1999 JAGUAR S TYPE Powertrain Manual

V8 Engine AJ-V6/AJ28
52
J.303.1251
D.303.1268 & J.303.1251
D.303.1268
INDUCTION MANIFOLD AND THROTTLE ADAPTOR
Vacuum Connections
AAC Valve Inlet
Noise Isolation Pad
AAI Supply
Tube
Evaporative
Emissions Inlet
AAC Valve
Outlet
AAC Valve
Coolant PipesPart Load
Breather Inlet

V8 EngineAJ-V6/AJ28
53
J.303.1359
INDUCTION VACUUM AND AIR SUPPLY CONNECTIONS
J.303.1359
Induction and Vacuum System
Emission and vacuum connections to the
induction system are shown in the illustration
above.Variable Valve Timing (VVT)
The inlet valve timing gear is fitted with the same
continuously VVT system as is used on the AJ27
engine. Operation is as described in the ÔXJ and
XK Series 1999MY UpdateÕ Technical Guide, with
the following variations:
¥ engine management system
¥ PWM solenoid control frequency is 300Hz
¥ the use of five toothed sensor rings for cam
position feedback
Note that the use of this VVT system eliminates
the need for external EGR components.
AAI Valve Inlet
Brake Servo
Vacuum
EVAP Emissions
EVAP Valve
Vacuum Control
Part Load
Breather
IP Sensor
Vacuum
Full Load
Breather

V8 Engine AJ-V6/AJ28
54
Engine Management Sensors
The configuration of the AJ28 engine management sensors is changed from the previous V8 variants:
¥ New components unique to AJ28 engine are the MAF sensor and engine fuel temperature (EFT)
sensor.
¥ Components in common with the V6 engine are the IAT sensor, KS sensors, injector pressure (IP)
sensor, engine oil temperature (EOT) sensor and HO2 sensors.
¥ The crankshaft (CKP) and camshaft (CMP) sensors are the same as those fitted to the AJ27 engine.
Heated Oxygen (HO2) Sensors
Upstream and dowmstream HO2 sensors are
fitted and are of the type used on the V6 engine
(the linear type sensor is not used).
J.303.1387
HO2 SENSORS
J.303.1387
J.303.1281
COIL ON PLUG UNIT
J.303.1281
Ignition System
The coil-on-plug ignition modules are specific to
the AJ28 engine and are triggered directly from
the PCM. Double electrode platinum plugs are
fitted.

V8 EngineAJ-V6/AJ28
55
J.303.1389
ENGINE MANAGEMENT SCHEMATIC
13
2
45
6
8
157
9
1110
13
16
J.303-1287
9
10
12
14
Key :
1. MAF sensor
2. IAT sensor
3. TP sensor
4. Throttle motor
5. AAC valve
6. IP sensor8
11
16
1616
7. EFT sensor
8. Fuel injectors
9. CMP sensor
10. Coil-on-plug units
11. VVT shuttle valve
12. ECT sensor13. KS sensors
14. CKP sensor
15. EOT sensor
16. HO2 sensors

V8 Engine AJ-V6/AJ28
56
Fuel Injection
Returnless Fuel System
The function and operation of the returnless fuel
system is the same as that fitted to the V6 engine
but with different fuel pipework to suit the V8
layout. The air assisted, top fed, fuel injectors are
supplied from two separate rails joined by an
interconnecting cross-over pipe (similar to AJ27)
with a single common feed from the fuel tank.
The fuel rail assembly is removeable. An engine
fuel temperature (EFT) sensor and injector
pressure (IP) sensor provide feedback to the PCM
to control the fuel pump flow rate (see ÔS-TYPE
IntroductionÕ Technical Guide). Note that the EFT
sensor is not in direct contact with the fuel (ÔdryÕ
type sonser).
J.303.1390
FUEL RAIL ASSEMBLY
IP Sensor
EFT Sensor
J.303.1390

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