1998 JAGUAR X308 evaporative canister purge valve

The E
VAP canister purge valve controls th
e flow rate of fuel vapour drawn into the engine during the canister purge
operation. The valve is opened by a vacu um feed from the induction elbow : the vacu um feed is controlled by the integral
valve solenoid and is applied when the so lenoid is energised. The solenoid is pulsed on (energised) and off by a fixed
frequency (100Hz) variable pulse width control signal (pulse width modulation). By varying the pulse on to off time, the
ECM controls the duty cycle of the valve (time that the valve is open to time closed) and thus the vapour flow rate to the
engine.
With no ECM signal applied to the va lve solenoid, the valve remains closed.
Can
ister Purge Operation
The
following pre-conditions are ne
cessary for purging to commence :
aft
er battery disconnection/reconnection, engine
management adaptations must be re-instated.
engine has run for
at least 8 seconds.
engi

ne coolant temperature is not less than 70 °C.
engine

not running in the fuel
cut off condition (eg overrun).
t
he adaptive fuel correction
function has not registered a rich or lean failure
t
he evaporative emission leak test has not failed
no faults have been diagnosted in th
e rel
evant sensor and valve circuits -
Air Flow Meter (AFM), Engine Coolant
Temperature sensor, Evaporativ e Canister Purge valve and Canister Close Valve (CCV).
If these conditions have been satisfied, purging is started. If any failures are registered, purging is inhibited.
The canister(s) is purged during each driv e cycle at various rates in accordance with the prevailing engine conditions. The
engine management software st ores a map of engine speed (RPM) against engine load (grams of air inducted / rev). For
any given engine speed and load, a vapour purge rate is assigned (purge rate increases with engine speed and load).
The preset purge rates are base d on the assumption of a vapour concentratio n of 100%. The actual amount of vapour is
measured by the closed loop fueling system : the input of evaporative fuel into the engine causes the outputs from the
upstream oxygen sensors to change, the am ount of change providing a measure of the vapour concentration. This feedback
causes the original purge rate to be adju sted and also reduces the amount of fuel input via the injectors to maintain the
correct air to fuel ratio.
Engine speed/load mapping and the corresp onding purge rates are different for single canister, running loss and ORVR
evaporative systems.

Thi s
system uses a single charcoal canister with a pressure
control valve between the canister and the fuel tank vapour
outlet. A vacuum control pipe is connecte d from the engine intake induction elbow to the pressure control valve. The vapour
outlet from the fuel tank is taken via a safety rollover valve fitted to the re moveable flange at the top of the tank.
With the engine stopped, the pressure control valve is closed, maintaining a slight positive pre ssure in the tank : any further
increase in pressure causes the valve to open and release vapour to the canister.
When the engine is running, manifold depr ession (via the vacuum control pipe) holds the pressure control valve open. Air is
drawn into the tank to maintain atmospheric pressure as fuel is used and vapourised fuel is deposited in the charcoal
canister.
Canister purge operation is as described in Evaporative Emissions Control.
It e
m
Par
t
Number
De
scr
iption
1—Evaporative flan
ge assembly
2—Vapour outlet rol
lover valve
3—Tank vapour outlet pipe
4—Breather
pipe
5—Pressure control valve
6—Induct
ion vacuum control pipe
7—Charcoal can
i
ster
8—Canister vapour outlet pipe
9—EVAP canister purge v
a
lve
10—Vacuu
m
control sign
al from induction
11—EVAP ca
nister purge valve outlet
12—Canist
er vent
to atmosphere
Single Ca
nister System

