1998 AUDI S4 clutch

3
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.
Page
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
4
Motronic ME 7.1 ..........................................
Subfunctions, system overview
31
Subsystems of the Motronic .....................
Torque-oriented engine management, torque-
oriented functional structure, Electronic throttle,
exhaust gas temperature control
33
Sensors .......................................................
Additional sensors of the Motronic
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
64
Transmission ..............................................
Self-adjusting clutch, gearbox
66
Contents
Important!/Note!
New!

19
Rear view of engine
SSP 198/52

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)
Lambda probe
G108
Exhaust gas temperature
sender G236 (with
evaluation electronics)Lambda probe G39
SAC clutch pressure plate
Prim. catal. converterPrim. catal. converter

32
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

Sensors
Engine speed sender G28
Hall senders (bank 2) G40 and (bank 1)
G163
Lambda probes (bank 1) G39 and (bank 2) G108
Throttle valve control part J338
with angle sender (1) G187 and (2) G188 for
throttle valve drive G186
Intake air temperature sender G42
Coolant temperature senders G2 and G62
Charge pressure sender G31
Knock sensors (bank 1) G61 and (bank 2) G66Accelerator position sender G79 and 2 G185Exhaust gas temperature senders (bank 1)
G235 and (bank 2) G236Brake light switch F and brake pedal
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
Motronic ME 7.1

56
Sensors
Brake light switch F and brake
pedal switch F47The 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.
Clutch pedal switch F36 ...
Wrong settings, electrical malfunctions or maloperation (driver keeps foot on clutch
pedal) may result in load change jolts or engine speed overshoots.
... 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.
SSP 198/63
Brake light switch F and
brake pedal switch F47
Clutch pedal switch F36

62
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
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 5N189 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
Colour codes:
Input signal
Output signal
Positive
Earth
Bidirectional

66
Power Transmission
Self-adjusting clutch
Advantages:
• Constant clutch releasing loads throughout
the service life of the clutch plate.
• Greater wear reserve of the clutch plate. For the biturbo engines, Audi is
using an SAC clutch pressure plate
with a wear compensation feature
for the first time.
„
SAC
“ stands for
S
elf-
A
djusting
C
lutch.
SSP 198/42

Auxiliary spring
Adjusting ringSensor plate spring
Main diaphragm spring
Compression spring
Housing cover

67
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.
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).

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.
SSP 198/41

Housing cover
SSP 198/72
0 -1 -2 1 2 3 4

Pressure plate travel in mm
Contact pressure
Fitting location
Wear reserve

Contact pressure characteristic
(conventional clutch )
Sensor plate spring
Main diaphragm spring
Adjusting ring
Auxiliary spring
Disengaging stop

68
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)The
stop for release travel
limits the
travel of the release bearing and
prevents unintentional adjustment of
the adjusting ring.
The
auxiliary spring
counteracts the
main plate spring as of a defined
travel distance and ensures an even
force curve during clutch engagement
and disengagement.
SSP 198/70

Housing cover with auxiliary spring
and s
top for release travel
Main diaphragm spring
Pressure plate
Auxiliary spring
(riveted on)
Sensor plate spring
Adjusting ring with
compression springs