air filter JAGUAR XJ6 1997 2.G Owner's Manual

of these sensors and their corresponding
ECU-controlled relays are not contained
within EFI components, but are located
throughout the engine compartment. For
further information regarding the ECU and its
relationship to the engine electrical and
ignition system, see Chapter 6.
12 Electronic Fuel Injection
(EFI) system- check
2
1Check the earth wire connections for
tightness. Check all wiring and electrical
connectors that are related to the system.
Loose electrical connectors and poor grounds
can cause many problems that resemble
more serious malfunctions.
2Check to see that the battery is fully
charged, as the control unit and sensors
depend on an accurate supply voltage in
order to properly meter the fuel.
3Check the air filter element - a dirty or
partially blocked filter will severely impede
performance and economy (see Chapter 1).
4If a blown fuse is found, renew it and see if
it blows again. If it does, search for a shorted
wire in the harness related to the system.
5Check the air intake duct from the MAF
sensor to the intake manifold for leaks, which
will result in an excessively lean mixture. Also
check the condition of the vacuum hoses
connected to the intake manifold.
6Remove the air intake duct from the throttle
body and check for carbon and residue build-
up. If it’s dirty, clean with aerosol carburettor
cleaner (make sure the can says it’s safe for
use with oxygen sensors and catalytic
converters) and a toothbrush.
7With the engine running, place a
stethoscope against each injector, one at a
time, and listen for a clicking sound, indicating
operation (see illustration).8If there is a problem with an injector,
purchase a special injector test light (noid
light) and refit it into the injector electrical
connector (see illustration). Start the engine
and make sure that each injector connector
flashes the noid light. This will test for the
proper voltage signal to the injector.Caution:
If the engine will not start and the noid
light indicates that each injector is
receiving the proper signal, there is a good
possibility that the injector(s) is stuck open
and allowing fuel into the combustion
chamber in excessive amounts. If the spark
plugs are fouled, detach the primary (low
voltage) wires from the ignition coil, disable
the fuel pump by removing the fuel pump
relay (see Section 2), remove the spark plugs
and crank the engine over. If fuel sprays from
the spark plug holes, the engine is flooded
and the fuel must be removed from the
combustion chambers.
9With the engine OFF and the fuel injector
electrical connectors disconnected, measure
the resistance of each injector (see
illustration). Each injector should measure
about 2.0 to 3.0 ohms. If not, the injector is
probably faulty.10The remainder of the system checks
should be left to a Jaguar service department
or other qualified repair workshop, as there is
a chance that the control unit may be
damaged if not performed properly.
13 Electronic Fuel Injection
(EFI) system- component
check and renewal
3
Warning: Petrol is extremely
flammable, so take extra
precautions when you work on
any part of the fuel system. See
the Warning in Section 2.
Caution: If the stereo in your vehicle is
equipped with an anti-theft system, make
sure you have the correct activation code
before disconnecting the battery.
Throttle body
Check
1Verify that the throttle linkage operates
smoothly.
2Start the engine, detach each vacuum hose
and, using your finger, check the vacuum at
each port on the throttle body with the engine
at idle and above idle. The vacuum available
from the throttle body is ported. Raise the
engine rpm and watch as vacuum increases.
It may be necessary to use a vacuum gauge.
Refer to Chapter 2B for additional information
concerning vacuum checks.
Renewal
Warning: Wait until the engine is
completely cool before
beginning this procedure.
3Detach the cable from the negative terminal
of the battery (see the Cautionat the
beginning of this Section).
4Drain the radiator (see Chapter 1).
4•10 Fuel and exhaust systems
12.9 Using an ohmmeter, measure the
resistance across both terminals
of the injector
3261 Jaguar XJ6 12.7 Use a stethoscope or a screwdriver to determine if the
injectors are working properly - they should make a steady
clicking sound that rises and falls with engine speed changes
12.8 Refit the “noid” light into the fuel injector electrical
connector and check to see that it blinks with the engine running

canister. If fuel is leaking, renew the canister
and check the hoses and hose routing.
9Inspect the canister. If it’s cracked or
damaged, renew it.
10Check for a clogged filter or a damaged
pressure relief valve. Using low pressure
compressed air (such as from a tyre pump),
blow into the canister tank pipe. Air should
flow freely from the other pipes. If a problem is
found, renew the canister.
11Check the operation of the thermal
vacuum valve (TVV). With the engine cold and
idling, check for ported vacuum to the
temperature vacuum switch. Vacuum should
be present (see illustration). Now warm the
engine to operating temperature (above
115°F/43°C) and confirm that ported vacuum
passes through the TVV (see illustration).
Renew the valve if the test results are
incorrect.
12Check the operation of the purge control
valve. Apply vacuum to the purge control valve
using a hand-held vacuum pump and observe
that the valve holds vacuum steadily (see
illustration). If the valve holds vacuum and the
valve is opening, it is working properly.
