RENAULT MEGANE SCENIC 1995 Service Repair Manual

INJECTION
Special notes on semi-sequential injection
17
K7M engine
OPERATING PRINCIPLE
The K7M engine is fitted with semi-sequential injection.
Injection of fuel is carried out simultaneously to cylinders 1 - 4 and cylinders 2 - 3.
To do this, the two pairs of injectors are connected to two injection computer tracks:
- the injectors for cylinders 1 and 4 are connected to computer track 4 ,
- the injectors for cylinders 2 and 3 are connected to computer track 30 .
For each cylinder, there is one injection per revolution, i.e. two per cycle. These injections take place during
the compression and exhaust phases.
The injection computer uses the same system as that used to control the ignition coils for determining when
to control which injector. By analysing the signal from the flywheel, it knows the TDC point for cylinders 1 - 4
and cylinders 2 - 3 (see principle in section 17 "Ignition"). By counting the number of teeth, the engine phases
preceding TDC maybe determined.
17-17

INJECTION
Special notes on semi-sequential injection
17
K7M engine
cylinder 2compression expansion exhaust inletTDC
TDC
cylinder 3
exhaust inlet compression expansionTDC
cylinder 1
TDC TDC
inlet compression expansion exhaustTDC
cylinder 4expansion exhaust inlet compression
TDCTDCTDC
computer track
N° 4
12 V
0 V
computer track
N° 30
12 V
0 V
Ignition
1revolution 1revolution
1 cycle
injection of petrolTDC
17-18

INJECTION
Special notes on sequential injection
17
F3R engine
PRESENTATION
The F3R engine is fitted with sequential injection.
Injection of fuel is not carried out simultaneously
to all four cylinders as with conventional injection,
but cylinder after cylinder when they are at the
start of the inlet phase.
To do this, it is necessary for:
- each injector to be connected separately to
the computer (injector n° 1 is at the flywheel
end),
- the computer to know which cylinder is at the
inlet phase.
To determine the cylinder at the inlet phase, the
computer uses 2 sensors:
- the TDC sensor,
- the cylinder reference sensor.
The TDC sensor allows the computer to determine
the engine speed, and to know which cylinders
are at TDC:
- cylinders 1 and 4 at TDC,
- cylinders 2 and 3 at TDC.
The cylinder reference sensor allows the computer
to know which of the two cylinders at TDC is at
the start of the inlet phase.
DEFECT MODE IN THE CASE OF A FAULT WITH THE
CYLINDER REFERENCE SENSOR
The system remains in sequential injection. The
cycle 1 - 3 - 4 - 2 is retained.
When fuel is injected for the first time, or at the
beginning of the starting phase, the computer
decides arbitrarily to inject fuel to cylinder n° 1
when cylinders 1 and 4 are at TDC.
Two possibilities may then arise:
- the system is phased correctly,
- the system is out of phase by one revolution.
Operation of the engine is not greatly affected.
DESCRIPTION
The cylinder reference sensor (A) is located at the
end of the camshaft. It is mounted by three bolts
on to the cylinder head.
The sensor is opposite a long target of 180°. This is
mounted on the end of the camshaft.
If the target is located within the sensor air gap,
12 V is sent to the computer.
If the target is not in the sensor airgap, 0 V is sent
to the computer.
SENSOR OPERATING PRINCIPLE
The sensor is supplied with 12 Volts. The computer
sends it a 5 V feed on track 2.
Depending on the position of the target, the sen-
sor closes the circuit and earths this voltage (the
computer receives 0 V), or the sensor leaves the
circuit open (the computer receives 12 V).
99238R3
17-19

INJECTION
Special notes on sequential injection
17
F3R engine
PRINCIPLE FOR RECOGNISING THE CYLINDER AT THE INLET PHASE
Depending on the signal from the TDC sensor, the computer knows at what moment cylinders 1 and 4 are at
TDC and at what moment cylinders 2 and 3 are at TDC. (For further explanations refer to section 17
"Ignition").
Cylinders 1 and 4 are at TDC,
- if the signal from the cylinder reference sensor is 0 Volts, cylinder 4 is at the start of the inlet phase,
- if the signal from the cylinder reference sensor is 12 Volt, cylinder 1 is at the start of the inlet phase.
Cylinders 2 and 3 are at TDC,
- if the signal from the cylinder reference sensor is 0 Volts, cylinder 3 is at the start of the inlet phase,
- if the signal from the cylinder reference sensor is 12 Volt, cylinder 2 is at the start of the inlet phase.
LOGIC
Signal from cylinder
reference sensorCylinder at start of inlet phase
12 Volt 1
0 Volts 4
12 Volt 2
0 Volts 3Cylinder at TDC
1 - 4
2 - 3
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INJECTION
Special notes on sequential injection
17
F3R engine
A 1 rotation of the crankshaft
B 1 rotation of the camshaft
C TDC 1 - 4
D TDC 2 - 3
1 Cylinder 1 at inlet
2 Cylinder 2 at inlet
3 Cylinder 3 at inlet
4 Cylinder 4 at inlet
5 Gap in flywheel
684° or 14 teeth
7 30 teeth
X Flywheel target
Y Camshaft target
Z Voltage from cylinder reference sensor
NOTE : All values are given in TDC degrees.
98406R1
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INJECTION
Special notes on sequential injection
17
F3R engine
1.REMOVING THE CYLINDER REFERENCE
SENSOR
Disconnect the sensor
Remove:
- the cylinder reference sensor (A) (one bolt),
- the cover (B) (three bolts).
Target (C) is secured on the end of the camshaft
by a spring ring.
To release the target from the camshaft:
• Rest a copper hammer behind the target.
• Use a mallet to tap the hammer gently.
• Remove the target (C) and the plastic
protective cover (D).
IMPORTANT : the order of operations described
below MUST be observed. Not following the
method could cause incorrect operation and / or
damage to the sensor.
2.REFITTING THE CYLINDER REFERENCE SENSOR
Refit :
- the sensor to the cover, push it upwards and
tighten to a torque of 0.15 daN.m,
- the protective plastic cover,
- the target (this has a foolproofing device.
Check its position before fitting to the end of
the camshaft),
- the cover with the sensor. Tighten the three
cover bolts to a torque of 1 daN.m.3.
ADJUSTING THE SENSOR / TARGET GAP
Slacken the bolt mounting the sensor without
touching the sensor then retighten it to a torque
of 0.8 daN.m.
By slackening the bolt the sensor is released. A
spring in the cover pushes the sensor against the
target.
When the bolt is tightened the sensor is secured. It
has two small plastic pips which touch the target.
These pips wear as the engine turns. There is no
longer contact between the two components and
the gap is set.
17-22

