1999 JAGUAR S TYPE engine

V8 EngineAJ-V6/AJ28
57
Air Assisted Injection
The air assisted injection system is very similar to
the AJ27 system, with a solenoid valve controlling
an air supply to the fuel injector nozzles. The AJ28
engine uses a different type of injector and air
assist control AAC valve. The AAC valve bolts to
the side of the throttle adaptor which provides an
inlet port connection from the intake resonator
duct via a hose and an outlet port to the air rails.
The injectors are located in the air rails which are
integral with the manifold.
J.303.1257
AAC VALVE AND AIR DISTRIBUTION
J.303.1257
J.303.1392
AAC VALVE
J.303-1392
Valve shown in the closed,
de-energised state
InletOutlet
AAC Valve

V8 Engine AJ-V6/AJ28
58FUEL INJECTOR
303-135
Fuel Injectors
The type of fuel injector used operates in a similar
way to the type fitted to the AJ27 engine but has a
different shroud arrangement at the nozzle to
provide the air/fuel mixing.
Fuel Supply
Assisted
Air Inlet

V8 EngineAJ-V6/AJ28
59
Front End Accessories Drive
The front end accessories drive has a modified
belt run, new type ancillaries and modified
mounting brackets. The belt is changed to a
6-ribbed type and all pulleys are changed to suit.
Idler Pulleys and Tensioner
Two idler pulleys are used, the lower one
mounted on the generator bracket and a new idler
which screws directly into the engine front cover.
The tensioner is mounted on the PAS pump
support bracket.
Generator
The generator is electrically identical to the unit
fitted to the V6 engine but with a different outer
casing which allows it to be mounted via a similar
(not identical) bracket to the AJ27 unit.
J.303.1394
J.303.1394
PAS Pump
Generator ENGINE ACCESSORIES AND DRIVE BELT
Coolant Pump
A/C Compressor
Drive Belt
Tensioner Crankshaft
Damper Pulley Idler pulley
Idler pulley

V8 Engine AJ-V6/AJ28
60A/C Compressor
A new type A/C compressor is fitted. The unit is
attached via an upper mounting bracket to the
block and directly to the bedplate by lower bolts.PAS Pump
A new type of PAS pump/pulley assembly and
mounting bracket are fitted.
D.303.1264
D.303.1265
PAS PUMP
303-091
A/C COMPRESSOR
303-091

Automatic TransmissionAJ-V6/AJ28
61
Introduction
The 5R55N type 5-speed automatic transmission is fitted to both the V6 and V8 engines. The
transmission is controlled electronically by the powertrain control module (PCM) without the use of a
dedicated control module. Normal P, R, N, D drive functions plus manual selection of 4th, 3th and 2nd
gears are provided by a Jaguar style ÔJÕ gate (not the same as XJ and XK Series - see ÔS-TYPE IntroductionÕ
Techical Guide). Sports mode and traction assistance are selected at the ÔJÕ gate.
Specification
Transmission weight with fluid: 90 kg (198 lbs)
Oil type: Mercon V semi-synthetic (not compatible with other fluids)
Oil capacity: 9 Litres (9.5 quarts) - new
5 Litres (5.3 quarts) - after draining
Oil Fill/change: Filled for life, no top up required (no dipstick)
Gear ratios: 1st 2nd 3rd 4th 5th Rev
3.24 : 1 2.44 : 1 1.55 : 1 1 : 1 0.75 : 1 3.07 : 1
D.307.313
5R55N AUTOMATIC TRANSMISSION
D.303.313
Vent Tube
Turbine Speed
Sensor
Intermediate
Speed Sensor
Output Speed
Sensor
Range Switch
Rear Mounting
BracketJ-gate Selector
Cable Lever

Automatic Transmission AJ-V6/AJ28
62
D.307.321
V8 Engine Adaptor Plate
D.307.321
1. J-gate selector cable lever
2. Range switch
3. Control Module
4. Solenoid block assembly5. Filter assembly
6. Sump
7. Drain plug
Construction and Operation
The transmission housing consists of a one piece
die cast aluminium case with re-inforcement ribs
to minimise noise, vibration, and harshness
(NVH). To allow for the different physical size of
the engines, there are two transmission variants
with different overall lengths and bell housings to
match the respective engines, the V8 variant being
shorter. Different torque converters are necessary
and the V8 variant is also fitted with an adaptorplate to mate the torque converter to the larger
diameter drive plate on the V8 engine.
The main features of the transmission unit are :
¥ torque converter with a twin friction face
lock-up clutch and torsional damper
¥ geartrain consisting of three epicyclic gearsets
¥ shift elements consisting of multi-plate
clutches, brakes and one way clutches
¥ control actuators: four shift solenoids, three
variable force solenoids and a PWM 5R55N AUTOMATIC TRANSMISSION
1
3
7
6
5
24

Automatic TransmissionAJ-V6/AJ28
63 controlled solenoid are mounted on an
integral, replaceable, control module
¥ three speed sensors mounted on the external
casing: turbine speed sensor, intermediate
speed sensor and output speed sensor
¥ an oil temperature sensor is fitted inside the
transmission.
The gear select lever is connected via a Bowden
cable to an operating lever on the left side of the
transmission casing. A digital rotary switch, the
transmission range switch, fits over the shaft of
the operating lever and is fixed by two bolts to
the transmission casing. Selection of a particular
drive function generates a 4 bit binary coded
signal which is transmitted directly to the PCM
over a four wire parallel interface. As on the XK
and XJ Series, lateral movement of the gear select
lever across the gate, D to 4 or 4 to D, operates a
switch which indicates the selected function to
the PCM (the Bowden cable is not actuated
laterally).
The PCM directly controls the transmission
actuators as a response to driver demand, engine
requirements and according to the selected shift
mode. Gear selection is controlled by commands
to the four shift solenoids. If, during gear
selection, the relative speeds monitored by the
speed sensors are not as expected, the PCM
varies the analogue signal to the variable force
solenoids to increase/decrease the clutch pressure
(closed loop control). Increased engagement times
due to ageing are also controlled by adaptive shiftpressure.
Apart from the sports mode and traction mode
selected by the driver, there are pre-programmed
modes selected by the PCM in response to sensed
driving conditions :
¥ increased load such as gradients and trailer
towing
¥ cruise control
¥ hot mode: strategies including clutch lock up
are applied to reduce heat.
Transmission Oil Cooler
The transmission fluid is cooled externally by a
dedicated oil to air radiator which is mounted in
the integral cooling pack between the engine
radiator and A/C condenser and below the PAS
cooler.
D.307.320
TRANSMISSION OIL COOLING
Transmission
Oil Cooler
D.307.320

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