Charcoal canister renewal
13Clearly label, then detach the vacuum
hoses from the canister.
14Remove the mounting clamp bolts (see
illustration), lower the canister with thebracket, disconnect the hoses from the check
valve and remove it from the vehicle.
15Refitting is the reverse of removal.
8 Crankcase ventilation
system
General information
1The crankcase ventilation system reduces
hydrocarbon emissions by scavenging
crankcase vapours. It does this by circulating
fresh air from the air cleaner through the
crankcase, where it mixes with blow-by gases
and is then re-routed through a heating
element to the intake manifold(see
illustration).
2The main components of the crankcase
ventilation system are the control orifice, a
heating element and the vacuum hoses
connecting these components with the engine.
3Piston blow-by gasses are collected from
the crankcase and the camshaft housing
via the oil filler tube. These gasses are fed into
the intake manifold at part throttle through the
part throttle orifice and when the engine is at
full throttle, the gasses are fed through the air
intake elbow.
4To prevent possible icing-up during cold
weather operation, the control orifice and the
hose to the intake system is electronically
heated. The heater element is energised by a
relay signal from the windscreen washer jet
temperature sensor.
Check
5Remove the tubes and elbows that connect
the crankcase ventilation system and inspect
them for obstructions, oil deposits or clogging.
Make sure the ventilation system is free of all
Emissions and engine control systems 6•11
6
7.11a Check for vacuum to the thermal
vacuum valve (TVV)7.11b Check for vacuum from the TVV
before and after the engine has reached
normal operating temperature
7.12 Remove the front spoiler to gain
access to the purge control valve (see
Chapter 11). Apply vacuum to the valve and
make sure the valve holds vacuum7.14 Remove the bolts (arrowed) and lower
the charcoal canister from the wing
8.1 Schematic of the crankcase ventilation system
3261 Jaguar XJ6

Test the brakes at various speeds with both
light and heavy pedal pressure. The vehicle
should stop evenly without pulling to one side
or the other. Avoid locking the brakes,
because this slides the tyres and diminishes
braking efficiency and control of the vehicle.
Tyres, vehicle load and wheel alignment are
factors which also affect braking performance.
2 Anti-lock Brake system
(ABS)- general information
The Anti-lock Brake System is designed to
maintain vehicle steerability, directional stability
and optimum deceleration under severe
braking conditions on most road surfaces. It
does so by monitoring the rotational speed of
each wheel and controlling the brake line
pressure to each wheel during braking. This
prevents the wheels from locking up.
The ABS system has three main units - the
wheel speed sensors, the electronic control unit
and the modulator (hydraulic control unit). The
sensors - one at each wheel - send a variable
voltage signal to the electronic control unit,
which monitors these signals, compares them
to its program and determines whether a wheel
is about to lock up. When a wheel is about to
lock up, the control unit signals the hydraulic
unit to reduce hydraulic pressure (or not
increase it further) at that wheel’s brake caliper.
Pressure modulation is handled by three
electrically-operated solenoid valves - one for
each front wheel and one for the rear wheels -
inside the modulator.
If a problem develops within the system, an
“ABS” warning light will glow on the dashboard.
Sometimes, a visual inspection of the ABS
system can help you locate the problem.
Carefully inspect the ABS wiring harness. Pay
particularly close attention to the harness and
connections near each wheel. Look for signs of
chafing and other damage caused by
incorrectly routed wires. If a wheel sensor
harness is damaged, the sensor should be
replaced (the harness and sensor are integral).
Warning: Do NOT try to repair an
ABS wiring harness. The ABS
system is sensitive to even thesmallest changes in resistance. Repairing
the harness could alter resistance values
and cause the system to malfunction. If the
ABS wiring harness is damaged in any way,
it must be replaced.
Caution: Make sure the ignition is turned
off before unplugging or reattaching any
electrical connections.
Diagnosis and repair
If a dashboard warning light comes on and
stays on while the vehicle is in operation, the
ABS system requires attention. Although
special electronic ABS diagnostic testing tools
are necessary to properly diagnose the system,
you can perform a few preliminary checks
before taking the vehicle to a dealer service
department or other qualified repair workshop.
a) Check the brake fluid level in the master
cylinder reservoir.
b) Verify that all ABS system electrical
connectors in the engine compartment
are plugged in.
c) Check the fuses.
d) Follow the wiring harness to each front
wheel and to the differential sensor and
verify that all connections are secure and
that the wiring is undamaged.
If the above preliminary checks do not
rectify the problem, the vehicle should be
diagnosed by a dealer service department.
Due to the complex nature of this system, all
actual repair work must be done by a dealer
service department or other qualified repair
workshop.