INJECTION
Special notes on sequential injection
17
F3R engine
CYLINDER REFERENCE SENSOR CONNECTIONS
TRACK ALLOCATION
1 Earth
2 Information to injection computer on track 42
3 +after ignition
1REMOVAL2REFITTING
DI1701DI1702
DI1703
3ADJUSTMENT
17-23

INJECTION
Injection fault warning light
17
PRINCIPLE FOR ILLUMINATION OF THE INJECTION FAULT WARNING LIGHT ON THE INSTRUMENT PANEL
• Vehicle without engine immobiliser system
When the ignition is turned on, the warning light illuminates for 3 seconds then extinguishes.
• Vehicle with engine immobiliser system deactivated
When the ignition is turned on, the warning light illuminates for 3 seconds then extinguishes.
When the doors are unlocked, the red immobiliser warning light, which was previously flashing, extin-
guishes. When the ignition is turned on, it illuminates for 3 seconds then extinguishes.
• Vehicle with engine immobiliser system activated
When the ignition is turned on, the computer does not identify the code and the vehicle cannot be star-
ted. The injection warning light illuminates for 3 seconds then extinguishes.
Before the ignition is turned on, the red immobiliser warning light flashes. When the ignition is turned
on, this light flashes twice as fast.
If a fault in the immobiliser system is detected when the engine is running, the injection warning light
will flash in the engine speed range from idle speed to 1 500 rpm approximately.
• Fault with an injection system component
Faults in the following components cause the warning light to illuminate:
- absolute pressure sensor,
- throttle position potentiometer,
- injectors,
- idle speed regulation stepping motor (K7M engine),
- idle speed regulation valve (F3R engine),
- no vehicle speed information when the vehicle is moving,
- EGR solenoid valve (K7M 703 engine),
- automatic transmission computer → injection computer (F3R - K7M engines).
17-24

INJECTION
Engine immobiliser function
17
This vehicle is fitted with a 2nd generation engine immobiliser system.
REPLACING THE INJECTION COMPUTER
The computers are supplied uncoded but are capable of being programmed with a code.
When replacing the computer, the vehicle code must be programmed in and then check that the immobiliser
system is operational.
To do this, carry out the following operations:
•Vehicle fitted with a PLIP engine immobiliser system
- Lock and unlock the doors using the PLIP.
- Turn the ignition on for a few seconds.
- Lock the doors using the PLIP, the immobiliser function is operational.
•Vehicle fitted with a coded key engine immobiliser system
Turn the ignition on for a few seconds then turn it off again.
CHECKING THE IMMOBILISER FUNCTION
•Vehicle fitted with a PLIP engine immobiliser system
- Turn the ignition off, lock the doors from inside the vehicle using the PLIP. The red immobiliser
warning light should flash.
- Turn the ignition on, The red immobiliser warning light should flash twice as fast.
•Vehicle fitted with a coded key engine immobiliser system
Remove the key from the ignition switch, after 10 seconds the red immobiliser warning light should flash.
TESTING AN UNCODED INJECTION COMPUTER FROM STOCK OR FROM A VEHICLE NOT FITTED WITH AN
IMMOBILISER SYSTEM
To avoid coding the injection computer before the test, it is vital to cut the + 12 V before ignition feed to the
immobiliser system. Remove the passenger compartment connection unit fuse (F39) (for more details, refer
to section 82).
NOTE : if the injection computer has been coded by mistake, a method exists for decoding it (refer to section
82).
SPECIAL NOTES
Using the XR25 it is possible to see if the injection computer is coded. The computer is uncoded if bargraph 2
right hand side is illuminated and if *22 = 2 DEF
A CODED COMPUTER FITTED TO A VEHICLE WITH AN ENGINE IMMOBILISER MAY NOT BE USED FOR TESTING
ANOTHER VEHICLE, REGARDLESS OF WHETHER THIS VEHICLE HAS AN ENGINE IMMOBILISER OR NOT.
17-25

INJECTION
Computer configuration as a function of the gearbox type17
F3R engine
The display shows:
CONFIGURING THE COMPUTER DEPENDING ON GEARBOX TYPE (MANUAL OR AUTOMATIC)
Each time the injection computer is replaced, the gearbox type for the vehicle must be programmed (manual
or automatic). The computer is designed to operate with both these types of gearbox.
Procedure for configuring the computer:
Connect the XR25
ISO selector on S8
Turn the ignition on
Enter D13 then
For a vehicle fitted with a manual gearbox:
Enter G60*
For a vehicle fitted with an automatic transmission:
Enter G50*
If the configuration has not been programmed
After programming the configuration, turn the ignition off to store it in the memory. Memorisation is effec-
tive after the ignition has been turned off, once the computer has left the monitoring mode.
The monitoring mode varies from 30 seconds to 13 minutes.
then once the configuration is
complete
17-26