service JAGUAR S TYPE 1999 1.G Powertrain Manual

Published by Service Communications, J Ja
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Publication Part No JJM 10 15 17/92, February 1999

Published by Service Communications, J Ja
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gu
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Ca
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Publication Part No JJM 10 15 17/92, February 1999
Technical Guide
Jaguar S-TYPE
Sports Sedan
Powertrain
Introduction

Preface AJ-V6/AJ28
This Technical Guide introduces the engines and transmissions for the new S-TYPE sports sedan.
It is intended to give Jaguar Dealer workshop personnel an overview of their construction and operation,
and is for information purposes only.
The contents of this Technical Guide must not be used as a reference source for servicing procedures; all
servicing must be carried out in accordance with the appropriate JTIS disc.
This Technical Guide will not be updated. While every effort is made to ensure accuracy, changes may
occur between going to press and the equipment being introduced to the market. Once the equipment is
in service, details of changes can be obtained from Service Bulletins and revisions to the JTIS disc.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or
transmitted, in any form, electronic, mechanical, photocopying, recording or other means without prior
written permission from the Service Division of Jaguar Cars Limited.

V6 Engine
6
Basic Engine
Engine Structure
Basic engine construction is similar to the V8 in
that a structural bedplate is used which bolts to
the cylinder block to provide a very strong
housing for the crankshaft, minimising vibration.
Both units are of cast aluminium alloy and are
accurately aligned together by the use of eight
hollow dowels.
The cylinder block is fitted with dry cast iron
liners.
The oil sump is an aluminium alloy casting which
combines a sump body and oil pan in a single
structural component. The sump mounts to the
bedplate via an aluminium gasket incorporating a
silicone rubber seal.
D.303.1360
D.303.1360
ENGINE STRUCTURE
D.303.1364
ENGINE DATA LOCATIONS
Engine Identification Data
An engine identification code tag is located on the
bank 2 side of the front cover assembly.
Mains bearing selection codes are located at the
rear of the cylinder block and on the rear face of
the crankshaft flange. The two codes are
compared using reference data provided in the
JTIS service information to identify the correct
bearing.
Engine identification codeMains bearing selection codes
D.303.1364
AJ-V6/AJ28

V6 Engine AJ-V6/AJ28
26
J.303.1316
J.303.1362
THROTTLE BODY ASSEMBLY
TP/APP SENSORS - GENERAL CHARACTERISTICStwo fixed external connectors. The TAC module is
mounted on the underside of the throttle body
and drive motor unit with its upper connector
plugged directly into a fixed recessed connector
on the drive motor. The front connector provides
the main control interface with the PCM. Note
that the motor unit and the TAC module are
electronically calibrated together on initial
manufacture (the TAC module ÔlearnsÕ the motor
characteristics) and must not be individually
replaced. The throttle assembly as a whole is not
a serviceable item except for the TP sensor.
Two stub pipes at the rear of the throttle body are
connected via hoses into the engine cooling
system to provide throttle de-icing.
Throttle Position (TP) Sensor
The TP sensor is bolted to the non drive end of
the throttle body and is rotated directly (1:1) by
the blade ended throttle shaft. It has three non-
contacting, Hall effect, sensing elements which
are supplied from the PCM by two separate 5V
reference and signal return lines. Each sensor
provides an independent analogue output to the
PCM. For additional security, each sensor element
has a unique rotational angle to output voltage
characteristic (see Figure); the three outputs are
compared by the PCM for the expected values for
a particular throttle angle. This arrangement
identifies a sensor or wiring fault including a short
circuit between outputs.
Output Voltage
Sensor Rotor AngleDegrees
V
TAC Module
J.303.1382 J.303.1316
TP Sensor
Drive Motor
Sensor 3 Sensor 2Sensor 1
Throttle Body

V6 EngineAJ-V6/AJ28
43 Intake Air Temperature (IAT) Sensor
The IAT sensor is a conventional thermistor type
device which is a push fit in the intake resonator
duct.
Mass Air Flow (MAF) Sensor
The MAF sensor is an integral assembly consisting
of a hot wire sensor unit and air duct and is non-
serviceable. The assembly is fitted between the air
cleaner and intake resonator tube.
D.303.1381
MAF AND IAT SENSORS
D.303-1381
J.303.1386
HO2 SENSORS
J.303-1386
Heated Oxygen (HO2) Sensors
HO2 sensors are fitted in both the upstream and
downstream positions on the catalytic converters.
Both sensors are standard types with a step
response at the stoichiometric (lambda) air/fuel
value. The upstream sensors provide the feedback
for stoichiometric fuelling control and the
downstream sensors monitor catalyst efficiency
and also provide long term fuelling adaptation
trim.
MAF SensorIAT Sensor

