-return valve 2
Vacuum in intake manifold
Charge pressure in intake manifold
29
Engine
The crankcase breather ...
...comprises a distributor piece, a pressure
limiting valve, a non-return valve and the
associated hoses.
The oil vapours and “blow-by“ gases from the
cylinder heads and the crankcase converge in
the distributor piece.
The pressure limiting valve and the non-return
valve control the return of these vapours and
gases to the engine, depending on the intake
manifold pressure.
Vacuum in intake manifold:
The oil vapours and “blow-by“ gases return
via the non-return valve in the intake manifold.
charge pressure in intake manifold:
The oil vapours and “blow-by“ gases return
via the pressure limiting valve in the air
distributor.
Distributor piece
The pressure limiting valve limits the vacuum
in the crankcase. If the vacuum in the
crankcase exceeds a defined value, the
diaphragm is drawn over the connection
against the force of the spring and closes the
connection. The valve is designed in such a
way that it allows a small quantity to pass
through when closed. This prevents the engine
oil being drawn into the intake tract and has no
adverse effects on engine breathing.
The term “blow-by“ gases refers to
the gases which escape from the
combustion chamber past the piston
rings.
from
Pressure limiting valve
distributor
piece
SSP 198/07
30
Air distributor
to air
distributor
Connection
Diaphragm
Non-return valve
Subfunctions of the Motronic
The Motronic consists of known and new subfunctions:
Sequential injection
Charge pressure control
(see chapter on “Engine” pp. 26 and 27)
Stereo lambda control
λ
Mapped ignition
Motronic ME 7.1
Cylinder-selective knock control
Static high-tension distribution with 6 individual ignition coils
ACF system
Torque-oriented engine management
Electrically actuated throttle valve (Electronic accelerator)
Cylinder bank-specific exhaust gas temperature control
Mapped variable valve timing (intake camshaft adjustment)
(see chapter on “Engine” p. 8)
New
New
New
New
SSP 198/44
31
Actuators
Heater for lambda probe
(bank 1) Z19 and (bank 2) Z28
Divert air valve for turbochargers
Camshaft adjustment valve
(bank 1) N205 and (bank 2) N208
Throttle valve control part J338
with throttle valve drive G186
Solenoid valve for
charge pressure control N75
Solenoid valve for activated charcoal
canister N80
Output stage (bank 1) N122 and
ignition coils N (cyl. 1), N128 (cyl. 2)
and N158 (cyl. 3)
Injectors (bank 1) N30, N31, N32
Fuel pump relay J17 and
fuel pump G6
Output stage 2 (bank 2) N192 and
ignition coils N163 (cyl. 4), N164 (cyl. 5)
and N189 (cyl. 6)
Fault lamp for electric
throttle control K132
Auxiliary signals
Engine speed sender G28
G163
Throttle valve control part J338
throttle valve drive G186
Intake air temperature sender G42
Charge pressure sender G31
G235 and (bank 2) G236
switch F 47
Clutch pedal switch F36
Auxiliary signals
SSP 198/14
EPC
Injectors (bank 2) N33, N83, N84
Hot-film air mass meter G70
Control unit for Motronic J220
Altitude sender F96 is
integrated in the engine
control unit.
Diagnosis
Subsystems of the Motronic
Torque-oriented engine
management
The Motronic ME 7.1 has a torqueoriented functional structure.
This is made possible by the new
electronic accelerator function.
External torque requests
• Driver inputs
Making allowance for efficiency and the
emissions standards, the engine control unit
coordinates the external and internal requests
and meets them by adjusting the available
control variables accordingly.
Internal torque requests
• Starting
• Idling speed control
• Catalytic converter
heating
• Power limiter
• Driving comfort
• Components
protection
• Engine governing
Control variables
influencing torque
• Driving
dynamics
• Driving
comfort
• Cruise control
system
SSP/198/15
Coordination of
torque and
efficiency requests
in engine control
unit
Throttle valve
angle
Charge pressure
Ignition angle
Injection cut-out
Injection time
33
Subsystems of the Motronic
Torque-oriented
functional structure
In comparison with previously known
systems, the ME 7.1 is not confined to the
output of torque variables to the networked
control units (ABS, automatic gearbox), it also
uses these physical variables to calculate
control variables.
Prioritisation of
charging path
All - internal and external - torque demands
are combined, and a nominal torque is derived
from this.
To translate the nominal torque into actions,
the control variables are co-ordinated with
regard to consumption and emissions so as to
optimise torque control.
Nominal charging
moment
Conversion of
torque into
charge
Calculation of
throttle valve
opening
Nominal charge
Throttle valve
angle
External and
internal
torque
requests
SSP 198/75
Prioritisation
of crankshaft-
synchronous
path
Actual charge
Calculation of
efficiency and
torque reference
variables
Calculation of
crankshaft-
synchronous
intervention
Nominal inner
torque
Charge
pressure-
control
Nominal intake
manifold
pressure
Charge
pressure
(Wastegate)
Ignition angle
Injection cutout
Injection time
34
The control variable calculation is subdivided
into two paths
Prioritisation of
charging path
Path 1
The charging path regulates the control
variables which influence charging:
• Throttle valve angle
• Charge pressure
The air mass necessary to develop a specific
torque is determined by means of a
“calculation model“ and is made available
1
along path
Path
2
.
is used to set the injection quantity or
cylinder cut-out necessary under the given
circumstances and the optimal ignition angle.
