brake OPEL VECTRA 1988 Service Service Manual

42Where applicable, screw the pressure-
proportioning valves into the base of the
cylinder.
43Refit the master cylinder, as described in
Section 15.
17Master cylinder (ABS) -
general
The master cylinder fitted to models with
ABS cannot be dismantled, and no attempt
should be made at overhaul.
If faulty, the complete unit must be
renewed, as described in Section 15.
18Vacuum servo - description
and testing
Description
1The vacuum servo is fitted between the
brake pedal and the master cylinder, and
provides assistance to the driver when the
pedal is depressed, reducing the effort required
to operate the brakes. The unit is operated by
vacuum from the inlet manifold. With the brake
pedal released, vacuum is channelled to both
sides of the internal diaphragm. However,
when the pedal is depressed, one side of the
diaphragm is opened to atmosphere, resulting
in assistance to the pedal effort. Should the
vacuum servo develop a fault, the hydraulic
system is not affected, but greater effort will be
required at the pedal.
Testing
2The operation of the servo can be checked
as follows.
3With the engine stopped, destroy the
vacuum in the servo by depressing the brake
pedal several times.
4Hold the brake pedal depressed and start
the engine. The pedal should sink slightly as
the engine is started.
5If the pedal does not sink, check the servo
vacuum hose for leaks.
6If no defects are found in the vacuum hose,
the fault must lie in the servo itself.7No overhaul of the servo is possible, and if
faulty, the complete unit must be renewed.
19Vacuum servo - removal and
refitting
4
Note: During the 1989 model year, some
vehicles were produced with the brake pedal
height incorrectly set, resulting in the brake
pedal resting approximately 15.0 mm (0.6 in)
above the clutch pedal instead of 4.0 mm
(0.16 in below). The correct pedal height can
be set by adjusting the vacuum servo
operating fork dimension, as described in
paragraphs 15 and 16
Removal
1Disconnect the battery negative lead.
2Working inside the vehicle, remove the
lower trim panel from the driver’s footwell.
3Disconnect the wiring plug from the brake
lamp switch, then twist the switch anti-
clockwise and remove it from its bracket.
4Pull the spring clip from the right-hand end
of the servo fork-to-pedal pivot pin.
5Using a pair of pliers, pull back the end of
the pedal return spring from the pedal, to
enable the servo fork-to-pedal pivot pin to be
removed. Withdraw the pivot pin.
6Remove the windscreen cowl panel, as
described in Chapter 11, then remove the
windscreen wiper motor and linkage as
described in Chapter 12.7Remove the coolant expansion tank as
described in Chapter 3.
8Pull the vacuum pipe from the brake servo.
9Unscrew the two securing nuts, and
carefully withdraw the brake master cylinder
from the studs on the servo. Move the master
cylinder forwards slightly, taking care not to
strain the brake pipes.
10Remove the two plugs covering the servo
securing bolts from the cowl panel (see
illustrations).
11Using a Allen key or hexagon bit, unscrew
the servo securing bolts and remove them
completely, then lift the servo from the
bulkhead (see illustrations).
12If desired, the mounting bracket can be
removed from the servo by unscrewing the
four securing nuts. Note that the bracket will
stick to the servo, as it is fitted with sealing
compound.
13The servo cannot be overhauled, and if
faulty, the complete unit must be renewed.
Refitting
14Before refitting the servo, check that the
operating fork dimension is correct as follows.
15Measure the distance from the end face of
the servo casing to the centre of the pivot pin
hole in the end of the operating fork. The
distance should be 144.0 mm (5.6 in). To
make accurate measurement easier, insert a
bolt or bar of similar diameter through the
pivot pin hole, and measure to the centre of
the bolt or bar (see illustration).
Braking system 9•15
19.11A Unscrew the securing bolts . . .19.15 Measuring the servo operating fork
dimension using a bolt inserted through
the pivot pin hole19.11B . . . and withdraw the servo
19.10B . . . to expose the servo securing
bolts19.10A Remove the plugs . . .
9

16If adjustment is necessary, slacken the
locknut, turn the fork to give the specified
dimension, then tighten the locknut.
17Where applicable, coat the contact faces
of the servo and the mounting bracket with
sealing compound, then refit the bracket to
the servo, and tighten the securing nuts to the
specified torque.
18Coat the threads of the servo securing
bolts with locking fluid, then fit the servo to
the bulkhead and tighten the securing bolts.
19Refit the securing bolt cover plugs to the
cowl panel.
20Refit the master cylinder to the servo, and
tighten the securing nuts to the specified
torque.
21Reconnect the vacuum pipe to the servo.
22Refit the coolant expansion tank, as
described in Chapter 3.
23Refit the windscreen wiper motor and
linkage as described in Chapter 12, then refit
the windscreen cowl panel.
24Further refitting is a reversal of removal.
On completion, test the operation of the
servo, as described in Section 18.
20ABS hydraulic modulator -
removal and refitting
4
Note: Refer to Section 2, and the note at the
beginning of Section 3, before proceeding
Removal
1Disconnect the battery negative lead.