The ru nning loss
system has the following features :
a
normall
y open pressure control valve is fi
tted at the lefthand side of the tank.
two charcoal
canisters are connected in series to reduce th
e concentration of fuel in vapour vented to atmosphere.
a t
ank pressure sensor and canister close
valve are fitted to allow the on-board di agnostic facility to test for leaks in
the fuel and evaporative system.
The pressure control valve allows continuo us venting of vapour to the charcoal canisters during normal running but prevents
fuel entering the vent line duri ng refueling. Fuel vapour from the tank passes through the valve to the lefthand canister and
a third pipe connects the valve to the fill er neck. When refueling, the difference in pressure betw een the tank interior and
the open filler neck causes the valve to cl ose, shutting off the vapour vent line. Wh en the fuel cap is replaced, the pressures
are equalised and the pressure control valve opens the vent line to the canisters.
The canister close valve is a solenoid operated device controlled by the ECM. The valve is normally open and is closed only
during the leak test sequence.
The fuel pressure sensor is fitted to th e evaporative loss flange and provides a volt age to the ECM which is proportional to
Ite
m
Par
t
Number
De
scr
iption
1—Vapour outl
et rol
lover valve
2—Evaporative flan
ge assembly
3—Tank vapour outlet pipe
4—Breather pipe
5—Pressure control
valve
6—Vapour pipe to canister
7—Charcoal cani
sters
8—Cani
st
er close valve
9—Vent pi
pe ai
r filter
10—Canister purge ou
tlet pipe
11—Vapour pipe conn
ecting canisters
12—EVAP canister purge v
a
lve
13—Vacuu
m
control signal from induction elbow
14—EVAP pu
rge valve outlet to induction elbow

Running Loss Sys
tem

tank vapou
r pressure.
Canister purge operation is as described in Evaporative Emissions Control.
Evaporative Flange Assembly

The evaporative loss flange assembly is fitted to the top of the tank via a seal and locking ring. The assembly is removeable
complete with the fitted components.
The vapour vent / rollover valve and pressure sensor are a pu sh fit via sealing grommets. The fuel pump connector is push
fitted and crimped into a location tu be on the underside of the flange.
It
em
Par
t Number
De
scription
1—Vapour vent /

rollover protection valve
2—Pres

sure sensor
3—Fue

l pump connector
4—Evaporative loss flange locking rin

g

The system has the
following features :
o
n
-board refueling vapour recovery (ORVR) to reduce the fu
el vapour vented directly to atmosphere from the filler
nozzle when refueling.
two ch arcoal
canisters are connected in series to reduce th
e concentration of fuel in vapour vented to atmosphere.
a t
ank pressure sensor and canister close
valve are fitted to allow the on-board di agnostic facility to test for leaks in
the fuel and evaporative system.
The canister close valve is a solenoid operated device controlled by the ECM. The valve is normally open and is closed only
during the leak test sequence.
The fuel pressure sensor is fitted to th e evaporative loss flange and provides a volt age to the ECM which is proportional to
tank vapour pressure.
Op era
tion of ORVR System
The ORVR system enabl
e
s fuel vapour generated during re-fueling to be collected by
the charcoal canisters. During normal
running of the vehicle, the vapour is collected and purged in the same way as for non-ORVR systems.
Ite
m
Par
t
Number
De
scr
iption
1—Grade vent
valve outl
et
2—Vapour outl
et from fil
l level vent valve (FLVV)
3—F
L
VV pressure relief valve outlet pipe
4—N
a
rrow diameter fuel filler tube
5—Charcoal can
i
sters
6—Cani
st
er close valve
7—Vent pi
pe ai
r filter
8—Vapour pipe
conn
ecting canisters
9—Canister purge ou
tlet pipe
10—EVAP canister purge v a
lve (engine bay)
11—Vacuu
m
control signal from induction elbow
12—EVAP pu
rge valve outlet to induction elbow

Running Loss with On-board R
efuelin
g Vapour Recovery (ORVR) System

The OR
VR system features are :
N

arrow fuel filler pipe and tank check valve.
Fue

l level vent valve (FLVV) fitted to the evaporative flan
ge and consisting of a two stage shut-off valve with rollover
protection and a pressure relief valve.
Grade ven
t valve with rollover protection, fitted to the ev
aporative flange and with an outlet pipe connected to the
FLVV vapour outlet pipe.
Large bore vapour vent pipes.

