1998 JAGUAR X308 engine ignition

IGNITION.
All circuits, except the star
ter motor, are activated. The key rema ins in this position when driving.
Position 'III'

START. The starter operates for as long as the key is held in this position, ag ainst spring pressure. If the engine fails to
start, the key must be returned to position 'I' befo re another start is attempted.
Lighting Switch

The li
ghting switch is on the left-h
and side of the steering column and controls the following functions.
Direction Indicators

The direction in
dicators:
Operate
when the ignition switch is in position II.
Are operat
ed by movi
ng the switch stalk up or down until it latches in position, to in
dicate a right or left turn
respectively.
Can be o p
erated while the switch stalk is held against
spring pressure before reaching the latch position.
Cancel
automatically upon completion of a turn, the
column switch returning to the center position.
An audible ticking and a flashing green warning lamp on the in strument cluster indicate that the direction indicators are
Ite
m
De
scr
iption
1D
i
rection indicator LH or RH position
2All lamps OFF
3Side
lamps ON
4Headlamps ON
5Headlamps AUT O
(where fitted)
6He
adlam
p main beam position
7Mai
n
beam flash position
8M
e
ssage center function button

diverter val
ve (if fitted) and oil filter.
Main
bearings
which are grooved in the upper positions and plain in
the lower positions. They are manufactured from
aluminium / tin material.
A c
rankshaft with under
cuts and rolled fillets for extra strength.
Fracture
-split connecting rods in sintered-forged steel.
Brackets
bolted to the front of
the cylinder
block are used to mo unt all accessories.
A sin
gle, seven ribbed vee belt
drives the accessories.
An au
tomatic belt tensioner for the front accessory drive,
incorporating a wear indicator.
An advanced en
gine management system inco
rporating electronic throttle control.
The un
it meets the requirements of the CARB OBDII USA legislation.
Ancillary Systems
The an
ci
llary systems, driven by the engine, each have a
detailed Description and Operation along with Diagnostic
Procedures, and Removal and Installation instructions ; refer to the following sections of this manual:
Power Steeri
ng Pump - Section 211-02
Ai
r Conditioning Compressor - Sectio
n 412-03
Engine
C
ooling Pump - Section 303-03
Generator
- Sectio
n 414-02
The drive belt, idler pulley and automatic tensioner are described in Section 303-05.
The engine starting system is described in Section 303-06.
En
gine Management and Emission Control System
Engine Control Modu
le (ECM)
Engine
management and exhaust emissions are controlled by the ECM, which has the
following main functions:
Fu
el injection
Idle
s
peed
Ignition Ev

aporative loss system
Engine
cooling fans Clim
ate control compressor clutch demand
The microprocessor within the ECM receiv es signals from various sensors and other modules and uses a pre-determined
program to compute engine management functions.
Adaptive functions are incorporated in the ECM to cater for co ntinuous adjustments to its computations to suit prevailing
conditions. Because the system also controls emissions to suit all modes, neither CO levels nor idle speed require service
attention or adjustment, except if an error should occur.
On Board Diagnostics are controlled by the ECM with the continuous monitoring of incoming signals and the subsequent
verification against what the module expects to 'see'. Should a si gnal be incorrect or missing, the ECM will substitute a fixed
value to provide the 'limp home mode' and alert the driver of the problem. Fixed values may be adopted for:
Transmission oil
temperature
Mechanica
l
guar
d position
Throttle blade angle Camshaft position

Inta
k
e air temperature
Diagnostic trouble codes (DTC), including OBD II codes, are stored in the ECM memo ry and can be read by an appropriate
retrieval tool.
Should either the ECM or TCM fa il, ensure that the control housing cooling fan is operating correctly. Failure of the cooling
fan MUST be rectified before renewing a control module and details of a fa n failure should accompany a returned control
module.