2Remove the brake fluid reservoir cap, and
secure a piece of polythene over the filler
neck with a rubber band, or by refitting the
cap. This will reduce the loss of fluid during
the following procedure.
3Remove the securing screw, and withdraw
the plastic cover from the hydraulic
modulator.
4Remove the two clamp screws, and lift off
the modulator wiring harness clamp (see
illustration).
5Disconnect the modulator wiring plug,
levering it from the socket with a screwdriver if
necessary.6Unscrew the brake fluid pipe union nuts,
and disconnect the pipes from the modulator.
Be prepared for fluid spillage, and plug the
open ends to prevent dirt ingress and further
fluid loss. Move the pipes just clear of the
modulator, taking care not to strain them.
7Unscrew the three modulator securing nuts
(see illustration), then tilt the modulator
slightly, and withdraw it upwards from its
bracket, sufficiently to gain access to the
earth lead securing nut at the front lower edge
of the modulator.
8Unscrew the securing nut and disconnect
the earth lead, then withdraw the modulator
from the vehicle, taking care not to spill brake
fluid on the vehicle paintwork.
9If a new modulator is to be fitted, pull the
two relays from the top of the old modulator,
and transfer them to the new unit. No attempt
must be made to dismantle the modulator.
Refitting
10Before refitting the modulator, check that
the bolts securing the mounting bracket to the
body panel are tight, and that the modulator
rubber mountings are in good condition.
Renew the rubber mountings if necessary.
11Refitting is a reversal of removal,
remembering the following points.
12Make sure that the earth lead is
reconnected before fitting the modulator to its
mounting bracket.13On completion, remove the polythene
sheet from the brake fluid reservoir filler neck,
and bleed the complete brake hydraulic
system, as described in Section 3.
14Check that the ABS warning lamp
extinguishes when first starting the engine
after the modulator has been removed. At the
earliest opportunity, take the vehicle to a
Vauxhall dealer, and have the complete
system tested, using the dedicated ABS test
equipment.
21ABS wheel sensors - removal
and refitting
3
Note: Refer to Section 2 before proceeding
Front wheel sensor
Removal
1Disconnect the battery negative lead.
2Where applicable, remove the wheel trim,
then loosen the relevant front roadwheel bolts
and apply the handbrake. Jack up the front of
the vehicle, and support on axle stands (see
“Jacking and Vehicle Support”) positioned
under the body side members. Remove the
roadwheel.
3Unclip the sensor wiring connector from the
retaining clip under the wheel arch, then
separate the two halves of the wiring
connector, prising them apart with a
screwdriver if necessary (see illustration).
4Using a Allen key or hexagon bit, unscrew
the bolt securing the wheel sensor to its
mounting bracket, then carefully lever the
sensor from the bracket using a screwdriver
(see illustration). Recover the seal ring.
Refitting
5Examine the condition of the seal ring, and
renew if necessary.
6Refitting is a reversal of removal,
remembering the following points.
7Smear a little grease on the sensor casing
before fitting it to the bracket.
8Do not fully tighten the roadwheel bolts until
the vehicle is resting on its wheels.
9Check that the ABS warning lamp
extinguishes when first starting the engine
after a wheel sensor has been removed. At
9•16Braking system
20.4 ABS hydraulic modulator (cover
removed)
1 Wiring harness
clamp screws2 Earth lead
3 Relays
21.3 Front wheel sensor wiring under
wheelarch - DOHC model
1 ABS sensor connector
2 Disc pad wear sensor wiring connector
21.4 ABS front wheel sensor securing bolt
(arrowed) - DOHC model20.7 ABS hydraulic modulator securing
screws (arrowed)

8Disconnect the battery negative lead.
9Unclip the lid and open the relay box, then
pull out the relay (see illustration).
Refitting
10Refitting is a reversal of removal, with
reference to paragraph 6.
24Rear brake pressure-
proportioning valves -
removal and refitting
4
Note: Refer to the note at the beginning of
Section 3 before proceeding. Note also that
the valve must only be renewed in pairs, and
both valves must be of the same calibration.
Ensure that correct type of valves are fitted.
The bodies have been stamped for easier
identification.
Master cylinder-mounted valves
Removal
1Remove the brake fluid reservoir cap, and
secure a piece of polythene over the filler
neck with a rubber band, or by refitting the
cap. This will reduce the loss of fluid during
the following procedure.
2Locate a container beneath the master
cylinder, to catch the brake fluid that will be
released.
3Identify the two lower brake pipes for
position, then unscrew the union nuts and
disconnect the pipes from the proportioning
valves in the base of the master cylinder. Plug
the open ends of the pipes to prevent dirt
ingress.
4Unscrew the proportioning valves from the
master cylinder, and plug the open ends of
the cylinder to prevent dirt ingress.
Refitting
5Refitting is a reversal of removal, but on
completion, remove the polythene from the
brake fluid reservoir filler neck, and bleed the
complete hydraulic system, as described in
Section 3.
Rear underbody-mounted valves
Removal
6Proceed as described in paragraph 1.
