V8 EngineAJ-V6/AJ28
51
Air Induction System
Charge air is supplied to the cylinders via an air
cleaner, induction tube, throttle body, throttle
body adaptor and induction manifold.
The throttle body and system operation is
identical to that of the V6 engine.
Induction Manifold
(see illustration on page 52)
To accommodate the V8 engine in the S-TYPE
model, the throttle body is re-located and now
supplies charge air via an inlet at the top centre of
the induction manifold. The manifold is
manufactured from a plastic material and has an
integral injector air supply tube on each side with
holes for the fuel injectors, but as on the AJ27
engine, the fuel feed pipes are not incorporated
into the manifold (see Fuel System). Two stub
pipes at the top of the manifold provide vacuum
connections for the vacuum hose and the brake
servo hose.
A polypropylene covered foam noise isolation pad
fits between the manifold assembly and the block.Throttle Adaptor
The throttle body is mounted to the induction
manifold via a cast aluminium adaptor. The
throttle body adaptor provides input ports for the
evaporative emissions (top stub) and part load
breather (lower side stub) and also mounts the air
assisted injection control (AAC) valve. Input and
output ports for the side mounted AAC valve are
an integral part of the adaptor casting (the ports
do not connect to the induction airstream).
Throttle de-icing is achieved by a coolant feed
through the base of the adaptor instead of the
throttle body itself as on the V6 engine (see
cooling section).
D.303.1278
AIR INDUCTION LAYOUT
D.303.1278
Air Cleaner
Induction Tube
MAF SensorIAT Sensor
Throttle Body
Throttle Body Adaptor
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
