Peugeot 405 Haynes (petrol). Manual - part 17

15 Bosch Monopoint system

components - removal and
refitting

Note: Check the availability of individual
components with your Peugeot dealer before
dismantling.

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.
1 Remove the inlet air temperature sensor as
described later in this Section.
2 Lift out the injector and recover its lower
sealing ring.
3 Refitting is a reversal of the removal
procedure ensuring that the injector sealing
ring(s) and injector cap O-ring are in good
condition. When refitting the injector cap
ensure that the injector pins are aligned with
the cap terminals, the terminals are marked “+”
and “-” for identification (see illustrations).

Fuel pressure regulator

Note: Refer to the warning note in Section 1
before proceeding. At the time of writing, the
fuel pressure regulator assembly was not
available separately from the throttle body
assembly. Refer to a Peugeot dealer for the
latest information. Although the unit can be
dismantled for cleaning, if required, it should
not be disturbed unless absolutely necessary.
4 Disconnect the battery negative terminal.
5 Remove the air cleaner-to-throttle body
duct, using the information given in Section 2.
6 Using a marker pen, make alignment marks
between the regulator cover and throttle
body, then slacken and remove the cover
screws (see illustration). As the screws are
slackened, place a clean rag over the cover to
catch any fuel spray which may be released.
7 Lift off the cover, then remove the spring
and withdraw the diaphragm, noting its
correct fitted orientation. Remove all traces of
dirt and examine the diaphragm for signs of
splitting. If damage is found, it will probably
be necessary to renew the throttle body
assembly.

8 Refitting is a reverse of the removal
procedure, ensuring that the diaphragm and
cover are fitted the correct way round, and
that the retaining screws are securely
tightened.

Idle control stepper motor

9 Disconnect the battery negative terminal.
10 Depress the retaining clip and disconnect
the wiring connector from the idle control
stepper motor.
11 Undo the retaining screws and remove
the motor from the front of the throttle body
(see illustration).
12 Refitting is a reverse of the removal
procedure, ensuring that the motor retaining
screws are securely tightened.

Throttle potentiometer

13 The throttle potentiometer is a sealed unit,
and under no circumstances should it be

disturbed. For this reason, on some models, it
is secured to the throttle body assembly by
tamperproof screws. If the throttle
potentiometer is faulty, the complete throttle
body assembly must be renewed - refer to
your Peugeot dealer for the latest information.

Inlet air temperature sensor

Note: Refer to the warning note in Section 1
before proceeding.
14 The inlet air temperature sensor is an
integral part of the throttle body injector cap.
To remove the cap, first disconnect the
battery negative terminal, then remove the air
cleaner-to-throttle body duct using the
information given in Section 2.
15 Undo the three retaining screws and
remove the circular plastic ring from the top of
the throttle body and recover its sealing ring
(see illustrations).
16 Depress the retaining clip and disconnect

Fuel/exhaust systems - single-point fuel injection models 4B•7

15.3c On refitting, ensure cap terminals

are aligned with injector pins (arrowed)

15.15a Undo the three retaining screws

(arrowed) . . .

15.11 Idle control stepper motor

retaining screws (arrowed)

15.6 Fuel pressure regulator

retaining screws (arrowed)

15.3b . . . then lift off the cap and withdraw

the injector

15.3a Undo the injector cap screw, noting

the use of rag to catch fuel spray . . .

15.15b . . . then lift off the plastic ring and

recover the sealing ring

the wiring connector from the injector wiring
connector (see illustration).
17 Undo the injector cap retaining screw,
then lift off the cap and recover the gasket
and/or sealing ring (as applicable). Note that
as the cap screw is slackened, place a rag
over the injector to catch any fuel spray which
may be released.
18 Refitting is a reversal of the removal
procedure ensuring that the injector cap
gasket and/or O-ring is in good condition.
Take care to ensure that the cap terminals are
correctly aligned with the injector pins and
securely tighten the cap retaining screw.

Coolant temperature sensor

19 Refer to Chapter 3.

Electronic control unit (ECU)

20 The ECU is located in the plastic box
which is mounted onto the rear of the battery
mounting tray.
21 To remove the ECU, first disconnect the
battery.
22 Unclip the cover from the box, then lift the
retaining clip and disconnect the wiring
connector from the ECU.
23 Undo the retaining nut and release the
relay unit from the rear of the ECU box.
24 Undo the retaining screws and remove
the ECU and box assembly from the battery
tray. If necessary, undo the retaining screws
and separate the ECU and box.
25 Refitting is a reverse of the removal
procedure ensuring that the wiring connector
is securely reconnected.