7Chock the front wheels, then jack up the
rear of the vehicle, and support securely on
axle stands (see “Jacking and Vehicle
Support”) positioned under the body side
members.
8Working under the rear of the vehicle,
unscrew the union nut and disconnect the
brake pipe from one of the valves. Be
prepared for fluid spillage, and plug the open
end of the pipe to prevent dirt ingress and
further fluid spillage.
9Similarly, disconnect the flexible hose from
the valve.
10Pull the valve retaining clip from the
bracket on the underbody, noting that on
certain models, the retaining clip also secures
the ABS sensor wiring, and withdraw the valve
(see illustration).
11Repeat the procedure for the other valve.
Refitting
12Proceed as described in paragraph 5.
25Brake fluid pipes and hoses
- general, removal and refitting
4
Note: Refer to the note at the beginning of
Section 3, before proceeding.
General
1When checking the condition of the
system’s pipes and/or hoses, carefully check
that they do not foul other components such
as the power steering gear pipes (where
applicable), so that there is no risk of the
pipes chafing. If necessary use clips or ties to
secure braking system pipes and hoses well
clear of other components.
Rigid pipes
Removal
2Some of the commonly used brake pipes
can be obtained from Vauxhall parts dealers,
ready-formed and complete with unions, but
other brake pipes must be prepared using
4.75 mm (0.19 in) diameter brake pipe. Kits for
making the brake pipes can be obtained from
certain motor accessory shops.
3Before removing a brake pipe, remove the
brake fluid reservoir cap, and secure a piece
of polythene over the filler neck with a rubber
band, or by refitting the cap. This will reduce
the loss of fluid when the pipe is
disconnected.4Jack up the vehicle, and support securely
on axle stands (see “Jacking and Vehicle
Support”) positioned under the body side
members.
5To remove a brake pipe, unscrew the
unions at each end, and release the pipe from
the retaining clips.
Refitting
6Refitting is a reversal of removal, taking
care not to overtighten the unions.
7On completion, remove the polythene from
the brake fluid reservoir filler neck, and bleed
the relevant hydraulic circuit(s), as described
in Section 3.
Flexible hoses
Removal
8Proceed as described previously for the
rigid pipes, but note that a flexible pipe must
never be installed twisted, although a slight
“set” is permissible to give it clearance from
adjacent components.
Refitting
9When reconnecting a flexible hose to a
front brake caliper, note that the sealing rings
on the union bolt must be renewed.
26Handbrake - adjustment
2
Models with rear drum brakes
1The handbrake will normally be kept in
correct adjustment by the self-adjusting
action of the rear brake shoes. However, due
to cable stretch over a period of time, the
travel of the handbrake lever may become
excessive, in which case the following
operations should be carried out.
2Chock the front wheels, jack up the rear of
the vehicle, and support securely on axle
stands (see “Jacking and Vehicle Support”)
positioned under the body side members.
3Fully release the handbrake.
4Turn the knurled nut on the cable adjuster
(mounted on the torsion beam), until the brake
shoes can just be heard to rub when the rear
wheels are turned by hand in the normal
direction of rotation (see illustration).
9•18Braking system
23.9 ABS surge arrester relay (arrowed)
26.4 Handbrake cable adjuster. Knurled
nut arrowed - all SOHC models24.10 Brake pressure-proportioning valve
on rear underbody - DOHC model
1 Valve 2 Retaining clip

5Loosen the adjuster nut until the wheels are
just free to turn.
6The handbrake must start to operate with
the lever on the second notch of the ratchet.
7On completion of adjustment, check the
handbrake cables for free movement, and
apply a little grease to the adjuster threads to
prevent corrosion.
8Lower the vehicle to the ground.
Models with rear disc brakes
9Where applicable, remove the wheel trims,
then loosen the rear roadwheel bolts and
chock the front wheels. Jack up the rear of the
vehicle, and support securely on axle stands
(see “Jacking and Vehicle Support”)
positioned under the body side members.
Remove the roadwheels.
10Pull the handbrake lever as far as the
second notch on the ratchet.
11On DOHC models fitted with a catalytic
converter, unscrew the four securing nuts and
withdraw the exhaust centre box heat shield
by carefully sliding it round the centre box.
12On all SOHC models, loosen the knurled
nut on the cable adjuster (mounted on the
torsion beam).
13On DOHC models, loosen the nut
securing the cable equaliser yoke to the
handbrake lever operating rod.
14Using a screwdriver inserted through the
adjuster hole in one of the discs/hubs (see
illustration), turn the adjuster wheel until the
brake shoes can just be heard to rub when the
disc/hub is turned by hand in the normal
direction of rotation.
15Turn the adjuster wheel back until the
disc/hub is just free to turn.
16Repeat paragraphs 14 and 15 on the
remaining side of the vehicle.
17Tighten the nut on the cable adjuster or
the equaliser, as applicable, until the brakeshoes just begin to operate. Check that the
shoes operate equally on both wheels.
18Fully release the handbrake, then apply it
again.
