1997 JAGUAR XJ6 Oxygen sensor

5 Air Injector Reactor
(AIR) system
General information
1The air injection reactor system reduces
carbon monoxide and hydrocarbon content
in the exhaust gases by injecting fresh air into
the hot exhaust gases leaving the exhaust
ports. When fresh air is mixed with hot
exhaust gases, oxidation is increased,
reducing the concentration of hydrocarbons
and carbon monoxide and converting them
into harmless carbon dioxide and water.
2The air injection system is composed of an
air pump, diverter valve (bypass), check valve,
air injection manifold, vacuum delay valve,
vacuum control solenoid, air pump magnetic
clutch, air pump clutch relay and hoses (see
illustration). The air pump is driven by a belt
from the crankshaft and supplies compressed
air to the exhaust manifold(s). The check valve
prevents the reverse flow of exhaust gases into
the system. The vacuum-operated (early
models) or electrically-operated (later models)air cut-off valve prevents air from being drawn
into the exhaust when the air pump is switched
off. System vacuum to the air cut-off valve is
controlled by the solenoid vacuum valve in
parallel circuit with the air pump. A delay valve
prevents vacuum loss to the solenoid valve
during wide open throttle operation.
3Injected air is controlled by the computer,
the air pump clutch and the air pump clutch
relay. The AIR system is used during warm-up
(58 to 83° F) to control emissions while the
engine is running rich. The oxygen sensor
feedback system cannot function while the AIR
system is operating. The computer controls
both systems during warm-up and operating
temperatures. If problems occur with the
AIR system relay or circuit, the on-board
diagnosis system will set a code 66.
Check
4Check the condition of the air pump
drivebelt, the injection hoses and the injection
manifold. Make sure that all components are
intact and there are no leaks.
5Check the operation of the air pump clutch
relay (see illustration)and the air pump
clutch. First remove the relay and check forbattery voltage to the relay. Also, check the
relay itself. Refer to the relay checking
procedure in Chapter 12. Extract codes from
the self-diagnosis system (see Section 3) and
check for a code 66, AIR relay malfunction.
6Make sure the electrical connector is
securely fastened to the diverter valve (see
illustration). If everything appears OK but a
fault code still sets, have the system
diagnosed by a dealer service department or
other qualified repair workshop.
Air pump renewal
7Disconnect the cable from the negative
terminal of the battery.
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.
8Disconnect the electrical connector from
the air pump clutch.
9Loosen the clips from the air inlet and outlet
hose and separate them from the air injection
pump.
10Loosen the adjuster and pivot bolts (see
illustration)and nuts but do not remove them
from the air injection pump brackets.
6•8 Emissions and engine control systems
3261 Jaguar XJ6 5.2 Schematic of the Air Injection Reactor (AIR) system
5.6 Location of the AIR diverter valve on a 1992 model - check the
hoses for cracking and the electrical connector for security5.10 Loosen the pivot bolt and then the adjustment nut to remove
the drivebelt from the air pump. The adjustment nut has a lock bolt
that must be loosened before the pump will move down the adjuster
5.5 Location of the AIR pump relay on a 1992 model

3261 Jaguar XJ6
REF•20Glossary of technical terms
GGapThe distance the spark must travel in
jumping from the centre electrode to the side
electrode in a spark plug. Also refers to the
spacing between the points in a contact
breaker assembly in a conventional points-
type ignition, or to the distance between the
reluctor or rotor and the pickup coil in an
electronic ignition.
GasketAny thin, soft material - usually cork,
cardboard, asbestos or soft metal - installed
between two metal surfaces to ensure a good
seal. For instance, the cylinder head gasket
seals the joint between the block and the
cylinder head.
GaugeAn instrument panel display used to
monitor engine conditions. A gauge with a
movable pointer on a dial or a fixed scale is an
analogue gauge. A gauge with a numerical
readout is called a digital gauge.