Fuel injection system relay unit

26 The relay unit is mounted onto the rear of
the ECU plastic box which is situated directly
behind the battery.
27 To remove the relay unit, first disconnect
the battery.
28 Undo the retaining nut, then disconnect
the wiring connector and remove the relay unit
from the vehicle.
29 Refitting is the reverse of removal,
ensuring that the relay unit is securely clipped
in position.

Crankshaft sensor

30 The crankshaft sensor is situated on the
front face of the transmission (clutch) housing.

31 To remove the sensor, first disconnect the
battery negative terminal.
32 Trace the wiring back from the sensor to
the wiring connector, and disconnect it from
the main harness.
33 Prise out the rubber grommet, then undo
the retaining bolt and withdraw the sensor
from the transmission.
34 Refitting is a reverse of the removal
procedure. Ensure that the sensor retaining
bolt is securely tightened, and that the
grommet is correctly seated in the
transmission housing.

Vehicle speed sensor

35 The vehicle speed sensor is an integral
part of the speedometer drive housing. Refer
to Chapter 7A, Section 7 for removal and
refitting details.

16 Magneti Marelli system

components - removal and
refitting

Note: Check the availability of individual
components with your Peugeot dealer before
dismantling.

Fuel injector

Note: Refer to the warning note in Section 1
before proceeding.
Note: If a faulty injector is suspected, before
condemning the injector, it is worth trying the
effect of one of the proprietary injector-
cleaning treatments. If this fails, the vehicle
should be taken to a Peugeot dealer for
testing using the appropriate specialist
equipment. At the time of writing, it appears
that neither the fuel injector nor its seals are
available separately and, if faulty, the
complete upper throttle body assembly must
be renewed. Refer to your Peugeot dealer for
further information on parts availability.
1 Disconnect the battery negative terminal.
2 Remove the air cleaner-to-throttle body
duct using the information given in Section 2.
3 Release the retaining tangs and disconnect
the injector wiring connector (see
illustration).
4 Undo the retaining screw, then remove the
retaining clip and lift the injector out of the

housing, noting its sealing ring. Note that as
the screw is slackened, place a rag over the
injector to catch any fuel spray which may be
released.
5 Refitting is a reverse of the removal
procedure ensuring that the injector sealing
ring is in good condition.

Fuel pressure regulator

Note: Refer to the warning note at the start of
this Section before proceeding.
Note: At the time of writing, it appears that the
fuel pressure regulator is not available
separately. If the fuel pressure regulator
assembly is faulty, the complete upper throttle
body assembly must be renewed. Refer to a
Peugeot dealer for further information on parts
availability. Although the unit can be
dismantled for cleaning, if required, it should
not be disturbed unless absolutely necessary.
6 Disconnect the battery negative terminal.
7 Remove the air cleaner-to-throttle body
duct using the information given in Section 2.
8 Using a suitable marker pen, make
alignment marks between the regulator cover
and throttle body, then undo the four retaining
screws. Note that as the screws are
slackened, place a rag over the cover to catch
any fuel spray which may be released.
9 Lift off the cover, then remove the spring
and withdraw the diaphragm whilst noting its
correct fitted orientation. Remove all traces of
dirt and examine the diaphragm for splitting. If
damage is found, it will be necessary to renew
the complete upper throttle body assembly as
described earlier in this Section.
10 Refitting is a reverse of the removal
procedure ensuring that the diaphragm and
cover are fitted the correct way around and
the retaining screws are securely tightened.

Idle control stepper motor

11 Disconnect the battery negative terminal.
12 To remove the stepper motor, depress the
retaining tabs and disconnect the wiring
connector. Undo the two retaining screws and
withdraw the motor from the side of the
throttle body assembly.
13 Refitting is a reverse of removal.

Throttle potentiometer

14 Disconnect the battery negative terminal,
then depress the retaining tabs and
disconnect the wiring connect from the
throttle potentiometer (see illustration).
15 Undo the two retaining screws and
remove the throttle potentiometer from the
side of the throttle body assembly.
16 Refitting is a reversal of the removal
procedure ensuring that the throttle
potentiometer tang is correctly engaged with
the throttle spindle.

Inlet air temperature sensor

17 The inlet air temperature sensor is
screwed into the underside of the upper
throttle body where it is situated on the left-
hand side of the fuel injector.