Prioritisation
of crankshaftsynchronous
path
Path 2
All control actions which influence torque
regardless of charging are combined in the
crankshaft-synchronous path:
• Ignition angle
• Injection cut-out
• Injection time
By and large, long-term torque requests are
fulfilled along path
Path 2
is particularly well suited to meeting
1
.
short-term torque requests, which usually
have a torque-reducing effect.
35
Subsystems of the Motronic
Electrically actuated throttle
valve (electronic accelerator)
With the Motronic ME 7.1, Audi is
using an electrically actuated
throttle valve for the first time.
There is no longer any need for a
mechanical accelerator cable
between the accelerator and
throttle valve. This has been
replaced by an electronic control
system (drive-by-wire).
The system comprises the following
components:
• Accelerator position sender
• Engine control unit
• throttle valve control part
CPU = Control Processing Unit
The accelerator position sender records the
accelerator pedal angle and transfers it to the
engine control unit.
The engine control unit adjusts the throttle
valve by means of an electric motor. A
continuous stream of feedback signals on the
position of the throttle valve is sent to the
engine control unit.
Extensive security measures in hardware and
software format - such as twin senders, safety
module and self-monitoring computer
architecture - are integrated in the electronic
accelerator .
Engine control unit
Input signals Output signals
Throttle valve control
part J338
Throttle valve
drive G186
Accelerator position sender
SSP 198/09
Accelerator position
senders G79 and
G185
36
CPU
Safety module
Angle sender for
throttle valve drive
G187 and G188
The electronic accelerator controls the engine
output electronically and, over and above
intake-air control, offers the advantage that
functions such as idling speed control, cruise
control or engine governing can be executed
easily and comfortably.
.
Torque reduction Torque increase
The electronic accelerator is used for reducing
and increasing torque and does not adversely
affect exhaust emissions.
• Traction control system
• Engine governer
• Speed limiter
• Power limiter
• Cruise control system
• Driving dynamics control systems
The throttle valve can be opened regardless of
the accelerator position, and this serves to
reduce throttle losses.
The ideal combination of throttle valve crosssection and charge pressure produce the
necessary torque.
In this way, the throttle valve can be opened
fully while the accelerator pedal has not been
fully depressed.
• Cruise control
• Engine braking torque control
• Load change damping
(Dash pot function)
• Idling speed control
• Driving dynamics control systems
With electronic accelerator, much improved
emissions and higher fuel economy are
achieved in specific load states.
Over and above this, any accelerator
characteristic can be programmed, e.g.
gradual acceleration when driving at low
speed.
37
Subsystems of the Motronic
Accelerator position senders G79
and G185
The accelerator position sender transfers an
analog signal corresponding to the accelerator
position to the Motronic. To ensure that the
electronic accelerator functions reliably, the
accelerator position sender has two
independent potentiometers (G79 and G185).
They have different characteristic curves (see
diagram).
The control unit monitors the two senders G79
and G185 for proper functioning and
plausibility.
If a sender fails, the other sender serves as a
substitute.
The accelerator position sender transfers the
driver’s inputs to the Motronic and provides
kickdown information to the automatic
gearbox.
There is no separate switch for
kickdown information. Integrated in
the accelerator position sender is a
“mechanical pressure point “ which
conveys an authentic “kickdown feel”
to the driver.
When the driver operates the
kickdown, the full-load voltage of the
accelerator position sender is
exceeded. If a voltage defined in the
engine control unit is attained in the
process, this is interpreted as a
kickdown and transferred to the
automatic gearbox (via CAN-Bus).
The accelerator position senders for
the manual gearboxes and automatic
gearboxes are identical. Kickdown is
enabled or disabled via the
accelerator limit stop (refer to chapter
on “TDI engines”).
Lever
Ω
Resistance in
LL
SSP 198/25
G79
G185
Accelerator travel
38
SSP 198/12
Accelerator
Acc. position sender
Self-diagnosis/emergency
running
If a fault occurs in the accelerator position
sender or the wiring, two emergency running
programs can be run depending on fault type.
Emergency running program 1
If an accelerator position sender fails:
• Accelerator position limited to a defined value.
• If a full load is predefined, the power output is
increased slowly.
• In the case of implausible signals between G79
and G185, the lower value is used.
Prerequisite:
The idling speed position must be learnt once
by the intact sender.
• The signal supplied by brake light switch for
brake pedal switch F47 indicates the idling
speed.
• Comfort functions (CCS) are prohibited.
• The fault lamp for electric throttle control K132
comes on.
At idling speed, the accelerator
position senders G79 and G185 are
not diagnosed.
If the plug of the accelerator position
sender drops off, no fault is stored in
the control unit.
The fault lamp for electric throttle
control K132 does not come on.
The engine runs at idling speed and
does not respond to the accelerator
pedal.
Emergency running program 2
If both accelerator position senders fail, driver
input recognition is not possible:
• The engine only runs at idling speed.
• The fault lamp for electric throttle control K132
comes on.
Safety function:
For safety reasons, the throttle valve
is closed as far as a defined angular
position when both the accelerator
pedal and the brake pedal are
depressed.
If the brake is pressed first followed
by the accelerator pedal, the driver
input (torque request) is executed.
39
Subsystems of the Motronic
throttle valve control part J338 with throttle valve drive G186, angle
senders 1 G187 and 2 G188 for throttle valve drive
The throttle valve control part comprises...
... throttle valve housing with throttle valve
... throttle valve drive G186 with reduction
gear
... angle senders for throttle valve drive
G187 and G188
Activated by the engine control unit, the
throttle valve drive controls the air-flow rate
necessary to develop the required torque.