19The discs/hubs must lock when the
handbrake lever reaches the sixth notch on
the ratchet. If necessary, turn the nut on the
cable adjuster or equaliser, as applicable, to
achieve this.
20Where applicable, refit the exhaust heat
shield.
21Refit the roadwheels and lower the vehicle
to the ground. Do not fully tighten the
roadwheel bolts until the vehicle is resting on
its wheels.
27Handbrake cable - removal
and refitting
3
Models with rear drum brakes
Removal
1The handbrake cable is in two sections. The
longer section runs from the handbrake
operating rod, through the adjuster, to the
right-hand brake assembly. The shorter
section runs from the adjuster to the left-hand
brake assembly. The two sections of the cable
can be renewed independently.
2Where applicable, remove the wheel trim(s),
then loosen the relevant rear roadwheel bolts.
Chock the front wheels, jack up the rear of the
vehicle, and support securely on axle stands
(see “Jacking and Vehicle Support”)
positioned under the body side members.
Remove the roadwheel(s).
3Note the routing of the handbrake cable(s),
as an aid to refitting.
4Remove the relevant brake drum(s), with
reference to Section 11.
Longer cable
Removal
5Note the length of exposed thread at the
handbrake cable adjuster on the torsion
beam, then unscrew the adjuster nut from the
threaded rod.
6Disconnect the cable from the handbrake
lever operating rod on the vehicle underbody
(see illustration).
7Detach the cable from the guides on the
underbody. Note that the cable can be fed
through certain guides, but in some cases, the
guide brackets must be bent away from the
underbody to allow the cable to be withdrawn.
8Detach the cable from the adjuster on the
torsion beam.
9Unhook the cable end from the lever on the
brake shoe, then using a screwdriver, prise
out the lockplate that secures the handbrake
cable in the backplate.
10Withdraw the cable from the vehicle,
releasing it from the guide on the torsion
beam.
Refitting
11Refitting is a reversal of removal,
remembering the following points.
12Screw the adjuster nut onto the threaded
rod to the position noted before removal.
13Ensure that the handbrake cable is routed
as noted before removal.
14Refit the brake drum, (Section 11).
15Before refitting the roadwheel(s) and
lowering the vehicle to the ground, adjust the
handbrake, as described in Section 26.
Shorter cable
Removal
16Note the length of exposed thread at the
handbrake cable adjuster on the torsion
beam, then unscrew the adjuster nut from the
threaded rod. Continue as described in
paragraphs 8 to 10.
Braking system 9•19
27.6 Handbrake cable connection to handbrake lever operating
rod
1 Handbrake cable
2 Connecting link3 Handbrake lever operating rod26.14 Using a screwdriver to turn the handbrake adjuster wheel -
model with rear disc brakes
9

Refitting
17Proceed as described in paragraphs 11
to 15 inclusive.
Models with rear disc brakes
(SOHC)
General
18The procedure is as described for models
with rear drum brakes, remembering the
following points.
19Ignore the references to removal and
refitting of the brake drum.
20Note that there is no lockplate securing
the handbrake cable to the brake backplate,
but the return spring must be unhooked from
the cable end.
21On models with a catalytic converter,
when removing the longer cable, unscrew the
four securing nuts and withdraw the exhaust
centre box heat shield by carefully sliding it
round the centre box.
DOHC models
Removal
22The left and right-hand handbrake cables,
and the equaliser yoke, are removed as an
assembly on DOHC models.
23Loosen the rear roadwheel bolts, then
chock the front wheels, jack up the rear of the
vehicle, and support securely on axle stands
(see “Jacking and Vehicle Support”)
positioned under the body side members.
Remove the roadwheels.
24Note the routing of the handbrake cables,
as an aid to refitting.
25On models with a catalytic converter,
unscrew the four securing nuts and withdraw
the exhaust centre box heat shield by
carefully sliding it round the centre box.
26Note the length of exposed thread at the
cable equaliser yoke, then unscrew the
securing nut and disconnect the equaliser
yoke from the handbrake lever operating rod.
27Unhook the cable ends from the brake
shoe operating levers and the return springs
(see illustration).
28Detach the cable from the guides on the
underbody and the semi-trailing arms. Note
that the cables can be fed through certainguides, but in some cases, the guide brackets
may have to be bent away from the
underbody to allow the cables to be
withdrawn.
29Withdraw the cables and equaliser
assembly from the vehicle.
Refitting
30Refitting is a reversal of removal,
remembering the following points.
31Use a new self-locking nut to secure the
equaliser yoke to the handbrake lever
operating rod, and screw the nut onto the rod
to the position noted before removal.
32Ensure that the cables are routed as
noted before removal.
33Before refitting the roadwheels and
lowering the vehicle to the ground, adjust the
handbrake, as described in Section 26.
28Handbrake lever - removal
and refitting
3
Removal
1Disconnect the battery negative lead.
2Jack up the vehicle, and support on axle
stands (see “Jacking and Vehicle Support”)
positioned securely under the body side
members.