Manual TransmissionAJ-V6/AJ28
65
D.307.315
Gear Selector Control
The gear selector mechanism is designed to give a
smooth positive action. The lever assembly is
mounted via a bracket to the floor, not the
transmission. Further isolation is provided by the
use of low friction bushes and tuned shift
mechanism compliance.
Flywheel and Clutch
The clutch system is based on the established
principle of a single driven plate and diaphragm
spring hydraulically actuated from the clutch pedal
but incorporates the following special features:
¥ dual mass flywheel
¥ self adjusting clutch
¥ concentric slave cylinder.
Flywheel
While the use of a dual mass flywheel is not new
to Jaguar, the model described here incorporates
the latest refinements in the technology. Relative
rotational movement between the primary and
secondary flywheel masses via the damper system
is greater than on previous vehicles, giving further
improvements in torsional vibration isolation
(engine irregularities) and reducing stresses on the
crankshaft and drivetrain. Steel pressings rather
than castings are used to reduce the weight of the
assembly. The flywheel assembly is not a
serviceable item but the bearing can be released
for servicing.
Self Adjusting Clutch
The self adjusting clutch is an innovative feature
which improves operation and driver comfort by
enabling a constant pedal pressure to be applied
as the friction faces wear, unlike conventional
types of clutch which require increasing pressure
with wear. GEARSHIFT CONTROL LINKAGE
D.303.315

Manual Transmission AJ-V6/AJ28
66With a conventional clutch, increased lining wear
causes the angle of the actuating diaphragm
spring to change as the pressure plate moves
axially towards the engine, requiring a greater
force to operate the clutch (diaphragm actuating
force varies with diaphragm angle). The self
adjusting clutch eliminates the problem by
allowing the diaphragm spring to follow the axial
movement of the pressure plate thus maintaining
the diaphragm spring at the same angle
throughout the life of the clutch. As well as
maintaining a constant pedal pressure, the clamp
force on the pressure plate also remains constant
with wear.
The operation is shown in the diagram. The
diaphragm spring is not fixed at its rotation point
like the conventional system but pivots between a
sensor spring and an adjuster ring. The sensor
spring provides a counter force which is just
sufficient to retain the diaphragm spring axially
against the cover via the adjuster ring and during
normal actuation of the clutch. As the linings
wear, the tendency of the diaphragm angle to
change causes an increase in the actuation force
required to operate the clutch. When this
increased effort exceeds the counter force of the
sensor spring, the diaphragm spring moves axially
towards the pressure plate until the original angle
is restored. At this point the actuation force
required drops to the level of the opposing sensor
spring force, restoring equilibrium with the
diaphragm spring at its new location.
During the axial movement of the diaphragm
spring, the increased distance between the spring
and cover is taken up by the adjuster ring. This
ring has fifteen raised segments, each having a
ramp profile which fits into a corresponding
shape in the clutch cover. When the diaphragm
spring moves axially for wear compensation,
three pre-loaded coil springs in the clutch cover
cause the adjuster ring to rotate, moving up the
ramps and taking up the extra distance between
the diaphragm spring and clutch cover.
Note that, in operation, the adjuster ring rotates
in a clockwise direction, as viewed from the
transmission. If a worn driven plate is replaced in
service and the clutch cover assembly is to be re-
used, the adjuster ring must be rotated back to its
pre-loaded position (see JTIS service instructions).
J.307.318
DUAL MASS FLYWHEEL AND CLUTCH ASSEMBLY
J.307.318
J.307.319
OPERATION OF SELF ADJUSTING CLUTCH
J.307.319
Dual Mass
Flywheel
Assembly
Self Adjusting
Clutch
Driven Plate
Concentric
Slave Cylinder
Adjuster
Ring
Conventional
Clutch
Sensor Spring
Diaphragm
Spring
Self Adjusting
Clutch
Diaphragm
Spring