Feedback on momentary throttle valve
position is provided by two potentiometers
G187 and G188.
Throttle valve drive G186
(Electric throttle control)
For safety reasons, two angle senders
(redundancy) are used. They have opposite
impedance characteristics (see diagram).
If an angle sender fails, the second sender
maintains the electronic accelerator function
via an emergency running program.
Angle senders G187 and G188 cannot
be replaced separately. The throttle
valve control part may not be opened.
Redundancy means: superfluous,
non-essential.
Ω
SSP 198/27
G188
Throttle valve housing
with throttle valve
SSP 198/28
40
Resistance in
Angle senders for throttle valve
drive G187 and G188
0 100%
Throttle valve opening in %
Housing cover with electrical
connections
G187
Functional positions of throttle valve control part (linear
representation)
The engine control unit recognises four key functional positions of the throttle valve control part.
• The lower mechanical limit stop
The throttle valve is closed. This
position is required to adapt the angle
sender.
• The lower electrical limit stop
is defined by the control unit and is
located just below the lower
mechanical limit stop. During
operation, the throttle valve closes no
further than the lower electrical limit
stop. This prevents the throttle valve
working its way into the throttle valve
housing.
Lower mechanical limit stop
SSP 198/24
Position of lower electrical limit stop
• The emergency running position
is the position of the throttle valve in
the deenergised state and ensures that
air flow is sufficient if any of the
relevant electronic accelerator functions
fails. Idling speed is higher - approx.
1000 rpm - and uneven.
Very limited vehicle operation is
possible.
SSP 198/22
Emergency running position
SSP 198/21
41
Subsystems of the Motronic
• The upper electrical limit stop
is defined in the control unit does not
need to be learned.
As in the
shaft diameter is greater than
the thickness of the throttle
butterfly.
To enable the exact angular position of the throttle valve to be identified, angle senders for
throttle valve drive G187 and G188 must be learnt .
By moving the throttle valve into predefined positions, the values of the angle senders are stored
in the control unit (calibrated) and checked for plausibility. The state of the mechanics (terminals,
weak springs) in the throttle valve control part is determined by evaluating the throttle valve’s
reaction speed.
fully open position
, the
Position at upper electrical limit stop
SSP 198/23
Upper mechanical limit stop
Basic adjustment (adaption) ...
... involves not only learning the throttle
valve position, but also a complete check of
the throttle valve control part
... can be performed using the following
three methods:
•
manually
switched on for at least 24 minutes without
operating the starter or accelerator.
automatically -
•
is acknowledged.
•
specifically -
measured value block 60 (refer to Workshop
Manual)
42
- provided the ignition has been
provided the need for adaption
by initiating basic setting 04 in
Adaption conditions
For basic setting (adaption), the test
conditions described in the
Workshop Manual must be met.
The basic setting routine will be
cancelled if the test conditions are
not fulfilled
while
it is in progress.
Self-diagnosis/emergency running mode
If a fault occurs in the throttle valve control part or in the wiring, three emergency running
programs can be run, depending on fault type.
Emergency running program 1
If an angle sender for throttle valve drive fails
or an implausible signal is received:
• Torque-increasing requests on engine, e.g. CCS,
EBC (engine braking control) are suppressed.
• The fault lamp for electrical throttle control K132
comes on.
Emergency running program 2
If the throttle valve drive fails or malfunctions:
• The throttle valve drive is switched off and the
throttle valve goes into the emergency running
position. This results in considerable loss of
power, increased idling speed and possibly also
rough idling .
• Driver inputs are executed as far as possible via
the ignition angle and charge pressure. The
engine shows little response to the throttle.
• The fault lamp for electrical throttle control K132
comes on.
Prerequisite:
An intact angle sender and plausible
air mass flow. The air mass flow is
indicated by the air mass meter and
the charge pressure sender G31.
Prerequisite:
Emergency running program 2 is only
run if both angle senders for throttle
valve drive recognise the emergency
running position.
Emergency running program 3
If the throttle valve position is not clearly
recognisable and/or if the throttle valve is not
definitely known to be in the emergency
running position:
• The throttle valve drive is switched off and the
throttle valve goes into the emergency running
position. This results in considerable loss of
power, increased idling speed and possibly also
rough idling.
• The engine speed is limited to approx. 1200 rpm
by restricting the injection.
• The fault lamp for electric throttle control K132
comes on.
Repair work may not be performed on
the throttle valve control part J338! If
G186, G187 or G188 becomes faulty,
unit J338 must be replaced
completely and a
basic setting
performed.
43
Subsystems of the Motronic
Fault lamp for electric throttle
control K132
Faults in the Electronic Accelerator System are
detected by the self-diagnosis and indicated
via the separate EPC fault lamp. At the same
time, an entry is made in the fault memory.
When the ignition is turned on, the fault lamp
comes on and must go out again after 3
seconds if a fault state does not exist.
Fault lamp K132 is activated directly by the
engine control unit via an earth potential.
If a fault occurs in the Electronic Accelerator
System, an appropriate emergency running
program will be activated (refer to Accelerator
position sender and throttle valve control part).
EPC
stands for Electronic Power
C
ontrol.
44
120
60
180
°C
SSP 198/47
EPC
90
120
4
3
5
2
EPC
1
12
93
6
60
°C
6
7
1/2
1/1
8
50
30
10
80
120
140
100
0
160
180
260
200
220
12
16
8
Volt
In keeping with our policy of continuous product
improvement, the accelerator position sender
has been replaced by the
module
.
accelerator pedal
The accelerator pedal module has already been
used in other vehicle models within the Group.