3On models with a catalytic converter,
unscrew the four securing nuts and withdraw
the exhaust centre box heat shield by
carefully sliding it round the centre box.
4On all SOHC models, note the length of
exposed thread at the handbrake cable adjuster
on the torsion beam, then slacken the adjuster
to enable the cable to be disconnected from the
handbrake lever operating rod. Disconnect the
cable from the operating rod and slide the
rubber sealing grommet from the underbody
and operating rod.
5On DOHC models, note the length of
exposed thread at the handbrake cable
equaliser yoke, then unscrew the securing nut
and disconnect the equaliser yoke from the
handbrake lever operating rod. Slide the
rubber sealing grommet from the underbody
and operating rod.
6Remove the front passenger seat, as
described in Chapter 11.7Remove the rear section of the centre
console, as described in Chapter 11.
8Access to the handbrake lever-to-floor
mounting bolts is provided by slits in the
carpet. If no slits are provided, either carefully
cut some, or release and fold back the carpet.
9Unscrew the mounting bolts, and withdraw
the handbrake lever sufficiently to disconnect
the handbrake “on” warning lamp switch
wiring (see illustration).
10Disconnect the wiring and withdraw the
handbrake lever and operating rod from the
vehicle.
11A worn ratchet segment can be renewed
by driving the securing sleeve from the
handbrake lever, using a metal rod or a bolt of
similar diameter (see illustration).
12Drive the new sleeve supplied with the
new segment into the lever to permit a little
play between the segment and lever.
13If desired, a new pawl can be fitted if the
original pivot rivet is drilled out (see
illustration).
14Rivet the new pawl so that the pawl is still
free to move.
15The handbrake “on” warning lamp switch
can be removed from the lever assembly after
unscrewing the securing bolt.
Refitting
16Refitting is a reversal of removal,
remembering the following points.
17Refit the rear section of the centre
console, as described in Chapter 11.
18Refit the front passenger seat, as
described in Chapter 11.
9•20Braking system
28.13 Drilling out the handbrake lever pawl
pivot pin
28.11 Driving out the handbrake lever
ratchet segment securing sleeve28.9 Handbrake lever securing bolts
(arrowed)27.27 Handbrake cable end fitting at brake
shoe - DOHC model
1 Operating lever
2 Cable bracket on semi-trailing arm

19On DOHC models, use a new self-locking
nut to secure the equaliser yoke to the
handbrake lever operating rod, and screw the
nut onto the rod to the position noted before
removal.
20On SOHC models, tighten the cable
adjuster to expose the length of thread noted
before removal.
21Before lowering the vehicle to the ground,
adjust the handbrake, (Section 26).
29Brake pedal - removal and
refitting
3
Removal
1Disconnect the battery negative lead.
2Remove the lower trim panel from the
driver’s footwell.3Disconnect the wiring plug from the brake
lamp switch, then twist the switch anti-
clockwise and remove it from its bracket.
4Pull the spring clip from the right-hand end
of the servo fork-to-pedal pivot pin (see
illustration).
5Using a pair of pliers, pull back the end of
the pedal return spring from the pedal, to
enable the servo fork-to-pedal pivot pin to be
removed. Withdraw the pivot pin (see
illustration).
6Pull the locking clip from the left-hand end
of the pedal pivot pin.
7Unscrew the nut from the left-hand end of
the pivot pin, then slide the pivot pin from the
right-hand end of the pedal mounting bracket.
If necessary, tap the end of the pivot pin with
a soft-faced hammer to free the splines from
the mounting bracket. Recover any washers
that may be positioned on the pivot pin,
noting their locations.8Withdraw the pedal and return spring.
Refitting
9Refitting is a reversal of removal,
remembering the following points.
10Ensure that the pedal return spring is
correctly located on the pedal before refitting.
11Coat the pedal pivot pin with a little
molybdenum disulphide grease.
12Ensure that any washers on the pedal
pivot pin are positioned as noted before
removal.
Braking system 9•21
29.5 Brake pedal assembly removed from vehicle
1 Locking clip 2 Pedal return spring 3 Pedal pivot pin29.4 Brake servo fork-to-pedal pivot pin spring clip (arrowed)
9

31This engine is also fitted with an EGR
(exhaust gas recirculation) valve and
secondary air injection (AIR - Air Injection
Reactor), to conform to the latest European
exhaust emission limits (as from 1996). The
EGR returns a specific amount of exhaust gas
into the combustion process. This in turn
reduces the formation of nitrogen oxides
(No
x). The secondary air injection system has
an electrically driven air pump that injects air
into the exhaust manifold, reducing the
amount of CO and HC emissions.
2Fuel injection system -
precautions
The fuel injection system is pressurised,
therefore extra care must be taken when
disconnecting fuel lines. When disconnecting
a fuel line union, loosen the union slowly, to
avoid a sudden release of pressure that may
cause fuel to spray out.
Fuel pressure checking must be entrusted
to a Vauxhall dealer, or other specialist, who
has the necessary special equipment.