2—Ignition ampl
ifier failure
3—Crankin

g
4—Camshaft position


5—Mass ai

r flow
6—Inta

ke air temperature
7—Coo

lant temperature
8—Exhaus

t gas oxygen content
9—Knock

sensor

10—Power supply
11—Cl
imate control compressor
12—Cli

mate control system pressure
13—Traction contr

ol
14—Park / neutral

switch
15—Throttle pedal demand


16—Thro

ttle position
17—Securi

ty mode



ECM In
puts
It

em
Par
t Number
De
scription
1—Engine

speed

E
ngine Management System Components
Electronic Throt
tle
The
electronic throttle assembly, in resp
onse to signals from both the driver and the ECM, adjusts idle speed, sets the
throttle valve to the position requested by the driver's accelerator / throttle pedal, cruise and traction control, power
limitation and catalyst warm-up.
Mass
Air Flow Meter
The sensor i
s located in the air flow mete
r assembly and outputs an analogue voltag e to the ECM. This sensor measures air
flow into the engine inlet system and is calibrated to measure kg / hour.
In
take Air Temperature
Th
e intake air temperature sensor is loca
ted in the air flow meter assembly and outputs an analogue voltage to the ECM.
The ECM will substitute a default value eq ual to 50°C should this sensor fail.
Fuel Injectors
The eigh
t bottom fed fuel injectors are located in the fuel rails. Th
e fuel injectors are electromagnetic solenoid valves
controlled by the ECM. The pulse time for the injector combined with the fuel pr essure determines the volume of fuel
injected to the manifold.
Fue
l Delivery
The fu
el pump provides fuel to the fuel rail where the circulat
ing pressure is controlled by a pressure regulator valve; excess
fuel is returned to the fuel tank.
The pressure regulator valve is controlled by manifold depression so that fuel delivery pressure is maintained at
approximately 3 bar above manifold pressure.
Fuel Pump
Relay
The ECM controls thi

s component for normal
engine running. The security system may disable this relay via communication
with the ECM.
Fuel Lev
el Sensing
The tank fuel

is measured by the fuel le
vel sensor . This signal is used by the ECM as an in put to certain diagnostics.
Eva
porative Valve
Excess vapour

formed in the fuel tank is
absorbed into the evaporative emission pu rge control canister. While the engine is
running, the fuel absorbed in the canister is gradually purged back into the engine. The rate of purging is governed by
engine operating conditions and vapour concentration level. Operating conditions which affect the purge rate are:
2—Purge
valve
3—Engine

torque reduction
4—E

lectronic throttle assembly
5—Coo

ling fans
6—Ignition amplifier driver
7—Engine overspeed
8—Cli

mate control compressor clutch
9—O

BDII information (J1962, CAN, ISO)

10—F
uel pump relay
11—Heat

ed oxygen sensor
12—Vari

able valve timing
13—MIL sw

itching



ECM Out
puts
It

em
Par
t Number
De
scription
1—Exhaus

t gas recirculation

Speed an
d load
Coo
l
ant temperature
Ti
me el
apsed from start up
Cl
osed l
oop fuelling
Determination of the vapour concentration is made by stepped opening of the EVAP valve and subsequent monitoring of the
fuelling correction. This function is performed prior to purging, so that at the onse t of purging the EVAP valve can be set to
the optimum position. Should the ECM be unable to determine the concentration before purging, a default value is
employed, which is then modified whilst purging is in progress.
When the purging process is operational th e ECM modifies the basic fuelling calculation to maintain the correct air / fuel
ratio.
Purging is inhibited during fuel cut-off and stability / traction control intervention.
Coolant Temperature Sen
sor
Th
e
sensor outputs a voltage to the ECM which decreases as temperature increases.
Cooling Fans


In response to engi
ne coolant temperat
u
re and climate control system demand, the ECM will energize the cooling fans.
Climate Control Compressor
The E
C
M will allow the compressor clutch to be engaged if th
e engine temperature and load demand are normal. Should the
driver require maximum engine powe r or the coolant temperature be high, the request will be denied.
Cranking Signal

The ECM reacts to a signal fr
om th
e Body Processor Module (BPM) when the starter motor relay is energi
zed. This signal is
used to trigger starting, fu el and ignition strategies.
Engine Speed and Cranksh
aft Position
Engine
speed and cran
k position are moni
tored by a sensor which is mounted on the cylinder block (flywheel housing)
behind the crankshaft drive plat e. It indicates rotational speed to the ECM in the form of 12 pulses per crank revolution.
Engine speed is used for synchronization of fuel an d ignition systems, as well as other functions.
Camshaft Position
The ca
mshaft position sensor is mounted at
the rear of Bank 2 cylinder head on the inlet side and provides one signal every
720 degrees of crankshaft rotation. The signal, in conjunction with the signal from the crankshaft position sensor, indicates
to the ECM that the piston of cylinder 1A is approaching TDC on the compression stroke.
Variable Valve
Timing (Where Fitted)
By energi
si
ng a solenoid to allow the pass
age of pressurized oil on each of the inle t camshaft drives, the ECM can vary by a
single stepped amount, the relati ve timing of the inlet valves.
Ign
ition
Ignit
i
on spark is produced by
individual on-plug coil units.
There are two ignition amplifiers; module #1 drives coils 1A, 2B, 3B and 4A, whilst module #2 drives coils 1B, 2A, 3A and
4B. The ECM controls the amplifiers.