The accelerator pedal module combines the
accelerator pedal and the accelerator position
sender as a unit.
The mechanics of the accelerator pedal module
are located inside the module housing.
Sensors G79 and G185 are located in the
housing cover.
For manual gearbox:
Stop buffer
For automatic gearbox:
Pressure element for
conveying the authentic
feeling of a kickdown
Advantages of the accelerator pedal module:
• Compact, lightweight, easy to assemble
• Modular technology
• Inexpensive to manufacture
Module housing
Housing cover and
sensors
SSP 198/34
45
Subsystems of the Motronic
Exhaust gas temperature control
A new feature of Audi automobiles
is a function which monitors
exhaust gas temperature over the
entire engine speed range.
For turbocharged engines, the maximum
permissible exhaust gas temperature is a key
design criterion.
To protect the exhaust gas turbocharger and
the exhaust manifold, the exhaust gas
temperature should not exceed 1000 °C for a
lengthy period of time.
Since many of the components which
influence the exhaust gas temperature have
tolerances, thermodynamic adaptation
previously took place at 950 °C for safety’s
sake.
This was achieved by enriching the air/fuel
mixture.
The exhaust gas temperature is recorded in a
cylinder-bank-specific manner by the two
exhaust gas temperature senders G235 and
G236.
The Motronic controls the exhaust gas
temperature to 980 °C by enriching the air/fuel
mixture .
It is therefore possible to largely dispense with
the prophylactic enrichment process that has
been standard practice until now.
The mixture is only enriched...
... when necessary and
... to the extent necessary.
This means that engine operation with lambda
= 1 is possible up to high load and engine
speed ranges.
Advantage:
• Improved efficiency and reduction of fuel
consumption as well as exhaust emissions.
Exhaust gas temperature sender
G235
G236
SSP 198/26
46
Injectors
Engine control unit
Exhaust gas temperature sender
G235 and G236
To facilitate exhaust gas temperature control,
the exhaust gas temperature must be recorded
to a high degree of accuracy.
An accuracy of ± 5 °C is achieved in the
measurement range from 950 °C to 1025 °C.
evaluation electronics
The exhaust gas temperature sender is located
inside the exhaust manifold upstream of the
exhaust gas turbocharger.
It comprises a measuring sensor and
evaluation electronics.
The measuring sensor and the control unit are
permanently connected by means of a
shielded, heat-resistant wire.
The evaluation electronics convert the signal
which the measuring sensor generates into a
pulse-width-modulated signal (PWM signal).
This is a square-wave signal with a fixed
frequency and a variable pulse duty factor.
The pulse duty factor is expressed as a
percentage . The measurement range extends
≥
from
10% to ≤90%.
A specific pulse duty factor is assigned to each
temperature (refer to diagram).
Substitute function and self-diagnosis:
A pulse duty factor of <1% or >99% is
recognised as a fault.
A fault is detected as of a certain enrichment
quantity.
If a sender fails, the charge pressure is reduced
to a safe level and an emergency enrichment
characteristic (engine speed-dependent) is
used.
Meas.
SSP/198/13
Exhaust gas temperature sender
90%
70%
50%
30%
10%
Pulse duty factor
945°C
950°C
960°C
SSP 198/56
970°C
980°C
990°C
1000°C
1010°C
Exhaust gas temperature
1025°C
1030°C
47
Notes
48
Sensors
The following chapter presents the new features of the sensors, provided that they have not
already been described in the chapter on Subsystems of Motronic.
Charge pressure sender G31
The charge pressure sender is located
upstream of the throttle valve control part.
The Motronic supplies the sender with a
voltage of 5 volts and earth.
The signal which the sender generates is a
pressure- proportional voltage ranging from 0
to 5 volts.
At atmospheric pressure (at sea-level), the
voltage is approx. 2.5 volts.
The signal is used for charge pressure control.
The Motronic also needs information on
charge pressure so that it can take countermeasures if the maximum permissible
pressure is exceeded.
Substitute function and self-diagnosis:
If sender G31 fails, the charge pressure is
controlled via the characteristic curve (engine
speed-dependent). This will result in a
deficiency of engine power.
SSP 198/29
Charge pressure sender G31
The altitude sender F96 ....
... is integrated in the engine control unit, as is
normally the case with turbocharged engines.
... is required to control the charge pressure. In
conditions of decreasing air pressure (lower
density), the charge pressure is reduced to
prevent the turbocharger overspeeding.
... influences the air/fuel mixture composition
at engine start-up. The starting mixture is
leaned down with rising altitude.
Substitute function and self-diagnosis
If a signal fails, the charge pressure is reduced
to a safe level, which results in a deficiency of
engine power.
Adaption of the injection quantity at start-up
no longer takes place.
The fault message “Control unit defective“ is
displayed in the self-diagnosis.
49
Sensors
Hot-film air mass meter G70
The hot-film air mass meter
operates on the same principle as
before.
In certain engine operating states,
pulsations occur in the intake tract,
reversing the air flow - and this
gives rise to measurement errors.
The hot-film air mass meter is designed in such
a way that it is able to recognise this returning
air flow (pulsation fault).
This more exact method of intake air
measurement in all operating states improves
engine management and reduces exhaust
emissions.
The hot-film air mass meter is a thermal
flowmeter. A partial airflow from the
measuring pipe is fed past the sensor element
through a measuring channel in the air mass
meter housing.
The ascertained temperature values are
evaluated in the evaluation electronics. The
Motronic applies a voltage proportional to the
air mass to the air mass meter. This voltage is
needed to calculate the injection period and of
actual engine torque.