3 Disc brake pads- renewal
2
Warning: Disc brake pads must
be replaced on both front wheels
or both rear wheels at the same
time - never renew the pads on
only one wheel. Also, the dust created by
the brake system may contain asbestos,
which is harmful to your health. Never blow
it out with compressed air and don’t inhale
any of it. An approved filtering mask should
be worn when working on the brakes. Do
not, under any circumstances, use
petroleum-based solvents to clean brake
parts. Use brake system cleaner only!
Note:The following procedure applies to both
the front and rear brake pads.
1Remove the cap from the brake fluid
reservoir and siphon off about two-thirds of
the fluid from the reservoir. Failing to do this
could result in fluid overflowing when the
caliper pistons are pressed into their bores.
2Loosen the wheel nuts, raise the front of the
vehicle and support it securely on axle stands.
3Remove the front wheels. Work on one
brake assembly at a time, using the
assembled brake for reference if necessary.
4Inspect the brake disc (see Section 5).
5Follow the accompanying photos,
beginning with illustration 3.5a, for the pad
removal procedure. Be sure to stay in order
and read the caption under each illustration.
9•2 Braking system
3.5a Before starting, wash down the
caliper and disc with brake cleaner
3.5b Attach a hose to the bleed screw,
open the bleed screw slightly and depress
the piston into the caliper. Tighten the
bleed screw when the piston bottoms
3.5c Remove the caliper mounting bolts
(upper bolt arrowed); use another spanner
to hold the flats of the caliper guide pins
while you back out the caliper bolts3.5d Remove the caliper . . .3.5e . . . and suspend it out of the way
with a piece of wire
3261 Jaguar XJ6

6Be sure to buy new pads with wear
sensors. Pattern pads may not have wear
sensors; refitting pads without wear sensors
will cause the dash warning light to come on.
7To refit the new pads, reverse the removal
procedure. When refitting the caliper, be sure
to tighten the mounting bolts to the torque
listed in this Chapter’s Specifications.
8After the job is completed, depress the
brake pedal a few times to bring the pads into
contact with the discs. The pedal should be at
normal height above the floorpan and firm.
Check the brake fluid level and add enough to
top it up (see Chapter 1). Inspect carefully for
leaks and check the operation of the brakes
before placing the vehicle into normal service.
9Tighten the wheel nuts to the specified
torque.
4 Disc brake caliper- removal,
overhaul and refitting
3
Warning: Dust created by the
brake system may contain
asbestos, which is harmful to
your health. Never blow it out
with compressed air and don’t inhale any
of it. An approved filtering mask should be
worn when working on the brakes. Do not,
under any circumstances, use petroleum-
based solvents to clean brake parts. Use
brake system cleaner only!
Note 1:The following procedure applies to
both front and rear calipers.
Note 2:If an overhaul is indicated, explore all
options before beginning the job. New andfactory rebuilt calipers are available on an
exchange basis, which makes this job quite
easy. If you decide to rebuild the calipers,
make sure a rebuild kit is available before
proceeding. Always rebuild the calipers in
pairs - never rebuild just one of them.
Removal
1Loosen the wheel nuts, raise the front or
rear of the vehicle and place it securely on
axle stands. Remove the wheel.
2If you’re just removing the caliper for
access to other components, it isn’t
Braking system 9•3
9
3.5f Remove the outer brake pad3.5g Remove the inner brake pad
3.5h Pull out the wear sensor, trace the
sensor lead back to its plug, detach the
lead from the suspension, and discard it
3.5i Remove the caliper guide pins and
boots (lower pin and boot shown) . . .
3.5j . . . clean them off, inspect the pin and
boot for damage, renew as necessary,
then lubricate the pins with brake grease
and refit them in the caliper bracket
3.5k Apply anti-squeal compound to the
new brake pads
3261 Jaguar XJ6
3.5l Insert the new wear sensor into the
inner pad as shown . . .
3.5n Refit the outer pad
3.5m . . . then refit the inner pad onto the
caliper bracket
3.5o Refit the caliper, then tighten the
mounting bolts to the specified torque

11 Handbrake cable(s)- renewal
2
1Raise the vehicle and place it securely on
axle stands.
Front cable
2Remove the cotter pin, washer and clevis
pin from the forward end of the front cable
(see illustration). Disconnect the forward end
of the front cable from the handbrake lever.
3Follow the cable back to the adjuster lever
and remove the cotter, washer and clevis pin
(see illustration). Remove the front cable.
4Refitting is the reverse of removal.
Intermediate cable
5Remove the cotter pins, washers and clevis
pin from both ends of the intermediate cable
(see illustration). Remove the cable.
6Refitting is the reverse of removal.
Rear cables
7Remove the cotter pin, washer and clevis
pin from the intermediate cable-to-rear cable
yoke (see illustration).
8Disconnect the rear end of each cable from
the handbrake assembly (see illustration).,
then pry the cable out of the carrier.
9Refitting is the reverse of removal.