4B•8 Fuel/exhaust systems - single-point fuel injection models

15.16 Disconnecting the injector wiring

connector. Injector screw is arrowed

16.3 Injector wiring connector (arrowed)

18 To remove the sensor, first disconnect the
battery negative terminal.
19 Disconnect the wiring connector, then
undo the retaining screw and remove the inlet
air temperature sensor from the throttle body.
Note: The sensor retaining screw is very
difficult to reach. If it proves impossible to
unscrew, the throttle body will have to be
removed to permit sensor removal.
20 Refitting is a reverse of removal.

Manifold absolute pressure
(MAP) sensor

21 The MAP sensor is mounted onto a
bracket which is situated on the engine
compartment bulkhead, behind the throttle
body.
22 To remove the sensor, first disconnect the
battery negative terminal.
23 Slacken and remove the three retaining
bolts, then free the MAP sensor from the
bracket. Disconnect the wiring connector and
vacuum hose and remove the sensor from the
engine compartment.
24 Refitting is a reversal of the removal
procedure.

Coolant temperature sensor

25 Refer to Chapter 3.

Crankshaft sensor

26 Refer to Section 14.

Electronic control unit (ECU)

27 Refer to Section 14.

Fuel injection system relay unit

28 Refer to Section 14.

Throttle body heating element

29 The throttle body heating element is
situated in the front of the throttle body.
30 To remove the element, first disconnect
the battery negative terminal.
31 Remove the air cleaner housing-to-
throttle body duct using the information given
in Section 2.
32 Disconnect the wiring connectors from
the inlet air temperature sensor and the
injector. Also disconnect the main wiring
connector from the throttle body and free the
connector from its mounting bracket.
33 Undo the retaining screws and free the
accelerator mounting bracket from the throttle
body. As the bracket is released, recover the
spring from the front of the heating element.
34 Ease the heating element out from the
throttle housing and remove it along with the
wiring connector and wiring harness. Examine
the O-ring for signs of damage or
deterioration and renew if necessary.
35 Refitting is a reversal of removal; where
necessary, use a new O-ring.

17 Inlet manifold -

removal and refitting

Removal

1 Remove the throttle body (Section 12).
2 Drain the cooling system (see Chapter 1).
3 Slacken the retaining clip and disconnect
the coolant hose(s) from the manifold.
4 Slacken the retaining clip and disconnect
the vacuum servo unit hose from the left-hand
side of the manifold.
5 Make a final check that all the necessary
vacuum/breather hoses have been
disconnected from the manifold.
6 Unscrew the retaining nuts, then
manoeuvre the manifold away from the head
and out of the engine compartment. Note that
there is no manifold gasket.

Refitting

7 Refitting is the reverse of the removal
procedure, noting the following points:

a) Ensure that the manifold and cylinder

head mating surfaces are clean and dry,
and apply a thin coating of suitable

sealing compound to the manifold mating
surface. Refit the manifold and tighten its
retaining nuts to the specified torque.

b) Ensure that all relevant hoses are

reconnected to their original positions and
securely held (where necessary) by their
retaining clips.

c) Refit the throttle body as described in

Section 12.

d) On completion, refill the cooling system

as described in Chapter 1.

18 Exhaust manifold -

removal and refitting

Removal

1 Refer to Chapter 4A, Section 15, noting that
the lambda (oxygen) sensor wiring connectors
should be disconnected. Alternatively, care
must be taken to support the front pipe, to
avoid any strain being placed on the sensor
wiring.

Refitting

2 Refitting is the reverse of the removal
procedure, noting the following points:

a) Examine all the exhaust manifold studs for

signs of damage and corrosion; remove
all traces of corrosion, and repair or
renew any damaged studs.

b) Ensure that the manifold and cylinder

head sealing faces are clean and flat, and
fit the new manifold gaskets. Tighten the
manifold retaining nuts to the specified
torque.

c) Reconnect the front pipe to the manifold.

19 Exhaust system -

general information, removal
and refitting

Refer to Chapter 4A, Section 16, however

note that it will be necessary to disconnect
the lambda (oxygen) sensor wiring connectors
in order to remove the front pipe/complete
system. On refitting, ensure that the sensor
wiring is retained by all the relevant retaining
clips so that it is in no danger of contacting
the hot exhaust/engine.

Fuel/exhaust systems - single-point fuel injection models 4B•9

16.14 Throttle potentiometer wiring

connector (arrowed)

System type

XU5 (BFZ), XU7 (LFZ), XU10 (RFX), XU10 (R6D) engine . . . . . . . . . . . . .