Evaluation electronics
Meas.
channel
Sensor element
Substitute function and self-diagnosis:
The air mass meter detects air masses above
or below predefined limits. If the air mass
meter fails, the air mass is calculated on the
basis of a characteristic curve (throttle valve
angle and engine speed).
50
SSP 198/16
Hot-film air mass meter
The measuring principle of the return flow
recognition
The sensor element is embedded in the
mounting plate.
The sensor element comprises a diaphragm
with a heating zone and two symmetrically
arranged temperature sensors T
and T2.
1
Temperature sensors T1 and T2 indicate a
temperature difference of ∆T.
In the case of a return air flow, the temperature
difference occurs at temperature sensor T1.
The amount and direction of this difference are
therefore dependent on the incoming flow.
The heating zone is set to an overtemperature
by means of a heating resistor and
temperature sensor T2.
If there is an incoming flow, the upstream part
of the diaphragm cools down along with the
temperature sensor T1.
The temperature of the upstream temperature
sensor T2 is maintained due to the heated air in
the heating zone.
Temperature profile
Temperature difference
evaluation: ∆T = T2 - T
1
1
• Advantage: the differential signal permits a
direction-dependent characteristic which
enables the Motronic to detect a return air flow.
without incoming flow
with incoming flow
Incoming flow
SSP 198/36
Mounting plate
0
Diaphragm
T
1
Heating zone
T
T
2
Sensor element
51
Sensors
Lambda probes G39 and G108
The planar lambda probe is a further
development of the finger-type lambda probe
and has a transient response at lambda = 1.
There is a single lambda probe in the exhaust
pipe running to each of the primary catalytic
converters.
To ensure that the exhaust gases are treated
efficiently, it is important that the lambda
probe should react quickly. The lambda probe
should therefore reach its operating
temperature within as short a space of time as
possible. Its planar (= flat, elongated) design
makes this possible.
The probe heater is integrated in the sensor
element. It quickly reaches its operating
temperature despite its lower heating capacity.
Note:
At an exhaust gas temperature as low as 150
°C, the probe heater generates the necessary
minimum temperature of 350 °C.
The lambda control is ready to operate approx.
10 seconds after engine start-up.
A new generation of probes used in
the biturbo for stereo lambda
control.
Advantages:
• The warm-up period is short, which means
lower emissions during the warm-up phase
• Low heating power consumption
• More stable control characteristic
A porous, ceramic protective layer is sintered
onto the sensor element.
This layer prevents the sensor element being
damaged by residues in the exhaust gas.
It ensures that the sensor element will have a
long service life and meet the tough functional
demands.
Substitute function:
Controlled operation based on a characteristic
curve (cylinder bank-specific).
Sensor element
Section
SSP 198/37
Probe heater
52
Hall senders G40 and G163
On V-engines with variable valve
timing, a Hall sender acting as a
camshaft sensor is attached to the
left- and right-hand cylinder banks.
To permit cylinder-selective knock control and
sequential injection, cylinder 1 must be
defined precisely.
The signal which Hall sender G40 supplies
together with the signal which engine speed
sender G28 generates (incremental sender for
engine speed and reference mark) enable
ignition TDC of cylinder 1 to be identified
(synchronization of cylinder 1).
After the simultaneous input of both signals,
initial injection and ignition are enabled.
Hall sender G40
By using Hall senders G163 and G40 as
camshaft sensors, the adjustment of both
camshafts can be monitored closely and
evaluated by the self-diagnosis.
Substitute function and self-diagnosis:
If Hall sender G40 fails, Hall sender G163 takes
on the task of synchronising first cylinder.
If both Hall senders fail, it is possible to start
the engine and the engine runs with substitute
functions.
SSP 198/35
Hall sender G163
53
Sensors
Engine speed sender G28
The engine speed sender is an inductive
sender which records the engine speed and
the exact angular position of the crankshaft
(single-sender system).
Attached to the flywheel is a separate sender
wheel for the G28.
The sender wheel is designed as a segmented
wheel and is subdivided into 60 segments.
If the sender wheel moves past G28 , this
produces an alternating voltage whose
frequency changes as a factor of engine speed.
The frequency is the magnitude of the engine
speed.
To enable it to recognise the crankshaft
position, there is a gap of two segments in the
sender wheel.
Engine speed sender
The G28 recognises the engine speed.
Together with Hall sender G40, the G28
recognises the exact position of the engine
mechanics, i.e. ignition TDC of cylinder 1. The
injection and ignition timing are determined
using this information.
Substitute function and self-diagnosis:
The signal which G28 generates is checked
together with the signal supplied by the G40
for plausibility.
If the Motronic control unit does not detect any
segment gaps during 8 “phases“ of the G40,
an entry is made in the fault memory.
If the engine speed sender fails, it is not
possible to start or run the engine.
Since the G28 is an inductive sender,
the self-diagnostics are unable to
perform electrical tests (short circuit
to positive or negative or open
circuit).
Segment
gap
SSP 198/64
Sender wheel
Two mass flywheel
54
Diagram of signal of engine speed sender and Hall sender using the oscilloscope function of
VAS 5051
Hall sender G40 (bank 2)
Engine speed sender G28
Sender wheel
Software reference mark
TDC of cylinder 1
72° before TDC of cylinder 1
Diagram of signal of engine speed sender and the two Hall senders
Hall sender G40
Hall sender G163 Hall sender G40
TDC of cylinder
1436251
Engine speed sender G28
SSP 198/59
SSP 198/60
Here, the signals which G40, G163 and G28 generate are shown combined for added
clarity. A two-channel oscilloscope does not allow all three signals to be represented.
