RENAULT MEGANE SCENIC 1995 Service Repair Manual

INJECTION
Computer configuration as a function of the gearbox type17
F3R engine
To check that storing has been correctly carried out, turn the ignition on using fault finding fiche n° 27, bar-
graph 20 LH side should be extinguished, bargraph 19 RH or LH side should be illuminated.
There is a method for configuring the computer which does not require the use of the XR25. To do this:
- turn the ignition on,
- start the engine,
- accelerate the engine to a speed greater than 2500 rpmfor 10 seconds,
- turn the ignition off,
- turn the ignition on again and start the engine,
- accelerate the engine to a speed greater than 2500 rpm for 10 seconds,
- turn the ignition off.
The memorisation procedure is the same as that described previously.
NOTE : the configuration procedure using the XR25 may be used to reconfigure an incorrectly configured
computer (automatic transmission instead of manual gearbox). The procedure which does not use the XR25
will however only work for an unconfigured blank injection computer from stock.
17-27

INJECTION
Injection strategy / Automatic transmission
17
AUTOMATIC TRANSMISSION COMPUTER CONNECTION TO INJECTION COMPUTER
"Park"/"Neutral" position and torque reduction information.
These two items of information are sent on one track of the injection computer.
Signal transmitted
5 V
0 VPosition P/NChange to "drive"
Torque reduction changing down
Torque reduction changing up
1.In the "Park" or "Neutral" position, you can check whether the voltage, measured using a voltmeter
between track 7 and earth is actually approximately5 V.
As soon as the "drive" (or "other") position is reached, the voltage drops to approximately 0.
2.From the "drive" position and while driving, the automatic transmission computer sends:
- a long pulse for changing up a gear,
- two short pulses for changing down a gear.
The injection computer, in both cases, to smooth the gear change, retards the advance by 25° compared
to the initial advance, for the complete period of torque reduction if the vehicle speed is greater than 6
mph (10 km/h).
The advance returns to the initial setting:
- at once for changing up a gear,
- progressively for changing down a gear.1
2 Position "drive"
Nominal
advance
- 25°
17-28

INJECTION
Injection strategy / air conditioning
17
AIR CONDITIONING / INJECTION COMPUTER CONNECTION
The electrical connection:
- from the air conditioning computer to the injection computer is by one wire. This track only transmits the
information that the air conditioning is operating. The injection computer deduces that the air
conditioning has been selected:
track 6 F3R engine
track 5 K7M engine
track 34 E7J engine
- from the injection computer to the air conditioning computer is by one wire. This track transmits the
compressor operation authorisation and prevention information :
track 51 F3R - K7M engines
track 20 E7J engine
PROGRAMMING FOR OPERATION OF THE COMPRESSOR
During certain operating phases, the injection computer prevents operation of the compressor.
Starting the engine
The compressor is prevented from operating for 10 seconds after the engine has been started.
Thermal protection
The compressor clutch is prevented from engaging if the coolant temperature is greater than or equal to :
- + 115°C (F3R and E7J engines)
- + 120°C (K7M engine)
Over-revving protection
The compressor may not operate if the engine speed is greater than :
- 6 000 rpm (F3R engine),
- 5 600 rpm (K7M engine),
- 5 400 rpm (E7J engine).
OPERATING PRINCIPLE
1.Idle speed regulation.
2.Air conditioning operation information becomes ON for the first time since the ignition was turned on.
The driver must select air conditioning from the control panel.
The idle speed is increased to:
F3R engine 900 rpm
K7M engine 850 rpm
E7J engine 900 rpm
The injection computer prevents the compressor from operating to assist the increase in idle speed.
3.2 to 5 seconds after receiving the information for air conditioning operation ON, the computer authorises
operation of the compressor and increases the idle speed regulation solenoid valve percentage opening.
The idle speed does not increase.
17-29

INJECTION
Injection strategy / air conditioning
17
4.Air conditioning operation information becomes OFF, the injection computer, anticipating the drop in
load due to the releasing of the compressor clutch, reduces the percentage opening of the idle speed
regulation solenoid valve then authorises the release of the compressor clutch and transmits the clutch
feed authorisation information OFF. The engine runs at fast idle speed.
(If the air conditioning computer has not received the compressor cut-out authorisation 2 seconds after
transmitting the air conditioning operation information OFF, it cuts the compressor itself).
5.Following prevention of compressor operation by the injection computer (clutch feed authorisation OFF),
the injection computer anticipates the drop in load due to the release of the clutch and reduces the per-
centage opening of the idle speed regulation solenoid valve. The compressor clutch is released by the air
conditioning computer.
6.Air conditioning operation information becomes OFF, the operation is similar to that described in point
4.
The engine is running at fast idle speed. To return to normal idle speed, the computer must detect that
the driver has turned the air conditioning off at the control panel. It deduces this state from the air
conditioning operation information if it is OFF for longer than :
- 15 seconds for K7M and E7J engines,
- 40 seconds for F3R engine,
shown by the letter X on the next page.
17-30