Magneti Marelli 8P multi-point

XU5 (BFZ) engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sagem-Lucas 4GJ multi-point

XU7 (LFZ) engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Bosch Motronic MP5.1 multi-point

XU9 (D6A and D6D) engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Bosch L3.1-Jetronic multi-point

XU9 (D6D) engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Bosch Motronic MP3.1 multi-point

XU9 (DKZ and DFZ) engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Bosch LU2-Jetronic multi-point

XU9 (DKZ and DFV), XU9 (DFW 16-valve) engine . . . . . . . . . . . . . . . . .

Bosch Motronic M1.3 multi-point

XU9 (D6C) 16-valve engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Bosch Motronic ML4.1 multi-point

XU10 (RFY 16-valve), XU10 (RFT) engine . . . . . . . . . . . . . . . . . . . . . . . .

Bosch Motronic MP3.2 multi-point

Fuel system data

Fuel pump type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electric, external (early models) or internal (later models)

Fuel pump regulated constant pressure (at specified idle speed):

Bosch L3.1 system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.5 bars

Other Bosch systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3.0 ± 0.2 bars

Magneti Marelli system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.5 ± 0.2 bars

Sagem-Lucas system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Not available

Specified idle speed:

Bosch L3.1 system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

925 ± 25 rpm

Other systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

850 ± 50 rpm (not adjustable - controlled by ECU)

Idle mixture CO content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Less than 1.0 % (not adjustable- controlled by ECU)

Recommended fuel

Minimum octane rating:

TU3 (K1A), TU3A (K1G), XU92C (D2D), XU9J2 (D6A),
XU9J4 (D6C), XU52C (B2A) engines . . . . . . . . . . . . . . . . . . . . . . . . . .

97 RON leaded*

All other engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

95 RON unleaded (UK unleaded premium). Leaded fuel must not be
used on models with a catalytic converter

*It may be possible to use unleaded if the ignition is retarded by 3° - check with your Peugeot dealer.

Chapter 4 Part C: Fuel/exhaust systems -
multi-point fuel injection models

ACAV inlet system (16-valve models) -

general information, removal and refitting . . . . . . . . . . . . . . . . . . .19

Accelerator cable - removal, refitting and adjustment  . . . . . . . . . . . . .3
Accelerator pedal - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . .4
Air cleaner assembly and inlet ducts - removal and refitting  . . . . . . . .2
Air cleaner filter element renewal  . . . . . . . . . . . . . . . . . .See Chapter 1
Bosch L3.1-Jetronic system components -

removal, refitting and adjustments . . . . . . . . . . . . . . . . . . . . . . . . .14

Bosch LU2-Jetronic system components -

removal, refitting and adjustments . . . . . . . . . . . . . . . . . . . . . . . . .15

Bosch Motronic system components -

removal, refitting and adjustments . . . . . . . . . . . . . . . . . . . . . . . . .16

Electronic control unit - removal and refitting . . . . . . . . . . . . . . . . . .13
Exhaust manifold - removal and refitting . . . . . . . . . . . . . . . . . . . . . .20
Exhaust system check . . . . . . . . . . . . . . . . . . . . . . . . . . .See Chapter 1

Exhaust system - general information, removal and refitting  . . . . . . .21
Fuel filter renewal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .See Chapter 1
Fuel gauge sender unit - removal and refitting . . . . . . . . . . . . . . . . . . .9
Fuel injection system - depressurisation  . . . . . . . . . . . . . . . . . . . . . . .7
Fuel injection system - testing and adjustment  . . . . . . . . . . . . . . . . .11
Fuel injection systems - general information  . . . . . . . . . . . . . . . . . . . .6
Fuel pump - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Fuel tank - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
General information  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Idle speed and mixture adjustment  . . . . . . . . . . . . . . . . .See Chapter 1
Inlet manifold - removal and refitting  . . . . . . . . . . . . . . . . . . . . . . . . .18
Magneti Marelli system components -

removal, refitting and adjustments . . . . . . . . . . . . . . . . . . . . . . . . .17

Throttle housing - removal and refitting . . . . . . . . . . . . . . . . . . . . . . .12
Unleaded petrol - general information and usage . . . . . . . . . . . . . . . .5

4C•1

Easy, suitable for
novice with little
experience

Fairly easy, suitable
for beginner with
some experience

Fairly difficult,
suitable for competent
DIY mechanic

Difficult, suitable for
experienced DIY
mechanic

Very difficult,
suitable for expert
DIY or professional

Degrees of difficulty

Specifications

Contents

General information and
precautions

The fuel supply system consists of a fuel

tank (mounted under the rear of the car), with
an electric fuel pump either mounted
externally or internally in the tank, a fuel filter,
fuel feed and return lines. The fuel pump
supplies fuel to the fuel rail, which acts as a
reservoir for the four fuel injectors which inject
fuel into the inlet tracts. The fuel filter
incorporated in the feed line from the pump to
the fuel rail ensures that the fuel supplied to
the injectors is clean.

