Jaguar AJV8 engine / 5HP24 transmission. Manual - part 7

Engine

AJ-V8/5HP24

Springs

The input shaft spring and the mechanical guard
spring oppose movement in the throttle open
direction, and provide the "feel" of the accelerator
pedal. The throttle valve spring and the drive gear
spring oppose movement in the throttle closed
direction.

Operation

The design of the input shaft and the mechanical
guard, and the bias of their respective springs,
means that, except in cruise control, they always
rotate together. The throttle cable turns them in
the open direction; the springs keep their
adjacent levers locked together and turn them in
the closed direction.
The ECM monitors the position of the input shaft
and mechanical guard using the inputs from the
accelerator pedal and mechanical guard position
sensors. During normal operation, when the ECM
detects any movement it signals the dc motor to

turn the throttle valve and follow the input shaft
and mechanical guard, maintaining a constant
gap between the adjacent levers of the throttle
valve and mechanical guard. The dc motor drive
gears turn the throttle valve in the closed
direction; the throttle valve spring turns the
throttle valve in the open direction and keeps the
throttle valve in contact with the drive gear.
Inputs from the throttle valve position sensor
enable the ECM to exercise closed loop control.
The arrangement of the throttle valve drive
prevents the ECM from exceeding driver
demand, since if the motor is driven fully open
the throttle valve engages the mechanical guard
and disengages from the dc motor drive gears.
The arrangement of the mechanical guard to
throttle valve interface allows the ECM to reduce
throttle opening to less than driver demand, eg.
during stability/traction control or engine power
limiting.

ELECTRONIC THROTTLE

Coolant
Inlet

Thermostatic
Air Valve

dc Motor

Coolant
Outlet

Vent

Vacuum Actuator

303-067

Engine

AJ-V8/5HP24

Operating Modes (Refer to the figure, page 31)

Normal

1. Throttle cable inputs driver demand
2. Input shaft turns mechanical guard
3. Sensors supply ECM with inputs of driver demand
4. ECM operates dc motor
5. Sensor supplies ECM with inputs of throttle valve position
6. Gap maintained between throttle valve and mechanical guard

Cruise Control

1. Vacuum actuator turns mechanical guard
2. Sensor supplies ECM with mechanical guard position
3. ECM operates dc motor
4. Sensor supplies ECM with inputs of throttle valve position
5. Gap maintained between throttle valve and mechanical guard
6. Input shaft at idle position, disengaged from mechanical guard

Mechanical Guard

1. Throttle cable inputs driver demand
2. Input shaft turns mechanical guard
3. Mechanical guard turns throttle valve
4. dc motor drive disengaged from throttle valve

At idle, the ECM controls engine speed using the
restricted throttle valve movement available
between the mechanical guard (open limit) and a
factory set stop on the dc motor drive gear
(closed limit).
When cruise control is engaged, the ECM
calculates the required throttle valve opening and
operates the vacuum system connected to the
vacuum actuator. The vacuum actuator then turns
the mechanical guard to a position that allows the
required throttle valve opening. The inputs from
their respective position sensors allow the ECM
to monitor and adjust the mechanical guard and
the throttle valve to maintain the set speed. As
the driver releases the accelerator pedal, the
input shaft disengages from the mechanical
guard. Note that during cruise control, when

accelerating above the set speed, the accelerator
pedal has a lighter "feel" until the input shaft
engages with the mechanical guard again.
Mechanical operation of the throttle valve occurs
if the ECM selects the mechanical guard mode of
operation after detecting a fault. The ECM de-
energizes the dc motor and the throttle valve
spring turns the throttle valve in the open
direction until it engages the mechanical guard.
The input shaft, mechanical guard and throttle
valve are then effectively locked together by their
springs, so that the throttle cable is in direct
control of the throttle valve. When the throttle
valve opens, it turns the dc motor drive gears. On
subsequent closing of the throttle valve the drive
gears remain in the open position, disengaged
from the throttle valve.

Engine

AJ-V8/5HP24

ELECTRONIC THROTTLE OPERATING MODES

Normal

Mechanical Guard

Cruise Crontrol

Spring Force

303-080,/081/082

Engine

AJ-V8/5HP24

Induction Elbow

The induction elbow provides the interface
between the electronic throttle and the intake
manifold. Connections on the induction elbow
provide vacuum take-offs for various services. A
boss on the rear of the elbow accommodates the
EGR valve.

Intake Manifold

The intake manifold is manufactured in
composite, with integrated composite fuel rails
and metal thread inserts. Individual ducts lead off
a central chamber to the inlet ports of each
cylinder.
Silicon rubber gaskets, located in channels in the
intake manifold, seal the joints between the ducts
and the cylinder heads.

Fuel Tank Vacuum
and Pressure Relief
Valve Connection

Part Load Breather/
EVAP Valve Vacuum
Connection

Brake Booster
Vacuum Connection

Fuel Pressure
Regulator/
Cruise Control
Vacuum
Connection

303-033

INDUCTION ELBOW

SECTION THROUGH INTAKE MANIFOLD

303-051

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