Thi
s sensor uses a piezo-electric sensing element to detect kn
ock which may occur under acceleration at critical conditions.
Should detonation be present the ECM will retard ignition timing of individual cylinders.
Exhaust G
as Recirculation
The EGR
valve (where fitted) reduces NOx
emissions by recirculating a portion of the exhaust gases back into the inlet
manifold.
Heated Oxyg
en Sensors
The h
eated oxygen sensors, one per bank, are situated upstream of the catalysts. Integral
to the sensors are heaters
(under ECM control) which allow the sensor s to reach their operating temperature as soon as possible after engine start. A
comparison between the level of oxygen in the exhaust gas to that in the atmosphere produces an output signal. This signal
is used by the engine closed loop fuel strategy to make fuelling corrections and so control overall emission levels.
Oxygen Sensors

Thes
e sensors, one per bank, are situated downstream of the
catalyst. The comparison of upstream and downstream signals
allows determination of cata lyst conversion efficiency.




Knock Sensor

En
gine - Valve Clea
rance Adjustment
Gene
ral Procedures
S
p
ecial Tool(s)

Tappet adjustment
3
03-
540

Ai
r gun, fan nozzl
e
303-590
1. Open the engine compartment and fit paintwork protection
sheets. Open to the service position.
2. Carefully remove both engine covers, taking care not to
damage the plasti c fixings or the rubber inserts.

3. Disc
onnect the batt
ery ground cable.
Re
move the battery cover.
4. Remove the cam cover from the 'A' bank and the 'B' bank;
including the purge valve, the on-plug ignition coils and the air
intake tube / air flow meter / air cleaner cover assembly. Refer
to Operations 12.29.43 and 12.29.44.
5. Check, and note the valve cleara nces, as described earlier in
this section.
6. Use a rag to wipe up as much oil as possible from the tappet
wells.
7. Valve adjustment involves considerable repetition. A SUMMARY
OF THE PROCEDURE follows:
1. Fit the adjusting tool base plate to one cylinder head.
2. Rotate the crankshaft to position four valves ready for
adjustment.
3. Use the attachment part of the special tool to adjust two valve clearances. Transfer the attachment and
adjust the other two valve clearances.
4. Remove the attachment pa rt from the adjusting tool
base plate.

E
ngine - Valve Clearance Check
Gen
eral Procedures

1.
Open the engine compartment and fit paintwork protection
sheets. Open to the service position.
2. Carefully remove both engine covers, taking care not to
damage the plasti c fixings or the rubber inserts.

3. Di
sconnect the batt
ery ground cable.
R
emove the battery cover.
4. Remove the cam cover from the 'A' bank and the 'B' bank;
including the purge valve, the on-plug ignition coils and the air
intake tube / air flow meter / air cleaner cover assembly. Refer
to Operations 12.29.43 and 12.29.44.
5. Rotate the crankshaft so that there are four valves which are
'off the cam' (cam lobes upperm ost), so that their clearance
may be measured.
6. Measure the gap on each of the four valves. Note which valve
has been measured, along with its relevant clearance.
7. Rotate the crankshaft a small am ount so that the next four
valves are 'off the cam'. Measure and note the clearances.
Re
peat this step
a further six times, until all valve
clearances have been measured and noted.
8. Refit the cam covers and associated components. Refer to
Operations 12.29.43 and 12.29.44.
9. Refit the engine covers.
10. Move the engine compartment cover from the service position
and connect the gas struts.
11. Remove the paint protection sheets and close the cover.
12. Connect the battery and fit the battery cover.
Re
fer to the Battery Reconnection Procedure 86.15.15