Refer to Section 6 for further information on

the operation of each fuel injection system,
and to Section 21 for information on the
exhaust system. Throughout this Section, it is
also occasionally necessary to identify
vehicles by their engine codes rather than by
engine capacity alone. Refer to the relevant
Part of Chapter 2 for further information on
engine code identification.

Note: Residual pressure will remain in the

fuel lines long after the vehicle was last used.
When disconnecting any fuel line, first
depressurise the fuel system as described in
Section 7.

Note: At the time of writing little information

was available for the Sagem-Lucas injection
system.

Air cleaner assembly and
inlet ducts - removal and
refitting

Removal

Early models and all models with air
cleaner located on left-hand side of
engine

1 Where applicable, disconnect the multi-
plug from the airflow meter (see illustration).
2 Loosen the clip on the upper air inlet duct.
3 Remove the cover and lift out the air filter.
On the square type housing it will be
necessary to release the clips first.
4 To remove the housing, release the lower
clips, disconnect the lower duct and lift out
the housing (see illustration).

Later models and all models with air
cleaner located over the engine

5 Slacken the retaining clip(s) and disconnect
the breather hose(s) from the side of the air
cleaner-to-throttle housing duct. Slacken the
duct retaining clips, then disconnect it from
the air cleaner and throttle housing, and
remove it from the vehicle. Where necessary,
recover the rubber sealing ring from the
throttle housing.
6 Release the two retaining clips, then
slacken and remove the two retaining screws
from the front of the cylinder head cover, and
remove the air cleaner element cover from the
head. Withdraw the air cleaner element.
7 To remove the inlet duct, undo the bolt
securing the rear section of the duct to the

end of the cylinder head, then slacken the
retaining clip and disconnect the duct from
the cylinder head cover. Undo the bolt
securing the front of the duct to the
crossmember and manoeuvre the duct out of
the engine compartment.

Refitting

8 Refitting is a reversal of removal, but clean
out the housing first.

Accelerator cable - removal,
refitting and adjustment

1 Refer to Chapter 4A, Section 7, substituting
“throttle housing” for all references to the
carburettor. Also refer to Chapter 4B, Section
4 (see illustrations). On models with
automatic transmission, once the accelerator
cable is correctly adjusted, check the
kickdown cable adjustment (Chapter 7B).

Accelerator pedal -
removal and refitting

Refer to Chapter 4A, Section 8.

Unleaded petrol -
general information and usage

Note: The information given in this Chapter is
correct at the time of writing. If updated

2.4 Removing the air cleaner housing

2.1 Disconnecting the airflow meter

multi-plug (Bosch L3.1-Jetronic)

Torque wrench settings

lbf ft

Inlet manifold:

TU engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

XU engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Exhaust manifold nuts:

TU engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

XU engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Exhaust system fasteners:

Front pipe-to-manifold nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Front pipe mounting bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Front pipe-to-intermediate pipe/catalytic converter nuts . . . . . . . . . .

Clamping ring nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4C•2 Fuel/exhaust systems - multi-point fuel injection models

Warning: Many of the
procedures in this Chapter
require the removal of fuel lines
and connections, which 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.

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.

The fuel recommended by Peugeot is given

in the Specifications Section of this Chapter,
followed by the equivalent petrol currently on
sale in the UK.

All multi-point injection models are

designed to run on fuel with a minimum
octane rating of 95 (RON). All models with a
catalytic converter must be run on unleaded
fuel only. Under no circumstances should
leaded fuel (UK “4-star”) be used, as this may
damage the converter.

Fuel injection systems -
general information

Note: On later models the fuel injection ECU
is of the “self-learning” type, meaning that as it
operates, it also monitors and stores the
settings which give optimum engine
performance under all operating conditions.
When the battery is disconnected, these
settings are lost and the ECU reverts to the
base settings programmed into its memory at
the factory. On restarting, this may lead to the
engine running/idling roughly for a short while,
until the ECU has re-learned the optimum
settings. This process is best accomplished by
taking the vehicle on a road test (for
approximately 15 minutes), covering all engine
speeds and loads, concentrating mainly in the
2500 to 3500 rpm region.