3System testing - general
3
General
1Apart from basic electrical tests, there is
nothing that can be done by the owner to test
individual fuel system components.2If a fault arises, check first that it is not due
to poor maintenance. Check that the air
cleaner filter element is clean, the spark plugs
are in good condition and correctly gapped.
Check also that the engine breather hoses are
clear and undamaged and that the throttle
cable is correctly adjusted. If the engine is
running very roughly, check the compression
pressures (Chapter 1) and remember the
possibility that one of the hydraulic tappets
might be faulty, producing an incorrect valve
clearance.
3If the fault is thought to be due to a dirty
injector, it is worth trying one of the
established injector-cleaning treatments
before renewing, perhaps unnecessarily, the
injector.
4If the fault persists, check the ignition
system components (as far as possible).
5If the fault is still not eliminated, work
methodically through the system, checking all
fuses, wiring connectors and wiring, looking
for any signs of poor connections, dampness,
corrosion, dirt or other faults.
6Once the system components have been
checked for signs of obvious faults, take the
vehicle to a Vauxhall dealer for the full system
to be tested on special equipment.
7Do not attempt to “test” any component,
but particularly the ECU, with anything other
than the correct test equipment, available at a
Vauxhall dealer. If any of the wires to be
checked lead to a component such as the
ECU, always first unplug the relevant
connector from the system components so
that there is no risk of the component being
damaged by the application of incorrect
voltages from test equipment.
4Air cleaner - removal and
refitting
2
Note:If ‘round type’ air filter is fitted, follow
procedure in Chapter 4A.
Removal
1Unclip the coolant expansion tank hose
from the air cleaner cover, and move it to one
side out of the way.2Loosen the clamp screw and disconnect
the air trunking from the airflow meter (see
illustration).
3Disconnect the battery negative lead, then
disconnect the wiring plug from the airflow
meter.
4Release the two securing clips from the left-
hand side of the air cleaner cover, and
unscrew the two captive securing screws
from the right-hand side, then lift off the
cover.
5Lift out the filter element.
6Loosen the preheat hoses, fastening nuts.
7Undo the nuts securing the 2 rubber block
studs which are secured through the lower
half of the air cleaner housing.
8Some models are fitted with an inlet air
resonance box, to reduce induction noise.
This box is located under the wheel arch, and
connects to a pipe on the air inlet tube.
9The resonance box must be removed
before the air inlet tube can be removed. To
do this, first apply the handbrake, then jack up
the front of the vehicle, and support securely
on axle stands placed under the body side
members.
10Remove the securing screws, and
withdraw the lower splash shield from the
wing to expose the resonance box.
11Unscrew the single securing screw, and
pull the resonance box from the connector
tube (see illustrations).
12If desired, the air inlet tube can be
removed after pulling off the connector tube
from under the wing (see illustration).
4B•4Fuel and exhaust systems - fuel injection models
4.12 Removing the resonance box
connector tube4.11B . . . and withdraw the resonance box4.11A Remove the securing screw . . .
4.2 Loosening the air trunking clamp
screw at the airflow meter
Warning: Many of the
procedures in this sub-Section
require the removal of fuel lines
and connections that may result
in some fuel spillage. Before carrying out
any operation on the fuel system refer to
the precautions given in Safety first! at
the beginning of this Manual and follow
them implicitly. Petrol is a highly
dangerous and volatile liquid, and the
precautions necessary when handling it
cannot be overstressed.

regulator vacuum pipe should be routed over
the top of the camshaft cover breather hoses.
21On models with the Multec system note
also the following:
a)Fit the new diaphragm so that it locates in
the throttle body groove.
b)Ensure that the spring and spring seat are
correctly engaged with each other and
with the diaphragm and regulator cover.
Then press the cover over its locating
dowels and hold it in place while the
screws are tightened.
c)Tighten the screws carefully to the
specified torque wrench setting.
22On completion, check the regulator for
leaks, pressurising the system by switching
the ignition on and off several times, before
the engine is started.
22Idle speed adjuster - removal
and refitting
3
Note:Idle speed adjustment on models fitted
with Multec systems, is not possible, as it is
controlled by the ECU. Refer to Section 1.
Removal
SOHC models (except Multec system)
1Disconnect the battery negative lead.
2Disconnect the wiring plug from the idle
speed adjuster (see illustration).
3The adjuster can be removed complete with
its connecting hoses, or separately, leaving
the hoses in place.4Loosen the relevant clamp screws, then
disconnect the hoses, and withdraw the idle
speed adjuster (see illustration).
DOHC models
5Disconnect the battery negative lead.
6Loosen the clamp screw, and disconnect
the hose from underneath the air box on the
throttle body. Remove the clamp from the
hose.
7Apply the handbrake, then jack up the front
of the vehicle, and support securely on axle
stands (see “Jacking and Vehicle Support”)
placed under the body side members.
8Remove the engine undershield, as
described in Chapter 11.
9Working underneath the vehicle,
disconnect the wiring plug from the idle speed
adjuster, which is located underneath the inlet
manifold above the starter motor (see
illustration).
