Contents - Volkspage

4B.8 Fuel system: multi-point injection models
10.3a Idle speed adjustment screw 10.3b Exhaust CO adjustment screw
location
location
10 Fuel injection system
adjustment -
general information
1 If a fault appears in the fuel injection system
first ensure that all the system wiring
connectors are securely connected and free of
corrosion. Then ensure that the fault is not due
to poor maintenance; ie, check that the air
cleaner filter element is clean, the spark plugs
are in good condition and correctly gapped,
the cylinder compression pressures are
correct, the ignition timing is correct and the
engine breather hoses are clear and
undamaged, referring to Chapter 1, Chapter 2A
and Chapter 5B for further information.
2 If these checks fail to reveal the cause of the
problem the vehicle should be taken to a
suitably equipped VW dealer for testing. A
diagnostic connector is incorporated in the
engine management system wiring harness,
into which a dedicated electronic test
equipment can be plugged. The test equipment
is capable of “interrogating” the engine
management system ECU electronically and
accessing its internal fault log. In this manner,
faults can be pinpointed quickly and simply,
even if their occurrence is intermittent. Testing
all the system components individually in an
attempt to locate the fault by elimination is a
time consuming operation that is unlikely to be
fruitful (particularly if the fault occurs
dynamically) and carries a high risk of damage
to the ECU’s internal components.
3 Experienced home mechanics equipped
with an accurate tachometer and a carefullycalibrated
exhaust gas analyser may be able to
check the exhaust gas CO content and the
engine idle speed; if these are found to be out
of specification, then the vehicle must be taken
to a suitably-equipped VW dealer for
assessment. Idle speed and exhaust CO
adjustment screws are provided
(see illustrations), but adjustment will not be
possible if the engine management system has
detected and stored a fault in one of the
fuelling or ignition system components. For this
reason, all fault codes must be erased from the
engine management system memory before
the idle speed and exhaust CO settings can be
checked and adjusted - this operation must be
carried out by a WV dealer with the required
test equipment.
Caution: inaccurate CO adjustment may
cause overfuelling and the risk of serious
catalytic converter damage.
General information
1 The G-charger develops its maximum
pressure at full load and so cannot be tested
with the vehicle stationary. It is recommended
that the boost pressure is measured by a WV
dealer, using a rolling road. However, if this is
not possible, the measurement may be made
as follows.
2 Connect a vacuum hose T-piece in line with
the vacuum supply to the fuel pressure
regulator. Route a length of vacuum hose
from the T-piece to a pressure test gauge in
the cabin. Close the bonnet, ensuring that the
vacuum hose is not trapped. Enlist the help of
an assistant to hold the gauge and read off
measurements from the passenger seat.
3 Drive the vehicle on a strip of private road
(not the public highway) at full throttle in
second gear whilst simultaneously depressing
the footbrake to maintain an engine speed of
4000 rpm. Have your assistant record the
maximum boost pressure indicated.
Caution: Do not maintain these driving
conditions for more than 10 seconds.
4 Compare the measurement with that listed
in the Specifications. If the boost pressure is
low, check the tension of the drivebelts (as
described in Chapter 1) and make sure that
there are no leaks or blockages in the inlet
system, before condemning the G-charger.
Removal
A
Warning: Do not run the engine
with the G-charger air inlet hose
! disconnected; the depression at
the inlet can build up very
suddenly if the engine speed raised and
there is the risk of foreign objects being
sucked in.
10.3c Protective cap (arrowed) fitted to
exhaust CO pre-catalyst sampling pipe
(not fitted to later vehicles)
Caution: Thoroughy clean around all oil pipe
unions before disconnecting them, to
prevent the ingress of dirt. Store
components in a sealed container to prevent
contamination. Cover the G-charger air inlet
ducts to prevent debris entering and clean
using lint-free cloths only.
5 Remove the screws and lift off the
G-charger cover plates.
6 Remove the auxiliary drivebelts (Chapter 1).
7 Slacken the clips and detach the air inlet
and delivery ducting from the G-charger
ports. Cover the open ports with plastic
sheeting secured with elastic bands, to
prevent the ingress of foreign material.
8 Slacken and withdraw the banjo bolts at the
oil supply and return unions. Recover the
sealing washers and discard them - new ones
must be used on refitting. Plug the open
oilways to minimise oil loss and prevent
contamination.
9 Slacken and withdraw the G-charger
mounting bracket bolts, supporting the unit as
the last bolt is withdrawn.
10 Remove the G-charger from the engine
bay together with its mounting bracket and
the drivebelt pulleys.
Refitting
11 Refit the G-charger by following the
removal procedure in reverse, noting the
following points:
a) Ensure that the air inlet ducting is
completely free of debris, before refitting
it and securing the clips.
b) Use new sealing washers when
reconnecting the oil supply and return
unions; tighten the banjo bolts to the
specified torque.
c) With reference to Chapter 1, refit and
tension the auxiliary drivebelts.
12 Unleaded petrol -
general information and usage
Refer to the information in the Specifications
at the start of this Chapter, and in
Chapter 4A.