Bosch L3.1 (Jetronic) system

1 The Bosch L3.1 fuel injection system is of
the intermittent type operating under low
pressure. Fuel is drawn from the rear-
mounted fuel tank by an externally-mounted
fuel pump and delivered through an in-line
filter to the injectors. A pressure regulator
mounted on the outlet side of the fuel rail, and
connected by pipe to the inlet manifold to
sense vacuum, maintains a constant pressure
at the injectors according to the depression in
the inlet manifold, returning excess fuel to the
fuel tank.
2 A pulse damper on the inlet side of the fuel

rail damps out the pressure pulses caused by
the operation of the injectors.
3 The electronic control unit (ECU) and
airflow meter are mounted on the air filter
housing. The ECU uses signals from various
sensors to determine the opening period of
the injectors for any given engine operating
condition. The inputs are as follows.

a) Amount of air being drawn in by the

engine via the airflow meter.

b) Inlet air temperature via the thermistor

mounted in the airflow meter.

c) Engine speed and angular position via the

injection (coolant) thermistor.

d) Throttle position via the throttle switch

unit.

4 The injectors operate simultaneously,
spraying fuel onto the inlet side of the inlet
valves.
5 A supplementary air device is fitted to the
system to compensate for the extra fuel
required during cold start conditions.

Bosch LU2-Jetronic system

6 The principle of operation of the LU2-
Jetronic system is similar to that described for
the L3.1-Jetronic system but with the
following differences.

a) A single-barrel throttle body is fitted.
b) An oxygen sensor is fitted.
c) A catalytic converter is fitted.

7 The most significant difference is that the
LU2-Jetronic system incorporates an oxygen
sensor in the exhaust system, which enables
the electronic control unit to carry out fine
fuel/air mixture adjustment to allow the use of
a catalytic converter.

Bosch Motronic MP3.1 system

8 The principle of operation of the Motronic
MP3.1 system is similar to that described for
the L3.1-Jetronic system but with the
following differences.

a) The ECU controls the ignition system in

addition to the fuel injection system,
providing an integrated engine
management system.

b) A static (distributorless)ignition system is

used.

c) An inlet air temperature sensor and a

manifold absolute pressure (MAP) sensor
are used in place of the airflow meter.

d) An engine speed/position sensor is used

to provide information on engine speed
and crankshaft position.

Bosch Motronic M1.3 system

9 The principle of operation of the Motronic
M1.3 system is similar to that described for
the L3.1-Jetronic system but with the
following differences.

a) The ECU controls the ignition system and

the fuel injection system, providing an
integrated engine management system.

b) An engine speed/position sensor is used

to provide information on engine speed
and crankshaft position.

c) The ECU controls the idle speed under all

engine operating conditions, via an idle
speed control valve. No supplementary air
device is fitted.

d) An oxygen sensor is fitted to enable the

ECU to control the air/fuel mixture very
accurately, allowing the use of a catalytic
converter.

e) A knock sensor, mounted in the cylinder

block is used to detect the onset of
engine knock, or pre-ignition. This
enables the ECU to select the optimum
ignition advance for the prevailing engine
operating conditions without risk of
damage to the engine.

Bosch Motronic ML4.1 system

10 The principle of operation of the Motronic
ML4.1 system is similar to that described for
the L3.1-Jetronic system but with the
following differences.

a) The ECU incorporates a cold start

function and a fault memory.

b) The mixture adjustment by-pass screw is

replaced by an adjustment screw on the
throttle potentiometer.

c) The throttle housing has a double body.
d) Idle speed is maintained at a

predetermined level (regardless of load)
by an idle speed valve.

Bosch Motronic MP5.1 system

11 The Bosch Motronic MP5.1 engine
management (fuel injection/ignition) system
incorporates a closed-loop catalytic converter
and an evaporative emission control system,
and complies with the very latest emission
control standards. Refer to Chapter 5 for
detaisl on the ignition side of the system; the
fuel side of the system operates as follows.
12 The fuel pump (which is immersed in the
fuel tank) supplies fuel from the tank to the
fuel rail, via a filter mounted underneath the
rear of the vehicle. Fuel supply pressure is
controlled by the pressure regulator in the fuel
rail. When the optimum operating pressure of
the fuel system is exceeded, the regulator
allows excess fuel to return to the tank.
13 The electrical control system consists of
the ECU, along with the following sensors:

a) Throttle potentiometer - informs the ECU

of the throttle position, and the rate of
throttle opening/closing.