10Loosen the clamp screw and disconnect
the remaining idle speed adjuster hose from
the inlet manifold, then withdraw the adjuster
downwards complete with the hoses.
11If the hoses are to be removed from the
adjuster, mark their locations before removal
so that they can be correctly reconnected.
Once the adjuster has been refitted, it is
impossible to swap the hose positions.
Refitting
12Refitting is a reversal of removal. On
DOHC models ensure that the idle speed
adjuster rests horizontally, with the wiring
routed over the top of the coolant hose. If thewiring is routed under the coolant hose, this
may cause the idle speed adjuster to be bent
downwards, resulting in a restriction or
fracture in the air hose to the inlet manifold.
23Throttle position sensor -
removal and refitting
3
Removal
SOHC models
1Disconnect the battery negative lead.
2Disconnect the wiring plug from the throttle
position sensor (see illustration).
3Remove the two securing screws and
withdraw the sensor from the throttle body
(see illustration).
DOHC models
4Disconnect the battery negative lead.
5Disconnect the wiring plug from the air
mass meter. Recover the sealing ring.
6Loosen the clamp screw securing the air
trunking to the right-hand end of the air mass
meter.
7Using an Allen key or hexagon bit, unscrew
the four bolts securing the air box to the
throttle body. Lift the air box from the throttle
body, and disconnect the hose from the base
of the air box, then withdraw the air box/air
mass meter assembly.
8Disconnect the wiring plug from the throttle
position sensor wiring plug (see illustration).
Fuel and exhaust systems - fuel injection models 4B•11
22.9 Idle speed adjuster (arrowed) viewed
from underneath vehicle -
DOHC model
23.8 Disconnecting the throttle position
sensor wiring plug - DOHC model23.3 Removing a throttle position sensor
securing screw - SOHC early model23.2 Disconnecting the throttle position
sensor wiring plug - early SOHC models
22.4 Withdrawing the idle speed adjuster
complete with hoses - SOHC model
(except with Multec systems)22.2 Disconnecting the idle speed adjuster
wiring plug - SOHC models (except with
Multec systems)
4B

28Fuel injectors (except Multec
system) - removal and refitting
3
Note:Refer to Section 2 before proceeding.
New O-rings must be used when refitting the
injectors. Where applicable, a tachometer and
an exhaust gas analyser will be required to
check the idle mixture on completion
Removal
SOHC models
1Disconnect the battery negative lead.
2Unscrew the union nut, and disconnect the
brake servo vacuum hose from the inlet
manifold.
3Remove the idle speed adjuster, complete
with hoses, referring to Section 22 if
necessary.4Disconnect the vacuum pipe from the top
of the fuel pressure regulator.
5Disconnect the wiring harness housing from
the fuel injectors, and move it to one side,
taking care not to strain the wiring. Pull up on
the wiring harness housing, and compress the
wiring plug retaining clips to release the
harness housing from the injectors.
6Remove the four bolts from the brackets
securing the fuel rail to the inlet manifold, then
lift the fuel rail complete with fuel injectors
sufficiently to enable the injector(s) to be
removed (see illustrations). Take care not to
strain the fuel hoses.
7To remove an injector from the fuel rail,
prise out the metal securing clip using a
screwdriver, then pull the injector from the fuel
rail (see illustrations).
Refitting
8Overhaul of the fuel injectors is notpossible, as no spares are available. If faulty,
an injector must be renewed.
9Begin refitting by fitting new seals to both
ends of each fuel injector (see illustration).
Even if only one injector has been removed,
new seals should be fitted to all four injectors.
10Refitting is a reversal of removal, ensuring
that all hoses, pipes and wires are correctly
reconnected.
11On completion, where applicable, check
and if necessary adjust the idle mixture, as
described in Section 20.
DOHC models
Removal
12Disconnect the battery negative lead.
13Loosen the clamp screw securing the air
trunking to the left-hand end of the air mass
meter.
14Using an Allen key or hexagon bit, unscrew
the four bolts securing the air box to the throttle
body. Lift the air box from the throttle body,
and disconnect the hose from the base of the
air box, then withdraw the air box.
15Position a wad of rag beneath one of the
fuel hose unions on the fuel rail, to absorb the
fuel that will be released as the union is
disconnected.
16Slowly loosen the fuel hose union to
relieve the pressure in the fuel line, then
disconnect the hose from the fuel rail. Be
prepared for fuel spillage, and take adequate
fire precautions. Plug the end of the fuel hose,
to prevent dirt ingress and further fuel leakage.
17Repeat paragraphs 15 and 16 for the
remaining fuel hose-to-fuel rail union.
18Disconnect the two breather hoses from
the rear of the camshaft cover. Disconnect the
larger hose from the throttle body, and
remove the hose completely.
19Disconnect the vacuum pipe from the top
of the fuel pressure regulator.
20Disconnect the wiring plug from the air
mass meter. Recover the sealing ring.
21Disconnect the wiring plug from the
throttle position sensor.
22Slide the end of the throttle cable from the
throttle valve lever on the throttle body, then
unbolt the cable bracket from the inlet
manifold, and move it to one side (see
illustration).