HHalfshaftA rotating shaft that transmits
power from the final drive unit to a drive
wheel, usually when referring to a live rear
axle.
Harmonic balancerA device designed to
reduce torsion or twisting vibration in the
crankshaft. May be incorporated in the
crankshaft pulley. Also known as a vibration
damper.
HoneAn abrasive tool for correcting small
irregularities or differences in diameter in an
engine cylinder, brake cylinder, etc.
Hydraulic tappetA tappet that utilises
hydraulic pressure from the engine’s
lubrication system to maintain zero clearance
(constant contact with both camshaft and
valve stem). Automatically adjusts to variation
in valve stem length. Hydraulic tappets also
reduce valve noise.
IIgnition timingThe moment at which the
spark plug fires, usually expressed in the
number of crankshaft degrees before the
piston reaches the top of its stroke.
Inlet manifoldA tube or housing with
passages through which flows the air-fuel
mixture (carburettor vehicles and vehicles with
throttle body injection) or air only (port fuel-
injected vehicles) to the port openings in the
cylinder head.
JJump startStarting the engine of a vehicle
with a discharged or weak battery by
attaching jump leads from the weak battery to
a charged or helper battery.
LLoad Sensing Proportioning Valve (LSPV)A
brake hydraulic system control valve that
works like a proportioning valve, but also
takes into consideration the amount of weight
carried by the rear axle.
LocknutA nut used to lock an adjustment
nut, or other threaded component, in place.
For example, a locknut is employed to keep
the adjusting nut on the rocker arm in
position.
LockwasherA form of washer designed to
prevent an attaching nut from working loose.
MMacPherson strutA type of front
suspension system devised by Earle
MacPherson at Ford of England. In its original
form, a simple lateral link with the anti-roll bar
creates the lower control arm. A long strut - an
integral coil spring and shock absorber - is
mounted between the body and the steering
knuckle. Many modern so-called MacPherson
strut systems use a conventional lower A-arm
and don’t rely on the anti-roll bar for location.
MultimeterAn electrical test instrument with
the capability to measure voltage, current and
resistance.
NNOxOxides of Nitrogen. A common toxic
pollutant emitted by petrol and diesel engines
at higher temperatures.
OOhmThe unit of electrical resistance. One
volt applied to a resistance of one ohm will
produce a current of one amp.
OhmmeterAn instrument for measuring
electrical resistance.
O-ringA type of sealing ring made of a
special rubber-like material; in use, the O-ring
is compressed into a groove to provide the
sealing action.
Overhead cam (ohc) engineAn engine with
the camshaft(s) located on top of the cylinder
head(s).Overhead valve (ohv) engineAn engine with
the valves located in the cylinder head, but
with the camshaft located in the engine block.
Oxygen sensorA device installed in the
engine exhaust manifold, which senses the
oxygen content in the exhaust and converts
this information into an electric current. Also
called a Lambda sensor.
PPhillips screwA type of screw head having a
cross instead of a slot for a corresponding
type of screwdriver.
PlastigageA thin strip of plastic thread,
available in different sizes, used for measuring
clearances. For example, a strip of Plastigage
is laid across a bearing journal. The parts are
assembled and dismantled; the width of the
crushed strip indicates the clearance between
journal and bearing.
Propeller shaftThe long hollow tube with
universal joints at both ends that carries
power from the transmission to the differential
on front-engined rear wheel drive vehicles.
Proportioning valveA hydraulic control
valve which limits the amount of pressure to
the rear brakes during panic stops to prevent
wheel lock-up.
RRack-and-pinion steeringA steering system
with a pinion gear on the end of the steering
shaft that mates with a rack (think of a geared
wheel opened up and laid flat). When the
steering wheel is turned, the pinion turns,
moving the rack to the left or right. This
movement is transmitted through the track
rods to the steering arms at the wheels.
RadiatorA liquid-to-air heat transfer device
designed to reduce the temperature of the
coolant in an internal combustion engine
cooling system.