Fuel/exhaust systems - multi-point fuel injection models 4C•3

3.1b Disconnecting the accelerator cable

end fitting (Bosch L3.1 system)

3.1a Disconnecting accelerator cable from

the throttle quadrant (Bosch L3.1 system)

b) Coolant temperature sensor - informs the

ECU of engine temperature.

c) Inlet air temperature sensor - informs the

ECU of the temperature of the air passing
through the throttle housing.

d) Lambda sensor - informs the ECU of the

oxygen content of the exhaust gases
(explained in Part D of this Chapter).

e) Crankshaft sensor - informs the ECU of

crankshaft position and speed of rotation.

f) Manifold Absolute Pressure (MAP) sensor

- informs the ECU of the load on the
engine (expressed in terms of inlet
manifold vacuum).

g) Vehicle speed sensor - informs the ECU

of the vehicle speed.

14 All the above signals are analysed by the
ECU which selects the fuelling response
appropriate to those values. The ECU controls
the fuel injectors (varying the pulse width - the
length of time the injectors are held open - to
provide a richer or weaker mixture, as
appropriate). The mixture is constantly varied
by the ECU, to provide the best setting for
cranking, starting (with either a hot or cold
engine), warm-up, idle, cruising and
acceleration.
15 The ECU also has full control over the
engine idle speed, via an auxiliary air valve
which bypasses the throttle valve. When the
throttle valve is closed, the ECU controls the
opening of the valve, which in turn regulates
the amount of air entering the manifold, and
so controls the idle speed.
16 The ECU also controls the exhaust and
evaporative emission control systems, which
are described in Part D of this Chapter.
17 An electric heating element is fitted to the
throttle housing; the heater is supplied with
current by the ECU, and warms the throttle
housing on cold starts to prevent possible
icing of the throttle valve.
18 If there is an abnormality in any of the
readings obtained from either the coolant
temperature sensor, the inlet air temperature
sensor or the lambda sensor, the ECU enters
its back-up mode. In this event, it ignores the
abnormal sensor signal and assumes a pre-
programmed value which will allow the engine
to continue running (albeit at reduced
efficiency). If the ECU enters this back-up
mode, the warning light on the instrument
panel will come on, and the relevant fault
code will be stored in the ECU memory.
19 If the warning light comes on, the vehicle
should be taken to a Peugeot dealer at the
earliest opportunity. A complete test of the
engine management system can then be
carried out, using a special electronic
diagnostic test unit which is simply plugged
into the system’s diagnostic connector.

Magneti Marelli 8P system

20 The Magneti Marelli 8P engine
management (fuel injection/ignition) system is
very similar in operation to the Bosch MP5.1
system described above, apart from the idle
speed control system.

21 On the Magneti Marelli system, the idle
speed is controlled by the ECU via a stepper
motor fitted to the throttle housing. The motor
has a pushrod controlling the opening of an
air passage which bypasses the throttle valve.
When the throttle valve is closed, the ECU
controls the movement of the motor pushrod,
which regulates the amount of air which flows
through the throttle housing passage, so
controlling the idle speed. The bypass
passage is also used as an additional air
supply during cold starting.

Fuel injection system -
depressurisation

Note: Refer to the warning note in Section 1
before proceeding.

1 The fuel system referred to in this Section is
defined as the tank-mounted fuel pump, the
fuel filter, the fuel injectors, the fuel rail and
the pressure regulator, and the metal pipes
and flexible hoses of the fuel lines between
these components. All these contain fuel
which will be under pressure while the engine
is running, and/or while the ignition is
switched on. The pressure will remain for
some time after the ignition has been
switched off, and must be relieved in a
controlled fashion when any of these
components are disturbed for servicing work.
2 Disconnect the battery negative terminal.
3 Place a container beneath the connection/
union to be disconnected, and have a large
rag ready to soak up any escaping fuel not
being caught by the container.
4 Slowly loosen the connection or union nut
to avoid a sudden release of pressure, and
wrap the rag around the connection, to catch
any fuel spray. Once the pressure is released,
disconnect the fuel line. Plug the pipe ends, to
minimise fuel loss and prevent the entry of dirt
into the fuel system.

Fuel pump -
removal and refitting

Refer to Chapter 4B, Section 9.

Fuel gauge sender unit -
removal and refitting

Refer to Chapter 4A, Section 5. Where the

fuel pump is mounted externally there are no
fuel pipe connections to the sender unit.

