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8 Unleaded petrol - general
information and usage
Note: The information given in this Chapter is
correct at the time of writing. If updated
information is thought to be required, check
with a Peugeot dealer. If travelling abroad,
consult one of the motoring organisations (or a
similar authority) for advice on the fuel
available.
All Peugeot 205 single-point fuel injection
models are designed to run on fuel with a
minimum octane rating of 95 (RON). All
models are equipped with catalytic
converters, and therefore must be run on
unleaded fuel only. Under no circumstances
should leaded fuel be used, as this may
damage the catalytic converter.
Super unleaded petrol (97/98 RON) can
also be used in all models if wished, though
there is no advantage in doing so.
9 Fuel injection systems -
general information
Bosch Mono-Jetronic A2.2
system
The Mono-Jetronic A2.2 system is a
single-point fuel injection system
incorporating a catalytic converter in the
exhaust system.
The fuel pump, located in the fuel tank,
pumps the fuel through a filter to the single
fuel injector. The electronic control unit (ECU),
which is triggered by the ignition circuit, sends
impulses to the injector, which sprays fuel
upstream of the throttle valve. A constant fuel
pressure is maintained by a fuel pressure
regulator, which returns excess fuel to the fuel
tank. The ECU also receives information from
various sensors to determine engine
temperature, speed and load, and the quality
of air entering the engine. The sensors inform
the ECU of throttle position, inlet air
temperature, coolant temperature, and
exhaust gas oxygen content. Engine speed
and crankshaft position information is
provided by the ignition circuit. All the
information supplied to the ECU is computed
and compared with pre-set values stored in
the ECU memory, to determine the required
period of injection. The injector operates four
times per engine cycle, and the injector
opening duration is varied to control the
quantity of fuel delivered.
The ECU constantly varies the fuel mixture
and engine idle speed to provide optimum
engine efficiency under all operating
conditions, and to reduce exhaust gas
emissions. The mixture strength is accurately
controlled to maintain it within the operating
limits of the catalytic converter.
MMFD Mono-point G5 and G6
systems
The Mono-point G5 and G6 systems are
single-point fuel injection systems also
incorporating a catalytic converter in the
exhaust system. The only difference between
the two systems is that the idle speed is
controlled via a control valve on the G5
system, and via a control motor on the G6
system. The system operation is as described
above for the Mono-Jetronic system and is
under the overall control of an electronic
control until (ECU), which also controls the
ignition system.
10 Fuel injection system -
testing and adjustment
3
Testing
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. 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 valve clearances are correctly adjusted,
the cylinder compression pressures are
correct, the ignition timing is correct (where
adjustable), and that the engine breather
hoses are clear and undamaged, referring to
Chapters 1, 2 and 5 for further information.
2 If these checks fail to reveal the cause of
the problem, the vehicle should be taken to a
suitably-equipped Peugeot dealer for testing.
A wiring block connector is incorporated in
the engine management circuit, into which a
special electronic diagnostic tester can be
plugged. The tester will locate the fault quickly
and simply, alleviating the need to test all the
system components individually, which is a
time-consuming operation that also carries a
risk of damaging the ECU.
Adjustment
3 Experienced home mechanics with a
considerable amount of skill and equipment
(including a tachometer and an accurately
calibrated exhaust gas analyser) may be able
to check the exhaust CO level and the idle
speed. However, if these are found to be in
need of adjustment, the car must be taken to
a suitably-equipped Peugeot dealer for further
testing.
4 On both single-point fuel injection systems,
no adjustment of the CO level and idle speed
is possible, these being under the complete
control of the ECU. Should the idle speed or
exhaust gas CO level be incorrect, then a fault
is likely to be present in the fuel injection
system.
11 Mono-Jetronic A2.2 system
components - removal and
refitting
3
Note: Check the availability of individual
components with your Peugeot dealer before
dismantling.
Fuel pressure regulator
Note: Refer to the warning note in Section 1
before proceeding.
1 The fuel pressure regulator (consisting of a
valve operated by a spring-loaded diaphragm
and a metal cover) is secured by four screws
to the top of the throttle body (see
illustration). Although the unit can be
dismantled for cleaning, if required (once the
air inlet trunking and the fuel injector wiring
clip have been removed for access), it should
not be disturbed unless absolutely necessary.
2 Note that the regulator assembly is only
available as part of the complete throttle body
assembly; no individual components can be
renewed separately.
3 If the regulator cover is removed, note its
orientation on the throttle body before
removal, to ensure correct refitting.
Fuel injector
Note: Refer to the warning note in Section 1
before proceeding. If a faulty injector is
suspected, before condemning the injector, it
is worth trying the effect of one of the
proprietary injector-cleaning treatments.
4 Disconnect the battery negative lead.
5 Remove the air inlet trunking from the top of
the throttle body.
6 Remove the Torx screws securing the
injector wiring connector to the top of the
throttle body, then carefully lift off the
connector (see illustrations).
7 Withdraw the injector (see illustration).
Recover and discard the injector sealing rings.
8 Refitting is the reverse of the removal
procedure, noting the following points.
a) Always renew both sealing rings: apply a
smear of grease to each ring, to ease
injector refitting.
b) Ensure that the injector is refitted so that
its connector pins align with the
connector when the connector is
correctly located on the top of the throttle
body.
Fuel system - single-point fuel injection engines 4B•3
4B
11.1 Fuel injector wiring clip (A), and fuel
pressure regulator securing screws (B) -
Mono-Jetronic A2.2 system