All cables
10Be sure to adjust the handbrake cable
when you’re done (see Section 10). The rear
wheels should turn freely with the handbrake
lever released.
11Remove the axle stands and lower the
vehicle. Apply the handbrake lever, make sure
it’s fully applied within three to five clicks and
that it holds the vehicle on an incline. If it
doesn’t, readjust it (see Section 10).
12 Handbrake shoes-
check and renewal
2
Warning: Dust created by the
brake system may contain
asbestos, which is harmful to
your health. Never blow it out
with compressed air and don’t inhale any
of it. An approved filtering mask should be
worn when working on the brakes. Do not,
under any circumstances, use petroleum-
based solvents to clean brake parts. Use
brake system cleaner only!
Check
1The handbrake system should be checked
regularly. With the car parked on a hill, apply
the brake, place the transmission in Neutral
and check that the handbrake alone will hold
the car (be sure to stay in the car during this
check). However, every 24 months (or
Braking system 9•11
9
3261 Jaguar XJ6 11.2 To disconnect the forward end of the
front cable from the handbrake lever,
remove this cotter pin, washer
and clevis pin
11.3 To disconnect the rear end of the
front cable from the adjuster lever, remove
this cotter pin, washer and clevis pin
(arrowed)11.5 To disconnect the intermediate cable,
remove the cotter pins, washers and clevis
pins (arrowed) from the adjuster lever
and the yoke
11.7 To disconnect the rear cables and yoke from the
intermediate cable, remove this cotter pin, washer
and clevis pin (arrowed)11.8 The rear handbrake cable-to-handbrake shoe connection is
hidden behind the lower part of the brake backing plate, on the
underside of the carrier (this view is looking straight up from
underneath the carrier). To disconnect either rear handbrake
cable, swing this clip (arrowed) to the side and remove it - the
rear cable is now disconnected

3261 Jaguar XJ6
REF•4Buying spare parts
Spare parts are available from many
sources, including maker’s appointed
garages, accessory shops, and motor factors.
To be sure of obtaining the correct parts, it
will sometimes be necessary to quote the
vehicle identification number. If possible, it
can also be useful to take the old parts along
for positive identification. Items such as
starter motors and alternators may be
available under a service exchange scheme -
any parts returned should be clean.
Our advice regarding spare parts is as
follows.
Officially appointed garages
This is the best source of parts which are
peculiar to your car, and which are not
otherwise generally available (eg, badges,
interior trim, certain body panels, etc). It is
also the only place at which you should buy
parts if the vehicle is still under warranty.
Accessory shops
These are very good places to buy
materials and components needed for themaintenance of your car (oil, air and fuel
filters, light bulbs, drivebelts, greases, brake
pads, touch-up paint, etc). Components of
this nature sold by a reputable shop are
usually of the same standard as those used
by the car manufacturer.
Besides components, these shops also sell
tools and general accessories, usually have
convenient opening hours, charge lower
prices, and can often be found close to home.
Some accessory shops have parts counters
where components needed for almost any
repair job can be purchased or ordered.
Motor factors
Good factors will stock all the more
important components which wear out
comparatively quickly, and can sometimes
supply individual components needed for the
overhaul of a larger assembly (eg, brake seals
and hydraulic parts, bearing shells, pistons,
valves). They may also handle work such as
cylinder block reboring, crankshaft regrinding,
etc.
Tyre and exhaust specialists
These outlets may be independent, or
members of a local or national chain. They
frequently offer competitive prices when
compared with a main dealer or local garage,
but it will pay to obtain several quotes before
making a decision. When researching prices,
also ask what “extras” may be added - for
instance fitting a new valve and balancing the
wheel are both commonly charged on top of
the price of a new tyre.
Other sources
Beware of parts or materials obtained from
market stalls, car boot sales or similar outlets.
Such items are not invariably sub-standard,
but there is little chance of compensation if
they do prove unsatisfactory. In the case of
safety-critical components such as brake
pads, there is the risk of financial loss, and
also of an accident causing injury or death.
Second-hand parts or assemblies obtained
from a car breaker can be a good buy in some
circumstances, but this sort of purchase is
best made by the experienced DIY mechanic.
Vehicle identification
Modifications are a continuing and
unpublicised process in vehicle manufacture,
quite apart from major model changes. Spare
parts manuals and lists are compiled upon a
numerical basis, the individual vehicle
identification numbers being essential to
correct identification of the part concerned.
When ordering spare parts, always give as
much information as possible. Quote the car
model, year of manufacture and registration,
chassis and engine numbers as appropriate.
The Vehicle Identification Number (VIN)
plate is attached to the base of the driver’s
door pillar left-hand wing valance and is
visible once the bonnet has been opened. The
vehicle identification (chassis) number is also
stamped onto a plate located inside the
windscreen and may also be stamped onto
the right-hand inner wing panel in the engine
compartment (see illustrations).
The trim code and paint codeare also
stamped onto the VIN plate.