10 Fuel tank -

removal and refitting

Refer to Chapter 4A, Section 6, noting that

it will be necessary to depressurise the fuel
system before the feed and return hoses are
disconnected (see Section 7). It will also be
necessary to disconnect the wiring connector
from the internal fuel pump before lowering
the tank out of position.

11 Fuel injection system -

testing and adjustment

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 cylinder compression pressures are
correct, the ignition timing is correct, 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.
On later models 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 carries a risk of
damaging the ECU.

Adjustment

Bosch L3.1 and MP3.1 systems

3 Before attempting to adjust the idle speed
or mixture (CO), ensure that the following
conditions are met.

a) Ignition system is in good condition and

correctly adjusted.

b) Air filter is clean.
c) Throttle initial positions correctly adjusted.
d) Throttle switch correctly adjusted.
e) Engine must be hot, the cooling fan

having cut in at least once, but the fan
must not be running during the actual
adjustment.

4 Idle speed is adjusted using the idle speed
adjustment screw on the throttle housing (see
illustration). Turn the screw clockwise to
decrease the idle speed, or anti-clockwise to
increase the speed.
5 To adjust the idle mixture, prise out the
tamperproof cap covering the mixture (CO)
adjustment screw on the airflow meter unit.

4C•4 Fuel/exhaust systems - multi-point fuel injection models

Warning: The following
procedure will merely relieve
the pressure in the fuel system -
remember that fuel will still be

present in the system components and
take precautions accordingly before
disconnecting any of them.

6 Connect an exhaust gas analyser to the
vehicle in accordance with the manufacturer’s
instructions.
7 Start the engine and allow it to idle. Turn
the mixture adjustment screw in or out to
obtain the specified CO content (see
illustration).
8 Re-adjust the idle speed as previously
described.
9 On completion, stop the engine, remove all
test equipment and fit a new tamperproof cap
to the screw.

Bosch ML4.1 system

10 The idle speed is non-adjustable. It is
controlled by the idle speed regulator valve.
11 To check the mixture (CO), first ensure
that the conditions in paragraph 3 are met.
12 Connect an exhaust gas analyser to the
vehicle in accordance with the manufacturer’s
instructions.
13 Remove the tamperproof cap from the
mixture adjustment screw on the airflow meter
housing.
14 Turn the screw clockwise to increase and
anti-clockwise to decrease CO content until
the specified CO level is obtained.
15 Remove all test equipment and fit a new
tamperproof plug to the screw.

Bosch LU2-Jetronic system

16 Idle speed is adjusted as described for
the Bosch L3.1 system (see illustration).

17 Idle mixture is not adjustable, and is
automatically regulated by the electronic
control unit according to signals provided by
the oxygen sensor.

Bosch Motronic M1.3 system

18 Idle speed is only adjustable on 8-valve
engines; on 16-valve engines it is controlled
by the ECU. On 8-valve engines use the
procedure given in paragraphs 3 and 4.
19 Adjustment of idle mixture is as given in
paragraphs 5 to 9.

MM8P, Sagem-Lucas 4GJ,
Bosch Motronic 5.1,
Bosch Motronic 3.2 systems

20 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. Neither the mixture adjustment
(exhaust gas CO level) nor the idle speed are
adjustable, and should either be incorrect, a
fault must be present in the fuel injection
system.

12 Throttle housing -

removal and refitting

Note: At the time or writing no information
was available for the Sagem-Lucas system.

Removal

1 Disconnect the battery negative terminal.

Bosch Jetronic system

2 Remove the airflow meter with reference to
Section 2.
3 Disconnect the accelerator cable from the
throttle housing.
4 Either drain the cooling system or clamp
the coolant hoses as close as possible to the
throttle housing, then disconnect the coolant
inlet hose (see illustration).
5 Disconnect the throttle switch wiring multi-
plug (see illustration).
6 Loosen the clip and detach the plastic duct
from the throttle housing (see illustration).
7 Disconnect the coolant return hose,
distributor vacuum hose and breather hose
from the throttle housing (see illustration).

Fuel/exhaust systems - multi-point fuel injection models 4C•5

11.16 Idle speed adjustment screw (2)

(LU2-Jetronic system)

12.7 Disconnect the coolant return (A),

distributor vacuum hose (B)

and breather hose (C)

12.6 Detach the plastic duct

12.5 Disconnecting the multi-plug

12.4 Disconnecting the coolant inlet hose

11.4 Adjusting the idle speed screw on the

Bosch L3.1 system

11.7 Mixture (CO ) adjustment screw on

the airflow meter (Bosch L3.1 system)

Content .. 15 16 17 18 ..