X
INJECTION
Injection strategy / air conditioning
17
(rpm)
Idle
speed(% opening)
Idle speed
regulation
valve
(time)
(time)
12346
OFF
(12V)
fast
nominalON
(0V)
353
AC ON
running (12 V)
OFF
(0 V)
Compressor
status
Clutch
authorisation
by
injection
computer
2 to 5 s Engaged Released
17-31

INJECTION
Idle speed correction
17
POWER ASSISTED STEERING PRESSOSTAT - INJECTION COMPUTER CONNECTION (K7M and E7J engines)
The injection computer receives information from the power assisted steering pressostat. This depends on the
pressure in the hydraulic circuit. The higher the pressure, the more energy is used by the power assisted
steering pump.
The injection computer, to compensate for this energy use, increases the percentage opening of the idle
speed regulation stepping motor for the K7M engine or adjusts the idle speed micromotor for the E7J
engine.
The information is received on track 13 (K7M engine) and track 8 (E7J engine) on the injection computer.
Pressostat closed, the computer receives an earth. The idle speed is adjusted to 820 rpmfor the K7M engine
and 825 rpm for the E7J engine.
IDLE SPEED CORRECTION DEPENDING ON THE BATTERY VOLTAGE (F3R engine)
This correction compensates for the drop in voltage due to operation of consumers when the battery is poorly
charged. To do this, the idle speed is increased, allowing the alternator to rotate more and consequently
increase the charging voltage.
The lower the voltage, the greater the degree of correction. Correction of the engine speed is therefore
variable. It begins when the voltage drops to below 12.7 Volts. Correction begins at the nominal engine
speed and may reach a maximum of 910 rpm.
IDLE SPEED CORRECTION DEPENDING ON HEATED WINDSCREEN INFORMATION
The E7J engine has no heated windscreen.
If the heated windscreen function is selected, the computer receives + 12 V information :
on track 6 for K7M engines
on track 5 for F3R engines.
If the coolant temperature is less than 60°C, the idle speed is set to :
- 1 000 rpm (F3R engine)
- 850 rpm (K7M engine)
17-32

INJECTION
Idle speed adaptive correction
17
PRINCIPLE ( K7M and F3R engines)
The E7J engine has no idle speed adaptive correction and no #12 function.
Under normal warm engine operating conditions, the RCO idle speed value using #12 varies between an up-
per and a lower value to obtain the nominal idle speed.
If the engine operating conditions are different (running in, engine contaminated...) the RCO idle speed va-
lue may be situated close to the upper or lower value.
Adaptive correction (#21) for the RCO idle speed (#12) allows compensation to be made for slow variations
in the engine’s air requirements, in order to recentre the RCO value (#12) to a nominal average value.
This correction is only operational if the coolant temperature is greater than 80°C, 20 seconds after starting
the engine and if the engine is in the nominal idle speed regulation phase.
RCO IDLE SPEED VALUES AND ADAPTIVE CORRECTION
Engine
F3R 750Engine
F3R 751Engine
K7M 702Engine
K7M 703Engine
K7M 720
Nominal idle
speed (#06)X = 770 rpm. X = 770 rpm. X = 720 rpm.X = 750 rpm.
in P and NX = 720 rpm.
R.C.O. idle speed
(#12)20 %≤X≤40 % 18 %≤X≤38 % 6 %≤X≤15 %10 %≤X≤20 %
in D
6 %≤X≤15 %
in P and N4 %≤X≤14 %
Adaptive idle
speed
(#21)Threshold:
- min : - 8.6 %
- max : +6.2 %Threshold:
- min : - 8.6 %
- max : +6.2 %Threshold:
- min : - 2.4 %
- max : +6.2 %Threshold:
- min : - 2.4 %
- max : +6.2 %Threshold:
- min : - 2.4 %
- max : +6.2 %
INTERPRETATION OF THE GATE VALUES
If there is an excess of air (air leak, throttle stop incorrectly set...) the idle speed increases, the RCO idle speed
value for #12 decreases to return to the nominal idle speed; the RCO idle speed adaptive correction value for
#21 reduces to recentre the RCO idle speed for #12.
If there is a lack of air (pollution, etc.), the strategy is reversed:
The RCO idle speed for #12 increases and adaptive correction for #21 also increases, in order to recentre #12
to a nominal average value.
IMPORTANT : after erasing the computer memory (disconnecting the battery), the engine must be allowed to
run at idle speed before returning the vehicle to the customer so that the adaptive correction may correctly
reset itself. Minimum threshold for the F3R engine 750 (- 8.6 %) : this value is taken from the definitive setting. The first
versions to be marketed have a threshold of - 6.2 %.
17-33