The TDC mark of the belt pulley reflects the TDC of cylinder 3.
55
Sensors
Brake light switch F and brake
pedal switch F47
Clutch pedal switch F36
Brake light switch F and
brake pedal switch F47
The information “brake operated“ is required
for the following functions:
• Function of cruise control system
• Safety interrogation of electronic accelerator
function (idling speed recognition during
emergency running mode of accelerator
position sender)
Brake light switch F and brake pedal switch F47
are combined as a unit. Both serve as
information senders for “brake operated“,
which means they are redundant (for safety
reasons).
Brake light switch F is open in the “off”
position and is supplied with voltage from
terminal 30. It serves as an additional
information input for the Motronic.
Brake pedal switch F47 is closed in the “off”
position closed and is supplied with voltage
from terminal 15. It serves exclusively as an
information input for the Motronic.
Substitute function and self-diagnosis:
The two switches are cross-checked for
plausibility by the self-diagnosis.
Please read the note on the “Safety function“
on page 39.
SSP 198/63
Clutch pedal switch F36 ...
... switches the cruise control system off.
... deactivates the load change functions during the gearshift operation. The load change
function is controlled via ignition angle intervention and throttle valve closing speed.
The clutch pedal switch is closed in the “off” position and is supplied with voltage from terminal
15.
Substitute function and self-diagnosis:
The F36 is not included in the self-diagnosis, which means that no substitute functions are
initiated.
Wrong settings, electrical malfunctions or maloperation (driver keeps foot on clutch
pedal) may result in load change jolts or engine speed overshoots.
56
Additional signals/interfaces
Additional signals/interfaces to
Motronic ME 7.1
The Motronic receives a large number of
additional signals.
The following overview shows the signal
direction and meaning referred to the Motronic
control unit
Input
signal
•
•
Output
signal
Bidirec-
tional
•
•
Signal meaning
CAN-high, data bus signal for automatic gearbox
CAN-low, data bus signal for automatic gearbox
CCS, “set/decelerate“ signal for cruise control system
CCS, “Off“ signal for without cancellation cruise
control system
The term “interfaces“ is used to
describe the control unit connections
and wiring connections of the various
control units.
•
•
•
•
•
•
•
•
CCS, “On/Off“ signal for with cancellation cruise
control system (master switch)
CCS, “Resume/accelerate“ signal for cruise control
system
Road speed signal
Immobiliser/diagnosis signal
Air conditioner compressor “On/Off“ signal
Coolant temperature signal
Engine speed signal
Fuel consumption signal
57
Additional signals/interfaces
The road speed signal ...
... is required for operation of the cruise control
system, speed limiter, load change measures,
idling speed stabilisation and internal safety
checks of the control unit (e.g. adaption
conditions).
Road speed signal (4 pulses)
1 revolution of wheel
Signal from speedometer sender (reed contact)
... is a square-wave signal which is conditioned
by the dash panel insert. The frequency of this
signal changes as a factor of road speed.
The dash panel insert transfers 4 pulses per
revolution of the wheel.
Coolant temperature signal
The engine control unit receives from the dash
panel insert a coolant temperature signal
calculated from the signal which coolant
temperature sender G2 generates and a
related temperature characteristic.
The signal is a “data message“ and is
connected to the earth potential when a
temperature of approx. 120 °C is exceeded.
In this case, the air conditioner’s operating and
display unit switches the compressor off along
the bidirectional wire designated “Airconditioner compressor On/Off“.
SSP 198/69
As of a temperature of 116 °C, the charge
pressure is reduced in order to counteract a
further rise in temperature.
If the temperature drops below a value of
approx. 116 °C, a data message is again
transferred and all actions previously
performed are reversed.
58
The “Compressor On/Off“ interface ...
... serves to provide the engine control unit
with information on the circuit state of the
compressor.
... enables the engine control unit to switch off
the compressor or inhibit start-up.
... provides a link to the air conditioner’s
operating and display unit.
The interface as a signal input:
Shortly before switching on the magnetic
coupling, the air conditioner’s operating and
display unit applies voltage to the interface.
The engine control unit then increases the
idling speed to compensate for the higher
engine load.
The interface as a signal output:
If the engine control unit applies an earth
potential to the interface, the compressor is
switched off for a defined period of time as
required.
The engine control unit switches the
compressor off in the following situations:
- After initiating basic setting (function 04)
- In certain emergency running programs
within a defined engine speed range
The immobiliser/diagnosis interface ...
... is the communication link between the
engine control unit and the immobiliser in the
dash panel insert.
... also serves as the diagnosis wire (K-wire) for
the diagnosis tester. Dialogue takes place via:
diagnosis plug ⇔ dash panel insert interface ⇔
immobiliser/diagnosis interface ⇔ engine
control unit
59
Additional signals/interface
The engine speed signal...
... is a square-wave signal which is conditioned
by the engine control unit and whose
frequency is synchronous with engine speed.
The duty factor is approx. 50%.
Three signals are transferred per revolution of
the engine.
... is required by the following system
components:
- Dash panel insert
- Automatic gearbox
- Air conditioner
3 signals
12
Segments of the sender wheel
20 40 60
3
1 revolution of engine
The CAN-high/CAN-low interfaces ...
... serve to transfer data between the control
units.
The CAN data bus (Controller Area Network) is
a serial data transfer system.