The engine numberis stamped onto the
right-hand side of the cylinder block, next to
the distributor (see illustration).
The automatic transmission numberis
stamped onto a metal label attached to the
left-hand side of the transmission housing,
just above the sump (see illustration).The VIN is stamped on the right inner wing
panel of the engine compartment
The engine identification number is
stamped on the right side of the engine
block just behind the distributorThe transmission identification number is
located on the left side of the transmission
housing just above the sump
The VIN is also present on the left side of
the dashboard

3261 Jaguar XJ6
REF•6Tools and working facilities
Introduction
A selection of good tools is a fundamental
requirement for anyone contemplating the
maintenance and repair of a motor vehicle.
For the owner who does not possess any,
their purchase will prove a considerable
expense, offsetting some of the savings made
by doing-it-yourself. However, provided that
the tools purchased meet the relevant national
safety standards and are of good quality, they
will last for many years and prove an
extremely worthwhile investment.
To help the average owner to decide which
tools are needed to carry out the various tasks
detailed in this manual, we have compiled
three lists of tools under the following
headings: Maintenance and minor repair,
Repair and overhaul, and Special. Newcomers
to practical mechanics should start off with
the Maintenance and minor repairtool kit, and
confine themselves to the simpler jobs around
the vehicle. Then, as confidence and
experience grow, more difficult tasks can be
undertaken, with extra tools being purchased
as, and when, they are needed. In this way, a
Maintenance and minor repairtool kit can be
built up into a Repair and overhaultool kit over
a considerable period of time, without any
major cash outlays. The experienced do-it-
yourselfer will have a tool kit good enough for
most repair and overhaul procedures, and will
add tools from the Specialcategory when it is
felt that the expense is justified by the amount
of use to which these tools will be put.
Maintenance
and minor repair tool kit
The tools given in this list should be
considered as a minimum requirement if
routine maintenance, servicing and minor
repair operations are to be undertaken. We
recommend the purchase of combination
spanners (ring one end, open-ended the
other); although more expensive than open-
ended ones, they do give the advantages of
both types of spanner.
MCombination spanners:
Metric - 8 to 19 mm inclusive
MAdjustable spanner - 35 mm jaw (approx.)
MSpark plug spanner (with rubber insert) -
petrol models
MSpark plug gap adjustment tool - petrol
models
MSet of feeler blades
MBrake bleed nipple spanner
MScrewdrivers:
Flat blade - 100 mm long x 6 mm dia
Cross blade - 100 mm long x 6 mm dia
MCombination pliers
MHacksaw (junior)
MTyre pump
MTyre pressure gauge
MOil can
MOil filter removal tool
MFine emery cloth
MWire brush (small)
MFunnel (medium size)
Repair and overhaul tool kit
These tools are virtually essential for
anyone undertaking any major repairs to a
motor vehicle, and are additional to those
given in the Maintenance and minor repairlist.
Included in this list is a comprehensive set of
sockets. Although these are expensive, they
will be found invaluable as they are so
versatile - particularly if various drives are
included in the set. We recommend the half-
inch square-drive type, as this can be used
with most proprietary torque wrenches.
The tools in this list will sometimes need to
be supplemented by tools from the Speciallist:
MSockets (or box spanners) to cover range in
previous list (including Torx sockets)
MReversible ratchet drive (for use with
sockets)
MExtension piece, 250 mm (for use with
sockets)
MUniversal joint (for use with sockets)
MTorque wrench (for use with sockets)
MSelf-locking grips
MBall pein hammer
MSoft-faced mallet (plastic/aluminium or
rubber)
MScrewdrivers:
Flat blade - long & sturdy, short (chubby),
and narrow (electrician’s) types
Cross blade – Long & sturdy, and short
(chubby) types
MPliers:
Long-nosed
Side cutters (electrician’s)
Circlip (internal and external)
MCold chisel - 25 mm
MScriber
MScraper
MCentre-punch
MPin punch
MHacksaw
MBrake hose clamp
MBrake/clutch bleeding kit
MSelection of twist drills
MSteel rule/straight-edge
MAllen keys (inc. splined/Torx type)
MSelection of files
MWire brush
MAxle stands
MJack (strong trolley or hydraulic type)
MLight with extension lead
Sockets and reversible ratchet drive
Clutch plate alignment setPiston ring compressorSpline bit set
Valve spring compressor

3261 Jaguar XJ6
MOT test checksREF•11
MExamine the handbrake mechanism,
checking for frayed or broken cables,
excessive corrosion, or wear or insecurity of
the linkage. Check that the mechanism works
on each relevant wheel, and releases fully,
without binding.
MIt is not possible to test brake efficiency
without special equipment, but a road test can
be carried out later to check that the vehicle
pulls up in a straight line.
Fuel and exhaust systems
MInspect the fuel tank (including the filler
cap), fuel pipes, hoses and unions. All
components must be secure and free from
leaks.
