1995 RENAULT MEGANE SCENIC Fuel

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 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
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

INJECTION
Adaptive richness correction
17
Special notes for the E7J engine
A road test should be carried out after which the engine should be allowed to idle for a few minutes. The va-
lues for #30 and #31 should have changed.
During the road test, stabilise the engine speed for a few moments between 2 000 rpm and 4 400 rpm and the
manifold pressure between 400 and 700 mbars.
Condition #31 : if engine speed < 1 000 rpm and if the manifold pressure < 450 mbars, #31 should be mo-
dified.
INTERPRETING VALUES GATHERED AFTER A ROAD TEST
If there is a lack of fuel (injectors dirty, fuel pressure and flow too low...), richness regulation # 35 increases to
obtain the richness as close as possible to richness 1 and adaptive correction # 30 and # 31 increases until the
richness correction returns to oscillate around 128.
If there is an excess of fuel, the situation is reversed:
Richness regulation # 35 reduces and adaptive correction # 30 and # 31 also reduces to recentre the richness
correction (# 35) around 128.
NOTE: the analysis which may be made using # 31 remains difficult since this correction mainly operates for
idle speed and low loads and is also very sensitive.
Hasty conclusions should not therefore be drawn from this gate value, rather the position of # 30 should be
examined.
The information from these two gates gives an idea about the engine operation richness, and may be used as
a guide for fault finding. For them to be of use during fault finding, conclusions may only be drawn if the va-
lues are at the minimum or maximum correction thresholds, and if both values have drifted in the same direc-
tion.
IMPORTANT : # 30 and # 31 should only be examined and analysed after a customer complaint, an opera-
ting fault and if they are at the threshold with the value for # 35 also offset (# 35 varies above 175 or be-
low 80).
17-38

INJECTION
Operating wiring diagram
17
KEY TO OPERATIONAL WIRING DIAGRAMS (E7J, F3R, K7M)
COMPONENT NO DESCRIPTION
109
119
120
146
147
149
193 to 196
218
222
224
225
228
236
238
242
244
247
250
272
310
319
341
371
398
437
565
597
645
649
663
664
679
746
772
777
927
MF
MHOn board computer
Automatic transmission computer
Injection computer
Pinking sensor (located under the inlet manifold for E7J engine)
Absolute pressure sensor
TDC sensor
Injectors
Fuel pump
Throttle position potentiometer
Power assisted steering pressostat
Diagnostic socket
Idle speed regulation micromotor
Fuel pump relay (in engine fuse box)
Injection feed locking relay
Oxygen sensor
Coolant temperature sensor
Instrument panel
Vehicle speed sensor
Air temperature sensor
Ignition power module
Air conditioning control panel
Idle speed regulation solenoid valve
Fuel vapour recirculation solenoid valve
Exhaust gas recirculation solenoid valve (EGR)
Throttle body heater (under throttle body)
Throttle body assembly
Engine fuse box
Passenger compartment connection unit
Idle speed regulation stepping motor
Dual ignition coil n°1 (cylinders 1 and 4)
Dual ignition coil n° 2 (cylinders 2 and 3)
Radio anti-interference condenser
Cylinder reference sensor
Heater relay (in engine fuse box)
Power fuse board (near battery)
Inertia switch
Rear right hand electrical earth
Engine electrical earth (located on the cylinder block between the starter and the al-
ternator for the E7J engine)
17-39

INJECTION
Operating wiring diagram
17
TrackALLOCATION
25Not used
26Not used
27Not used
28Command for coil for cylinders 1 and 4
29Command for coil for cylinders 2 and 3
30Command for injector n° 1 and n° 4 via earth (n° 1 flywheel end)
31Pinking sensor screened cable
32+12 V before ignition
33TDC sensor signal (track B)
34TDC sensor signal (track A)
35Stepping motor command (0 - 12 V)
36Stepping motor command (0 - 12 V)
37Immobiliser coded line input
38Uni-directional diagnostic line L for entry into diagnostic mode only
(looking for computer)
39Not used
40Stepping motor command (0 - 12 V)
41Throttle angle information for automatic transmission computer
42RCO control (sequential earth period for canister bleed solenoid valve RCO)
43Command for injection fault warning light on instrument panel
44Common earth for pinking sensor and coolant temperature sensor and absolute pressure sensor
45+ 5 V feed for absolute pressure sensor and throttle position potentiometer
46Common earth for air temperature sensor and throttle position potentiometer
47Not used
48Command (via earth) for fuel pump relay and engine speed information
49Not used
K7M engine
17-45

INJECTION
Operating wiring diagram
17
TrackALLOCATION
50Fuel flow information for on board computer
51Air conditioning compressor clutch operation prevention command
(0 V → authorisation ; 12 V → prevention)
52Monitoring of injector feed and fuel pump feed from relay (236)
53Not used
54Not used
55Not used
K7M engine
17-46

INJECTION
Operating wiring diagram
17
COMPUTER TRACK ALLOCATION
TrackALLOCATION
1Not used
2Power earth n° 1
3Power earth n° 2
4Command for injector n° 3 via earth
5Heated windscreen information (0 - 12 V)
6Air conditioning on - off information and request for compressor operation authorisation
(0 - 12 V)
7Park / Neutral / torque reduction information (0 - 5 V) (F3R 751)
8Pinking sensor signal
9Not used
10Not used
11Bi-directional diagnostic line K used for entry into fault finding mode
(looking for computer), emission of diagnostic signals from computer, application of command
modes (G..*), erasing the memory (G0**)
and ending fault finding (G13*)
12Vehicle speed information
13Fuel flow information for on board computer
14Not used
15Coolant temperature sensor information
16Manifold pressure information transcribed by absolute pressure sensor
17Voltage information from oxygen sensor
18Oxygen sensor earth
19Throttle position potentiometer information
20Air temperature sensor information
21Not used
22Not used
23Not used
24+ 12 V after ignition
F3R engine
17-48