SSP 198/61
You can find detailed information
regarding the CAN databus in SSP
186.
60
The fuel consumption signal...
... is a data message which is conditioned by
the engine control unit. The sum total of the
high levels during a defined period of time
corresponds to the injected fuel quantity.
Fuel consumption signal
Signal of Hall sender G40
... is required by the dash panel insert to
calculate fuel consumption and range.
Signal at idling speed in a time grid of
50 ms/div.
The interfaces of the cruise control system (CCS) ...
... are linked to the controls on the steering
column switch.
Cruise control is executed by the
engine control unit by means of the
electronic accelerator function.
Road speed can be kept constant as
of approx. 25 kph.
The CCS must be enabled or disabled using
the “login procedure“ function (as with TDI
engines).
When the control unit is enabled, a “G“
appears in the control unit identification (refer
to Workshop Manual).
SSP 198/68
61
Functional diagram
Components:
F Brake light switch
F36 Clutch pedal switch
F47 Brake pedal switch
F96 Altitude sender (integrated in engine
control unit)
G2 Coolant temperature sender
G6 Fuel pump
G28 Engine speed sender
G31 Charge pressure sender
G39 Lambda probe (cylinder bank 1)
G40 Hall sender (cylinder bank 2)
G42 Intake air temperature sender
G 61 Knock sensor (cylinder bank 1)
G62 Coolant temperature sender
G66 Knock sensor (cylinder bank 2)
G70 Air mass meter
G79 Accelerator position sender 1
G108 Lambda probe (cylinder bank 2)
G163 Hall sender (cylinder bank 1)
G185 Accelerator position sender 2
G186 Throttle valve drive (electric throttle
control)
G187 Angle sender 1 for throttle valve drive
G188 Angle sender 2 for throttle valve drive
G235 Sender 1 for exhaust gas temperature
G236 Sender 2 for exhaust gas temperature
J17 Fuel pump relay
J220 Motronic control unit
J338 throttle valve control part
K132 Warning lamp for electric throttle
control
N189 Ignition coil, cylinder 6
N192 Output stage (cylinder bank 2)
N205 Camshaft adjustment valve 1 (cylinder
bank 1)
N208 Camshaft adjustment valve 2
(cylinder bank 2)
N249 Divert air valve for turbocharger
Z19 Heater for lambda probe
Z28 Heater for lambda probe 2
I To dash panel insert
II To dash panel insert (warning lamp)
Additional signals
1 CAN-high (automatic gearbox)
2 CAN-low (automatic gearbox)
3 „Set/decelerate“ signal for cruise
control system
4 “Off“ signal without cancellation for
cruise control system
5 “On/Off“ signal with cancellation for
cruise control system
6 Resume/accelerate“ signal for cruise
control system
7 Road speed signal
8 Immobiliser/diagnosis signal
9 Air conditioner compressor “On/Off“
signal
10 Coolant temperature signal
11 Engine speed signal
12 Fuel consumption signal
N Ignition coil, cylinder 1
N30 Injector, cylinder 1
N31 Injector, cylinder 2
N32 Injector, cylinder 3
N33 Injector , cylinder 4
N75 Solenoid valve for charge pressure
control
N80 Solenoid valve for activated charcoal
canister
N83 Injector, cylinder 5
N84 Injector, cylinder 6
N122 Output stage (cylinder bank 1)
N128 Ignition coil, cylinder 2
N158 Ignition coil, cylinder 3
N163 Ignition coil, cylinder 4
N164 Ignition coil, cylinder 5
62
Colour codes:
Input signal
Output signal
Positive
Earth
Bidirectional
63
M
31
30
15
31
_
N31
N32
N33
N80
J220
N83
N84
N30
N75
N249
N205
N208
G235 G236
G31
N N128
J17
N158 N163 N164 N189
Q
PPPPPP
QQ QQQ
A
A B
Z
Z
BBB
N122
A
B B B
1
N192
G61 G66 G188 G187 G186 G79
F47F36 F
G163 G40 G62G2 G42
K132
G185
G28G70 G39
Z19
G108
Z28
Y
+
Y
I
2 3 4 5 6 7 8 9 10 11 12
II
λ
λ
t° t°
m
l
t°t°t°
+++ +
Cruise control op. switch
from ignition lock terminal 15
to the brake lights
terminal 30a
Body earth Engine earth
Note:
For the correct fuse rating,
please refer to the current flow
diagram
Body earth
Self-diagnosis
Vehicle diagnosis, test and
information system VAS 5051
VAS 5051 has the following three operating
modes:
Vehicle self-diagnosis
• Communication via the vehicle’s diagnosis
interface
• Offers the functional capability of currently
available diagnosis testers V.A.G 1551 and
V. A. G 1552
Test instruments
• Measurement of the vehicle’s electrical
parameters (voltage, current, resistance)
and testing of diodes
• DMO (Digital Memory Oscilloscope) for
representing the voltage curves of the
various individual sensors and actuators
Guided fault finding
• Vehicle and control unit identification
• A test plan is prepared on the basis of the
fault messages issued by the the selfdiagnosis, the fault description of customer
complaints or assumptions regarding the
cause of the trouble.
You will find introductory notes and
technical information on this system
in Self-Study Programme 202.
For self-diagnosis, please use the
Workshop Manual in which the
procedure for the various individual
functions is described.
SSP 198/39
VAS 5051
64
Test box V.A.G 1598/31
The new test box V.A.G 1598/31 is used to
carry out tests on the Motronic ME 7.1.
It also allows tests to be performed while the
engine is running.