MExamine the exhaust system over its entire
length, checking for any damaged, broken or
missing mountings, security of the retaining
clamps and rust or corrosion.
Wheels and tyres
MExamine the sidewalls and tread area of
each tyre in turn. Check for cuts, tears, lumps,
bulges, separation of the tread, and exposure
of the ply or cord due to wear or damage.
Check that the tyre bead is correctly seated
on the wheel rim, that the valve is sound andproperly seated, and that the wheel is not
distorted or damaged.
MCheck that the tyres are of the correct size
for the vehicle, that they are of the same size
and type on each axle, and that the pressures
are correct.
MCheck the tyre tread depth. The legal
minimum at the time of writing is 1.6 mm over
at least three-quarters of the tread width.
Abnormal tread wear may indicate incorrect
front wheel alignment.
Body corrosion
MCheck the condition of the entire vehicle
structure for signs of corrosion in load-bearing
areas. (These include chassis box sections,
side sills, cross-members, pillars, and all
suspension, steering, braking system and
seat belt mountings and anchorages.) Any
corrosion which has seriously reduced the
thickness of a load-bearing area is likely to
cause the vehicle to fail. In this case
professional repairs are likely to be needed.
MDamage or corrosion which causes sharp
or otherwise dangerous edges to be exposed
will also cause the vehicle to fail.
Petrol models
MHave the engine at normal operating
temperature, and make sure that it is in good
tune (ignition system in good order, air filter
element clean, etc).
MBefore any measurements are carried out,
raise the engine speed to around 2500 rpm,
and hold it at this speed for 20 seconds. Allowthe engine speed to return to idle, and watch
for smoke emissions from the exhaust
tailpipe. If the idle speed is obviously much
too high, or if dense blue or clearly-visible
black smoke comes from the tailpipe for more
than 5 seconds, the vehicle will fail. As a rule
of thumb, blue smoke signifies oil being burnt
(engine wear) while black smoke signifies
unburnt fuel (dirty air cleaner element, or other
carburettor or fuel system fault).
MAn exhaust gas analyser capable of
measuring carbon monoxide (CO) and
hydrocarbons (HC) is now needed. If such an
instrument cannot be hired or borrowed, a
local garage may agree to perform the check
for a small fee.
CO emissions (mixture)
MAt the time of writing, the maximum CO
level at idle is 3.5% for vehicles first used after
August 1986 and 4.5% for older vehicles.
From January 1996 a much tighter limit
(around 0.5%) applies to catalyst-equipped
vehicles first used from August 1992. If the
CO level cannot be reduced far enough to
pass the test (and the fuel and ignition
systems are otherwise in good condition) then
the carburettor is badly worn, or there is some
problem in the fuel injection system or
catalytic converter (as applicable).
HC emissionsMWith the CO emissions within limits, HC
emissions must be no more than 1200 ppm
(parts per million). If the vehicle fails this test
at idle, it can be re-tested at around 2000 rpm;
if the HC level is then 1200 ppm or less, this
counts as a pass.
MExcessive HC emissions can be caused by
oil being burnt, but they are more likely to be
due to unburnt fuel.
Diesel models
MThe only emission test applicable to Diesel
engines is the measuring of exhaust smoke
density. The test involves accelerating the
engine several times to its maximum
unloaded speed.
Note: It is of the utmost importance that the
engine timing belt is in good condition before
the test is carried out.
M
Excessive smoke can be caused by a dirty
air cleaner element. Otherwise, professional
advice may be needed to find the cause.
4Checks carried out on
YOUR VEHICLE’S EXHAUST
EMISSION SYSTEM

3261 Jaguar XJ6
Fault findingREF•13
1 Engine
Engine will not rotate when attempting to start
m mBattery terminal connections loose or corroded (Chapter 1).
m mBattery discharged or faulty (Chapter 1).
m mDamaged left rear window harness shorting against glass rail
inside door, causing battery to drain (Chapter 12).
m mAutomatic transmission not completely engaged in Park
(Chapter 7).
m mBroken, loose or disconnected wiring in the starting circuit
(Chapters 5 and 12).
m mStarter motor pinion jammed in flywheel ring gear (Chapter 5).
m mStarter solenoid faulty (Chapter 5).
m mStarter motor faulty (Chapter 5).
m mIgnition switch faulty (Chapter 12).
m mStarter pinion or flywheel teeth worn or broken (Chapter 5).
m mInternal engine problem (Chapter 2B).
m mInertia switch activated (Chapter 12).
m mStarter relay defective (Chapter 5).
Engine rotates but will not start
m
mFuel tank empty.
m mBattery discharged (engine rotates slowly) (Chapter 5).
m mBattery terminal connections loose or corroded (Chapter 1).
m mLeaking fuel injector(s), faulty fuel pump, pressure regulator, etc.