The fuel filler pipe has a reduced diameter between the nozzle guide and the tank, providing a liquid seal when re-fueling
and preventing the fuel vapour venting directly to atmosphere. There is no breather tube fitted between the tank and the
filler nozzle. To prevent spit back when re-fueling, a check valv e is fitted at the lower end of the filler pipe inside the tank
(see Figure).
During re-fueling, the tank is vented to atmosphere via the fuel level vent valv e (FLVV), large bore vapour pipes and the
charcoal canisters. The FLVV incorp orates a float valve which is closed by the rising fuel level, creating a back pressure and
causing the fuel delivery to stop. In the closed position, the FLVV also sets the fuel level.
With the FLVV closed (tank full), any increase in pressure or overfilling is relieved by a separate rollover protected grade
vent valve. The outlet from this valve feeds into the main FLVV vapour outlet pipe, bypassing the closed FLVV.
When the fuel level is below full, the FLVV opens to allow unrestricted venting via the canisters.
A pressure relief valve is incorp orated into the FLVV assembly and has an outlet pipe to the filler nozzle,. If a blockage or
other restriction (eg, canister close valve failing in the closed position) occurs in the vapour vent system, the pressure reli ef
valve opens to allow venting to atmosphere via the filler nozzle guide and fuel filler cap.
Canister purge operation is as described in Evaporative Emissions Control.
Filler Tube and Check Valve

Ite
m
Part
Number
Descr
iption
1—Fu

el tank pressure sensor (if applicable)
2—Engine m

anagement ECU
3—EVAP canister purge va

lve
4—EVAP ca

nister close valve (if applicable)
5—Engine
mana
gement fusebox - IGN supply
Circuit diagram
,
evaporative emissions systems

Pinpoint Tests
P
INPOINT TEST A : P0442; SYSTEM LEAK DETECTED
•
NOTE: For K-Line or Vacutec equipment connection, see bulletin 05.1-29, or Vacutec operating instructions
TE

ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
A

1: CHECK PIPEWORK, ETC FOR LEAKS
Carr

y out a visual inspection of all accessible pipes, connectors and components. Rectify any faults
noted.
1
U
sing K-line or Vacutec equipment, check the
joints/connections in the following order:
Fi
ller cap
Cani

ster purge valve
Underfl

oor purge line connectors
Carbon

canister connections and vapor hoses
Cani

ster close valve and it's atmospheric port (disconnect the air vent tube if necessary)
2
Was

a fault found?
Yes Rectify the fault as necessary. Re peat the K-line or Vacutec test. CLEAR the DTC. Carry out a full
Evaporative system monitor drive cycle. Recheck DT Cs. For additional information, see "diagnostic
drive cycles" above.
No GO to A2
.
A2: CHECK
THE CA
NISTER PURGE VALVE FOR FLOW
Ru
n the engine.
1
Make sure the canister purge

valve is operating.
2
Using a flowmeter

(or a small piece
of paper) at the CCV inlet tube, confirm flow through the canister
purge valve.
3
Is th
ere flow through the canister purge valve?
Yes Possible intermittent faul t with vapor hoses, O-ring seals. Carefully check condition of hoses and
seals. Replace any suspect seals. Repeat the K-line or Vacutec test. CLEAR the DTC. Carry out a full
Evaporative system monitor drive cycle. Recheck DT Cs. For additional information, see "diagnostic
drive cycles" above.
No INSTALL a new canister purge valve.
REFER to Evaporative Emission Canister Purge Valve
- in t
his section.
CLEAR the DTC. Carry out a full Evap orative system monitor drive cycle.
P
INPOINT TEST B : P0444, P0445; PURGE VALVE CIRCUIT OPEN/SHORT CIRCUIT
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
B1: CHECK

THE PURGE VALVE DRIV
E CIRCUIT FOR HIGH RESISTANCE
Turn the ignition swi
tch to the OFF
position.
1
Di
sconnect the battery negative terminal.
Vehicles with AJ26 engine:
Disc
onnect the ECM electrical connector, EM15
Di

sconnect the purge valve electrical connector, EM39
Meas

ure the resistance between EM15,
pin 03 (PN) and EM39, pin 02 (PN)
Vehicles with AJ27 engine:
Disc
onnect the ECM electrical connector, EM80
Di

sconnect the purge valve electrical connector, EM39
Meas

ure the resistance between EM80, pin 01 (UY) and EM39, pin 02 (UY)
2
Is th

e resistance greater than 5 ohms?
Yes REPAIR the high resistance circuit. For additional information, refer to the wiring diagrams. CLEAR the
DTC. Carry out a full Evaporative system monitor drive cycle. For additional information, see