Fuel and exhaust systems - fuel injection models 4B•13
28.6C . . . and lift the fuel rail from the inlet
manifold (inlet manifold removed for
clarity) - SOHC model
28.22 Throttle cable bracket securing
bolts (arrowed) - DOHC model28.9 Fit new seals to the injectors
28.7B . . . then pull the injector from the
fuel rail - SOHC model28.7A Withdraw the securing clip . . .
28.6B . . . and inner fuel rail securing
bolts . . .28.6A Remove the outer . . .
4B

Refitting
5Refitting is a reversal of the removal
procedure, ensuring that the wiring plugs are
correctly reconnected and that the unit is
located securely.
36Knock sensor and module
(X16 SZ models) - removal
and refitting
3
Removal
1The knock sensor fitted to the X16 SZ
engine is located on the cylinder block below
the inlet manifold, between cylinders 2 and 3.
2Disconnect the battery negative lead.
3Remove the wiring and unscrew the unit
from the block.
4The module and control unit are located on
the left-hand side of the engine compartment
behind the battery. To remove, disconnect the
wiring multiplug and remove the retaining
bolts (see illustration).
5There is no provision for testing the knock
sensor or module without dedicated Vauxhall
test equipment. Check for external damage
and replace if necessary.
Refitting
6Refitting is a reversal of the removal
procedure, ensuring that the wiring plugs are
correctly reconnected and that the units are
located securely.
37Knock sensor (Simtec
system) - removal and refitting
3
Removal
1Disconnect the battery negative lead.
2Disconnect wiring harness plug, from inlet
air temperature sensor and wiring harness
plug, from hot mass air flow meter.
3Remove crankcase ventilation hoses.
4Remove coolant hoses from air inlet hoses,
hot film mass air flow meter complete with air
inlet hoses, from upper part of air cleaner and
throttle body.5Press retaining clip for 1st and 4th cylinder
injectors in plug strip (with screwdriver)
towards fuel distributor pipe - lifting plug strip
at the same time. On the underside of the plug
strip there are a total of 6 plug connections, 4
of which are for the injectors.
6Disconnect wiring harness plug for knock
sensor from the plug strip.
7Connect a 1 metre length of separate cable
to knock sensor wiring harness plug (note
routing).
8Remove knock sensor from cylinder block
(see illustration).
9Disconnect knock sensor cable from
separately attached cable, separate cable
remains in engine compartment.
Refitting
10Refitting is a reversal of removal, but note
the following.
11Before refitting ensure that the sensor is
spotlessly clean. Clean the entire contact
surface of the sensor must lie directly on the
cylinder block. Do not use any form of
washers.
12Carefully refit sensor into the block.
Tighten to the correct torque.
13Guide knock sensor cable between ridges
on inlet manifold using separate cable -
ensure correct routing.
14Remove the cable.
15Insert the wiring harness plug for the
knock sensor, into the plug strip.
16Correctly align the spring clips for theinjectors as they may prevent engagement of
the plug strip. Correct contact between the
plug strip and the injector is essential.
17When connecting plug strip, an audible
‘click’ should be heard.
18Ensure that hoses are in good condition
and installed securely with the two clamps.
38Inlet manifold (SOHC without
Multec) - removal and refitting
3
Note:Refer to warning in Section 2, before
proceeding. Use a new gaskets when refitting.
Removal
1Disconnect the battery negative lead.
2Remove the idle speed adjuster and its
hoses, referring to Section 22, if necessary.
3Release the securing clip, then disconnect
the throttle cable and balljoint from the throttle
valve lever. Slide the throttle cable grommet
from the bracket on the inlet manifold, and
move the throttle cable to one side out of the
way.
4Loosen the clamp screw and disconnect
the air trunking from the throttle body.
5Unscrew the union nut and disconnect the
brake servo vacuum hose from the inlet
manifold(see illustration).
6Disconnect the camshaft cover breather
hose from the throttle body.
7Disconnect the coolant hoses from the
throttle body. Be prepared for coolant
spillage, and clamp or plug the open ends of
the hoses, to prevent further coolant loss.
8Disconnect the wiring plug from the throttle
position sensor.
9Disconnect the vacuum pipe from the top
of the fuel pressure regulator.
10Disconnect the wiring harness housing
from the fuel injectors and move it to one side,
taking care not to strain the wiring. Pull up on
the wiring harness housing, and compress the
wiring plug retaining clips to release the
harness housing from the injectors.
11Disconnect the fuel hoses from the fuel
rail. Be prepared for fuel spillage, and take
adequate fire precautions. Clamp or plug the
open ends of the hoses, to prevent dirt
ingress and further fuel leakage.
Fuel and exhaust systems - fuel injection models 4B•17
38.5 Disconnecting the brake servo
vacuum hose -
SOHC models37.8 Knock sensor and wiring
(Simtec system)
1 Sensor2 Securing bolt
36.4 Knock sensor and module (X16 SZ models)
1 Sensor2 Module3 Sensor securing bolt
4B