(Chapter 4).
m mFuel not reaching fuel injection system (Chapter 4).
m mIgnition components damp or damaged (Chapter 5).
m mFuel injector stuck open (Chapter 4).
m mWorn, faulty or incorrectly gapped spark plugs (Chapter 1).
m mBroken, loose or disconnected wiring in the starting circuit
(Chapter 5).
m mLoose distributor is changing ignition timing (Chapter 1).
m mBroken, loose or disconnected wires at the ignition coil or faulty
coil (Chapter 5).
m m1988 and 1989 models may have electrical connector damage
between the fuel pump relay and the fuel pump (Chapter 12).
m mCoolant temperature sensor shorting on bonnet liner (Chapter 11).
m mDefective Mass Airflow (MAF) sensor (Chapter 6).
Engine hard to start when cold
m
mBattery discharged or low (Chapter 1).
m mFuel system malfunctioning (Chapter 4).
m mInjector(s) leaking (Chapter 4).
m mDistributor rotor carbon tracked (Chapter 5).
m mWater enters the air cleaner housing near the left front wheel arch
(Chapter 4).
Engine hard to start when hot
m mAir filter clogged (Chapter 1).
m mFuel not reaching the fuel injection system (Chapter 4).
m mCorroded battery connections, especially ground (Chapter 1).
m mFuel vaporises at fuel pump inlet. Refit dual fuel pumps
(Chapter 4).
m mFuel vapours from charcoal canister enter intake during idle and
cause idling, stalling and starting problems (Chapter 6).
Starter motor noisy or excessively rough in
engagement
m mPinion or flywheel gear teeth worn or broken (Chapter 5).
m mStarter motor mounting bolts loose or missing (Chapter 5).
Engine starts but stops immediately
m
mLoose or faulty electrical connections at distributor, coil or
alternator (Chapter 5).
m mInsufficient fuel reaching the fuel injector(s) (Chapters 1 and 4).
m mDamaged fuel injection system speed sensors (Chapter 5).
m mFaulty fuel injection relays (Chapter 5).
m mLeaking threaded adapter on the EGR valve - where fitted
(Chapter 6)
Oil puddle under engine
m mSump gasket and/or sump drain bolt seal leaking (Chapter 2).
m mOil pressure sending unit leaking (Chapter 2).
m mValve cover gaskets leaking (Chapter 2).
m mEngine oil seals leaking (Chapter 2).
m mCylinder head rear plate gasket leaking (Chapter 2).
m mAlternator mounting bolt threads leaking oil (Chapter 5).
m mOil cooler or oil cooler lines leaking (Chapter 3).
Engine misses while idling or idles erratically
m
mVacuum leakage (Chapter 2).
m mAir filter clogged (Chapter 1).
m mFuel pump not delivering sufficient fuel to the fuel injection system
(Chapter 4).
m mLeaking head gasket (Chapter 2).
m mTiming belt/chain and/or sprockets worn (Chapter 2).
m mCamshaft lobes worn (Chapter 2).
m mEGR valve stuck open - where fitted (Chapter 6).
Engine misses at idle speed
m
mSpark plugs worn or not gapped properly (Chapter 1).
m mFaulty spark plug leads (Chapter 1).
m mVacuum leaks (Chapter 1).
m mIncorrect ignition timing (Chapter 5).
m mUneven or low compression (Chapter 2).
m mRestricted EGR vacuum hose - where fitted (Chapter 6).
Engine misses throughout driving speed range
m
mFuel filter clogged and/or impurities in the fuel system (Chapter 1).
m mLow fuel output at the injectors (Chapter 4).
m mFaulty or incorrectly gapped spark plugs (Chapter 1).
m mIncorrect ignition timing (Chapter 5).
m mCracked distributor cap, disconnected distributor wires or
damaged distributor components (Chapter 1).
m mLeaking spark plug leads (Chapter 1).
m mFaulty emission system components (Chapter 6).
m mLow or uneven cylinder compression pressures (Chapter 2).
m mWeak or faulty ignition system (Chapter 5).
m mVacuum leak in fuel injection system, intake manifold or vacuum
hoses (Chapter 4).
m mCrankshaft sensor teeth damaged or missing (see Chapter 12).
m mDistributor installed incorrectly (see Chapter 5)
Engine stumbles on acceleration
m
mSpark plugs fouled (Chapter 1).
m mFuel injection system malfunctioning (Chapter 4).
m mFuel filter clogged (Chapters 1 and 4).
m mIncorrect ignition timing (Chapter 5).
m mIntake manifold air leak (Chapter 4).
m mCollapsed or damaged fuel tank caused by blocked EVAP system
- where fitted (see Chapter 6).

3261 Jaguar XJ6
REF•14Fault finding
2 Fuel system
Engine surges while holding accelerator steady
m mIntake air leak (Chapter 4).
m mFuel pump faulty (Chapter 4).
m mLoose fuel injector harness connections (Chapters 4 and 6).
m mDefective ECU (Chapter 6).