RefrigerantAny substance used as a heat
transfer agent in an air-conditioning system.
R-12 has been the principle refrigerant for
many years; recently, however, manufacturers
have begun using R-134a, a non-CFC
substance that is considered less harmful to
the ozone in the upper atmosphere.
Rocker armA lever arm that rocks on a shaft
or pivots on a stud. In an overhead valve
engine, the rocker arm converts the upward
movement of the pushrod into a downward
movement to open a valve.
Adjusting spark plug gap
Plastigage
Gasket

3261 Jaguar XJ6
NNeutral start switch -7•5
Notes for UK readers -0•4, REF•3
Number plate light - 12•12
OObtaining diagnostic code output -6•3
Oil cooler -3•6
Oil filter -1•6
Oil gauge - 12•7
Oil pump -2A•15
Oil seals -2A•5, 2A•17, 2B•17, 7•7, 8•4, 8•5, REF•5
Oil,differential -1•2, 1•11, 1•20
Oil,engine -0•11, 0•16, 1•2, 1•6
On Board Diagnosis (OBD) system -6•2
Open circuit check - 12•2
Output shaft -7•7
Oxygen sensor -6•4
PPads (brake) -9•1, 9•2
Painting - 11•2
Parking lights - 12•11
Piston rings -2B•15
Pistons -2B•9, 2B•12, 2B•17
Poisonous or irritant substances -0•5
Power hydraulic system -0•16
fluid - 1•9
Power steering - 10•10, 10•11
fluid - 0•13, 0•16
Propshaft -1•18, 8•1, 8•2, 8•3
Punctures- 0•8
RRadiator -3•4
grille - 11•5
Radio - 12•7, REF•1
Rear lights - 12•12
Receiver/drier -3•12
Regulator (window) - 11•10
Relays - 12•3
Repair procedures - REF•5
Reversing lights -7•5, 12•12
Road test -1•14
Roadside repairs-0•6et seq
Routine maintenance and servicing-1•1et seq
Rust holes - 11•2
SSafety first -0•5
Scalding -0•5
Scratches - 11•2Screw threads and fastenings - REF•5
Seat belts -1•13, REF•9
Seats - 11•14, REF•9
Self-levelling rear suspension system - 10•3
Servo -1•12, 9•1, 9•9
Shift cable -7•4
Shock absorber - 10•4, 10•6, REF•9, REF•10
Shoes (brake) -1•20, 9•11
Short circuit check - 12•1
Side marker lights - 12•11
Spare parts - REF•4
Spark plugs -1•7, 1•14
Speakers - 12•7
Speed sensor -6•7
Spoiler - 11•5
Springs - 10•5, 10•6, REF•10
Starter motor -5•7
Steering - See Suspension and steering systems
Steering wheel and column - 11•13, 12•5, REF•8
Sump -2A•14
Sunroof - 12•14
Supplementary air valve -4•13
Suspension and steering systems- 1•12, 10•1et seq, REF•9, REF•10
fault finding - REF•16, REF•17
Switches -4•1, 7•5, 9•13, 12•5, 12•6, 12•12
TTail lights - 12•12
Temperature gauge - 12•7
Temperature sender unit -3•7
Thermostat -3•2
Throttle body -4•10
Throttle potentiometer -6•5
Tie-rod ends - 10•9
Timing chains -2A•6
Tools - REF•5, REF•6, REF•7
Top Dead Centre (TDC) for number one piston -2A•2
Torque converter -7•7
Towing -0•6
Trim panels - 11•7, 11•13
Tyres - 0•14, 10•11, REF•11
UUK readers information -0•4, REF•3
Universal joint -8•1, 8•2, 8•5
Upholstery - 11•1
VVacuum gauge checks -2B•3
Valve cover -2A•3
Valve lifters -2A•9
Valves -2B•8
Vehicle identification - REF•4, REF•9
Vehicle support - REF•1
Vinyl trim - 11•1
Voltage checks - 12•1
REF•24Index