OXYGEN SENSOR VOLTAGE (#05)
Reading #05 on the XR25 : the value read is the voltage sent to the computer by the oxygen sensor; it is ex-
pressed in Volts (the value actually varies between 0 and 1 000 millivolts).
When the engine is in the loop phase, the voltage value should oscillate rapidly and should be between
50±50 mV (lean mixture) and 850 ± 50 mV (rich mixture) and vice versa.
The smaller the gap between the upper and lower oscillating values, the poorer the information from the
sensor (the gap is usually at least 500 mV).
RICHNESS CORRECTION (#35)
The value given under # 35 on the XR25 represents the average value of richness corrections made by the
computer depending on the richness of the burnt mixture as seen by the oxygen sensor (the oxygen sensor ac-
tually analyses the oxygen content of the exhaust gases directly from the richness of the burnt mixture).
The richness correction has a centre point of 128 with thresholds of 0 and 255 (experience has shown that un-
der normal operating conditions # 35 is located close to 128 with only a small amount of variation).
- Value less than 128 : request for mixture to be made leaner
- Value greater than 128 : request for mixture to be made richer
ENTRY INTO RICHNESS REGULATION MODE
Loop phase
Richness regulation begins after the timed starting period :
- for no load if the coolant temperature has reached:
•25°C for E7J engines,
•40°C for K7M engines,
•35°C for F3R engines.
- outside no load conditions if the coolant temperature is greater than :
•+ 20°C for K7M engines,
•+ 15°C for F3R engines,
there is no coolant temperature condition for E7J engines.
The timed starting period is dependent on the coolant temperature:
-at20°C it is a maximum of :
•45 seconds for E7J engines,
•1 minute for K7M engines,
•2 minutes for F3R engines,
-at80°C it is a maximum of :
•9 seconds for E7J engines,
•16 seconds for K7M engines,
•1 minute for F3R engines.
if richness regulation has not yet started,#35 = 128
INJECTION
Richness regulation
17
17-34

INJECTION
Richness regulation
17
Non-loop mode
When richness regulation is occurring, the operating phases when the computer ignores the voltage in-
formation from the oxygen sensor are:
- Full load: #35 = variable and greater than 128
- Sharp acceleration: #35 = variable and greater than 128
- Sharp deceleration with no load information (injection cut) : #35 = 128
- Oxygen sensor fault: #35 = 128
DEFECT MODE IN THE EVENT OF AN OXYGEN SENSOR FAULT
If the voltage from the oxygen sensor is incorrect (# 05 varies only slightly or not at all) during richness regu-
lation, the computer will only enter defect mode (# 35 = 128) if the fault has been present for 3 to 5 minutes.
The fault will be memorised in this case only.
If an oxygen sensor fault is present and recognised and if the fault has already been stored, the system enters
the open loop mode directly (# 35 = 128).
17-35

INJECTION
Adaptive richness correction
17
PRINCIPLE
In the loop mode (see section 17 "Richness regulation"), richness regulation (# 35), corrects the injection ti-
ming to give fuel metering which is as close as possible to richness 1. The correction value is close to 128, with
limit values of 0 and 255.
Variations may affect the components of the injection system and the correction may drift towards 0 or 255,
to ensure richness 1 is obtained.
Adaptive correction allows the injection mapping to be adjusted to recentre the richness regulation to 128
and to ensure a constant authority of correction to make the mixture leaner or richer.
Adaptive correction to richness regulation has two parts:
- Adaptive correction for average and high engine loads (#30)
- Adaptive correction for idle speed and low engine loads (#31).
Adaptive corrections take 128 as the average value after initialisation (erasing the memory ) and have the
following threshold values:
F3R engine K7M 702/703 engine K7M 720 engine E7J engine
82 ≤ #30 ≤ 224 0 ≤ #30 ≤ 208 0 ≤ #30 ≤ 208 112 ≤ #30 ≤ 160
32 ≤ #31 ≤ 224 104 ≤ #31 ≤ 255 100 ≤ #31 ≤ 255 104 ≤ #31 ≤ 160
Adaptive correction only takes place when the engine is warm, in the loop phase (#35 variable) and for a
specified manifold pressure range.
The engine must have operated in the loop mode for several pressure zones in order that adaptive correc-
tion begins to change to compensate for the variations in engine operating richness.
Following reinitialisation of the computer (return to 128 for # 30 and # 31) a special road test must therefore
be carried out.
17-36