Pinking or knocking engine sounds during
acceleration or uphill
m mIncorrect grade of fuel.
m mDistributor installed incorrectly (Chapter 5).
m mFuel injection system in need of adjustment (Chapter 4).
m mImproper or damaged spark plugs or wires (Chapter 1).
m mWorn or damaged distributor components (Chapter 5).
m mFaulty emission system (Chapter 6).
m mVacuum leak (Chapter 4).
m mFuel rail feed (inlet) hose has hardened, resulting in knocking noise
near dash (see Chapter 4).
Engine lacks power
m mIncorrect ignition timing (Chapter 5).
m mExcessive play in distributor shaft (Chapter 5).
m mWorn rotor, distributor cap or wires (Chapters 1 and 5).
m mFaulty or incorrectly gapped spark plugs (Chapter 1).
m mFuel injection system malfunctioning (Chapter 4).
m mFaulty coil (Chapter 5).
m mBrakes binding (Chapter 1).
m mAutomatic transmission fluid level incorrect (Chapter 1).
m mFuel filter clogged and/or impurities in the fuel system (Chapter 1).
m mEmission control system not functioning properly (Chapter 6).
m mLow or uneven cylinder compression pressures (Chapter 2).
Engine rattles at start-up
m
mFailure of upper timing chain tensioner (Chapter 2).
Engine backfires
m
mEmissions system not functioning properly (Chapter 6).
m mIgnition timing incorrect (Chapter 1).
m mFaulty secondary ignition system (cracked spark plug insulator,
faulty plug leads, distributor cap and/or rotor) (Chapters 1 and 5).
m mFuel injection system malfunctioning (Chapter 4).
m mVacuum leak at fuel injector(s), intake manifold or vacuum hoses
(Chapter 4).
Engine stalls
m mIdle speed incorrect (Chapter 1).
m mFuel filter clogged and/or water and impurities in the fuel system
(Chapter 1).
m mDistributor components damp or damaged (Chapter 5).
m mFaulty emissions system components (Chapter 6).
m mFaulty or incorrectly gapped spark plugs (Chapter 1).
m mFaulty spark plug leads (Chapter 1).
m mVacuum leak in the fuel injection system, intake manifold or
vacuum hoses (Chapter 4).
Engine runs with oil pressure light on
m mLow oil level (Chapter 1).
m mIdle rpm too low (Chapter 1).
m mShort in wiring circuit (Chapter 12).
m mFaulty oil pressure sending unit (Chapter 2).
m mWorn engine bearings and/or oil pump (Chapter 2).
Engine diesels (continues to run)
after switching off
m mIdle speed too high (Chapter 4).
m mExcessive engine operating temperature (Chapter 3).
m mIncorrect fuel octane grade.
Excessive fuel consumption
m
mDirty or clogged air filter element (Chapter 1).
m mIncorrectly set ignition timing (Chapter 5).
m mEmissions system not functioning properly (Chapter 6).
m mFuel injection internal parts worn or damaged (Chapter 4).
m mLow tyre pressure or incorrect tyre size (Chapter 1).
Fuel leakage and/or fuel odour
m
mLeak in a fuel feed or vent line (Chapter 4).
m mTank overfilled.
m mFuel injector internal parts excessively worn (Chapter 4).
3 Cooling system
Overheating
m
mInsufficient coolant in system (Chapter 1).
m mWater pump drivebelt defective or out of adjustment (Chapter 1).
m mRadiator core blocked or grille restricted (Chapter 3).
m mThermostat faulty (Chapter 3).
m mRadiator cap not maintaining proper pressure (Chapter 3).
m mIgnition timing incorrect (Chapter 5).
Overcooling
m
mFaulty thermostat (Chapter 3).
External coolant leakage
m
mDeteriorated/damaged hoses; loose clamps (Chapters 1 and 3).
m mWater pump seal defective (Chapters 1 and 3).
m mLeakage from radiator core or manifold tank (Chapter 3).
m mEngine drain or water jacket core plugs leaking (Chapter 2).
m mHoses behind water pump leaking (Chapter 3).
Internal coolant leakage
m
mLeaking cylinder head gasket (Chapter 2).
m mCracked cylinder bore or cylinder head (Chapter 2).
Coolant loss
m
mToo much coolant in system (Chapter 1).
m mCoolant boiling away because of overheating (Chapter 3).
m mInternal or external leakage (Chapter 3).
m mFaulty radiator cap (Chapter 3).
Poor coolant circulation
m
mInoperative water pump (Chapter 3).
m mRestriction in cooling system (Chapters 1 and 3).
m mWater pump drivebelt defective/out of adjustment (Chapter 1).
m mThermostat sticking (Chapter 3).
1 Engine (continued)