The test leads V.A.G 1598/31-1 (1
metre long) and V.A.G 1598/31-2 (2.5
metres long), which are additionally
screened, give greater flexibility and
protection against electromagnetic
interference.
Engine control unit
SSP 198/65
AS 5051VAS 5051
V
Test box V.A.G 1598/31
VAS 5051
Earth
65
Power Transmission
Self-adjusting clutch
For the biturbo engines, Audi is
using an SAC clutch pressure plate
with a wear compensation feature
for the first time.
„
C
Auxiliary spring
Housing cover
SAC
“ stands for Self-Adjusting
lutch.
Advantages:
• Constant clutch releasing loads throughout
the service life of the clutch plate.
• Greater wear reserve of the clutch plate.
Sensor plate spring
Adjusting ring
Main diaphragm spring
SSP 198/42
66
Compression spring
Problem:
As the clutch plate wears, the position of the
main diaphragm spring changes, as do the
characteristics for contact pressure and
releasing load.
The main diaphragm spring has a digressive
characteristic. To prevent the contact pressure
of the pressure plate dropping too low over a
wear range of approx. 1.5 - 2 mm, the
characteristic of the main diaphragm spring is
such that the forces initially increase as a
factor of distance travelled.
This has the knock-on effect of producing
uncomfortably high pedal forces.
Housing cover
The clutch in the biturbo engine is required to
transmit high levels of torque.
Higher contact pressures have to be applied to
compensate for the limitations on the surface
area of the clutch lining for design reasons.
This in turn results in higher releasing loads
(particularly as wear progresses).
Contact pressure characteristic
(conventional clutch )
Wear reserve
SSP 198/41
Auxiliary spring
Disengaging stop
Main diaphragm spring
Adjusting ring
Sensor plate spring
Fitting location
Contact pressure
0-1-2 1 2 3 4
Pressure plate travel in mm
SSP 198/72
Solution to problem:
If the position of the main diaphragm spring
remains constant over the entire wear range,
the associated forces will also remain
unchanged.
This effect is achieved using the new SAC
clutch pressure plate.
67
Power Transmission
Function of SAC clutch
Compared to a conventional clutch, the
following parts are new or modified:
• Sensor plate spring
• Adjusting ring with ramps (wedges) and
compression springs
• Housing cover with ramp indentations and
guides for the compression springs
• Stop for release travel (integrated in the
housing cover)
• Auxiliary spring (riveted to the housing
cover)
stop for release travel
The
travel of the release bearing and
prevents unintentional adjustment of
the adjusting ring.
auxiliary spring
The
main plate spring as of a defined
travel distance and ensures an even
force curve during clutch engagement
and disengagement.
Main diaphragm spring
limits the
counteracts the
Pressure plate
Housing cover with auxiliary spring
and s
top for release travel
SSP 198/70
Auxiliary spring
(riveted on)
Sensor plate spring
Adjusting ring with
compression springs
68
Unlike conventional pressure plates, the main
diaphragm spring mounting of the SAC clutch
is non-rigid.
Conventional clutch SAC clutch
The sensor plate spring and the adjusting ring
locate (mounting) the main diaphragm spring.
SSP 198/73
after wear
Main plate
spring mounting
after wear
Adjusting ring
Main plate
spring mounting
Position as new Position after
wear
Position as newPosition after
wear
When the clutch plate is renewed, the
adjusting ring must be turned back
(refer to Workshop Manual).
The adjusting ring on new SAC clutch
pressure plates is already reset.
69
Power transmission
Clutch disengagement process
The force of the sensor plate spring
counteracts that of the main diaphragm spring
and is rated such that the main diaphragm
spring is pressed against the adjusting ring
under normal releasing load.
If the force of the main diaphragm spring (also
refer to load diagram) is greater than that of
the sensor plate spring, the main plate spring
will not come into contact with the adjusting
ring.
Sensor plate spring
Housing cover
The compression springs rotate the adjusting
ring along the ramps in the housing cover.
In this way, lining wear is compensated and
the forces are again equalised.
Compress. spring
Ramp (wedge)
70
SSP 198/74
Main
diaphragm
spring
mounting
Main diaphragm spring
after wear
as new
Adjusting ring with ramps
Compression spring
Gearbox
In the S4, power is transmitted through the
already familiar 6-speed Quattro manual
gearbox of type 01E (C90 gearbox).
As is normal with Audi’s high-performance
models, the gearbox oil is cooled by an oil
pump and an oil cooler.
Oil pump
Due to the two mass flywheel in
combination with the SAC clutch, a
new 11 mm-thick spacer ring is used
for the manual gearboxes in
between the engine and gearbox.
SSP 198/76
The
Audi A6
combined with the following gearbox versions
at the customer’s option:
with biturbo engine can be
Front-wheel drive Manual gearbox 01E (without oil cooling)
Quattro drive Manual gearbox 01E (without oil cooling
Front-wheel drive Automatic gearbox 01V
Quattro drive Automatic gearbox 01V
to oil cooler
71
Notes
72
Dear reader,
With its innovative development of the new biturbo engine, AUDI has
achieved a further milestone in the field of engineering.
With this Self-study Programme you were able to familiarise yourself with
the technology of the biturbo.
In the course of work on our corporate identity (CI), the Self-study
Programme now has a new format. For example, the SSP number is
printed on the back page of the booklet so that you no longer need to take
the booklet out of the folder when searching for it.
Please fax us your suggestions for improving the Self-study Programmes
on +49 841-89-6367.
With the kind regards of your Technical Service Training Team
73
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