2011 RENAULT SCENIC fuel pressure

13B-6V4 MR-372-J84-13B000$010.mif
DIESEL INJECTION
Fault finding – Introduction13B
DDCR INJECTION
Vdiag No.: 44, 48
You will always be asked for this log:
• when requesting technical assistance from the Techline,
• when requesting approval before replacing parts for which approval is compulsory,
• to be attached to monitored parts for which reimbursement is requested. The log is needed for warranty
reimbursement, and enables better analysis of the parts removed.
6. SAFETY INSTRUCTIONS
Safety rules must be observed during any work on a component to prevent any material damage or personal injury:
– check the battery voltage to avoid incorrect operation of computer functions,
– use the proper tools.
7. CLEANLINESS INSTRUCTIONS WHICH MUST BE FOLLOWED WHEN WORKING ON THE HIGH-
PRESSURE DIRECT INJECTION SYSTEM
Risks relating to contamination:
The high pressure direct injection system is highly sensitive to contamination. The risks associated with
contamination are:
– damage to or destruction of the high pressure injection system,
– components jamming,
– a component leaking.
All After-Sales operations must be performed under very clean conditions. This means that no impurities
(particles a few microns in size) should penetrate the system during dismantling.
The cleanliness principle must be applied from the filter to the injectors.
What are the sources of contamination?
– metal or plastic swarf,
– paint,
– fibres from cardboard, brushes, paper, clothing and cloth.
– foreign bodies such as hair,
– ambient air,
–etc.WARNING
BEFORE CARRYING OUT ANY WORK ON THE INJECTION SYSTEM, CHECK WITH THE DIAGNOSTIC
TOOL:
– that the rail is depressurised,
– that the fuel temperature is not too high.
IMPORTANT
Cleaning the engine using a high pressure washer is prohibited because of the risk of damaging connections. In
addition, moisture may collect in the connectors and create electrical connection faults.

13B-8V4 MR-372-J84-13B000$020.mif
13B
DDCR INJECTION
Vdiag No.: 44, 48
System outline
The DDCR injection system used on the K9 engine is an electronically managed high pressure injection system.
The fuel is compressed by a high pressure pump then stored in a rail that feeds the injectors. Injection occurs when
a current pulse is applied to the injector holders. The injected flow is proportional to the rail pressure and to
the applied pulse length, and the start of injection is phased with the start of the pulse.
The circuit comprises two subsystems, which are distinguished by the fuel pressure level.
– The low pressure system includes the tank, diesel fuel filter, transfer pump and injector holder return pipes.
– The high pressure circuit contains the high pressure pump, the rail, the injector holders and the high pressure tubes.
Finally, there are a certain number of sensors and regulating actuators for controlling and monitoring the entire
system.
Functions provided
Function: Fuel supply management (timing, flow and pressure).
Quantity of fuel injected and injection timing adjustment
The injection checking parameters are the quantities to be injected and their respective timing. These are calculated
by the computer using signals from the following sensors:
• Engine speed (Crankshaft + Cam for synchronisation)
• Accelerator pedal
• Turbocharging pressure and air temperature (Turbocharger pressure)
• Coolant temperature
• Air temperature
• Air load (Flow and Pressure)
• Rail pressure
• Flowmeter
• Turbocharging solenoid valve
The quantities to be injected and their respective timing are converted into:
• a reference tooth
• the time between this tooth and the start of the pulse
• the time for which the supply to the injector holder is on
An electrical current (pulse) is sent to each injector holder according to previously calculated data. The system
makes one or two injections (1 pilot injection, 1 main injection). The general principle is to calculate an overall
injected flow which will then be divided into a main injection flow and a pilot injection flow, to help the combustion
process work properly and to reduce pollutant emissions.
An accelerometer is used to monitor some of the fuel injection deviation. This has several roles:
• Protecting the engine by detecting injection leaks (disabled on the basic vehicle).
• Checking the pilot quantity by measuring deviation and dispersion
• By changing both the duration and timing of the injection, the quantity of fuel injected and the mixture ignition timing
can be adjusted.
DIESEL INJECTION
Fault finding – System operation

13B-9V4 MR-372-J84-13B000$020.mif
DIESEL INJECTION
Fault finding – System operation13B
DDCR INJECTION
Vdiag No.: 44, 48
Rail pressure check
The quality of combustion is influenced by the size of the atomised droplets in the cylinder. In the combustion
chamber, smaller fuel droplets will have time to burn fully, and will not produce smoke or unburned particles. To
meet the pollution requirements, the droplet size, and therefore the size of the injection holes, must be reduced.
With smaller holes, less fuel will be able to be introduced at a given pressure, which limits the power. To handle this
drawback, the injected fuel flow has to be increased, which means a pressure increase (and more apertures on the
injector nozzles). For the DDCR injection system, the pressure reaches 1400 bar in the rail, and must be constantly
regulated. The measuring circuit consists of an active pressure sensor on the rail connected to an analogue port on
the computer.
The High Pressure pump is supplied at low pressure (5bar) by a built-in transfer pump. This pump supplies the rail.
The rail filling pressure is controlled by the filling valve (IMV) and the discharge pressure is controlled by the injector
valves. This compensates for pressure drops. The filling actuator enables the high pressure pump to supply just
the exact quantity of diesel fuel required to maintain the rail pressure. This mechanism minimises the heat
generated and improves engine output.
In order to discharge the rail using the injector valves, the valves are actuated by short electrical pulses which are:
– short enough not to open the injector (and pass through the return circuit from the injectors),
– long enough to open the valves and discharge the rail.
The fuel surplus is sent back to the fuel filter or the tank, according to its flow. If there is no IMV control, the rail
pressure is limited by a discharge valve fitted on the pump.
Idling speed regulation
The computer handles the calculation of idling speed. This has to take account of the instantaneous power level to
be supplied, according to the following factors:
– Engine coolant temperature
– Gear engaged
– Battery charging
– Electrical consumers (Heating elements, Air conditioning, Fan assembly, Heated windscreen, etc.) active or
inactive
Individual injector correction (C2I)
The DDCR system injectors must be calibrated with corrective values to adjust their flow precisely. Each injector is
calibrated for different pressures on a test bench, and its specifications are shown on a label attached to the body of
the injector holders. These individual correction values are then written to the computer EEPROM, which can then
actuate the injectors by taking into account their manufacturing dispersion.

13B-10V4 MR-372-J84-13B000$020.mif
DIESEL INJECTION
Fault finding – System operation13B
DDCR INJECTION
Vdiag No.: 44, 48
Measuring the angular position (Cylinder reference sensor)
The angular position is measured using a magneto-inductive sensor triggered by machined teeth on the engine
flywheel. This flywheel has 60 teeth separated by six degrees, minus 2 missing teeth that form a notch.
A second sensor (Hall effect), activated by a machined tooth on the high pressure pump drive pulley
(synchronised with the camshaft), which rotates at half the engine speed, supplies a signal showing the progress of
the injection cycle. By comparing the signals from these two sensors, the computer's APS module (Angular Position
Subsystem) can supply the entire system with the synchronisation factors, namely: the angular position of
the flywheel, the engine speed, the number of the active injector, and the injection cycle timing. This module also
supplies the system with the engine speed signal.
Flow capacity function (VLC)
Because of the combination of several parameters such as the diesel fuel temperature, part wear, clogging of the
diesel filter, etc., the system may reach its limit during its service life. If this happens, the rail pressure cannot be
maintained because the pump lacks the necessary capacity. If the pump lacks the necessary capacity, this
programming will therefore reduce the requested flow to a value that will enable the pressure monitoring system to
control the pressure again.
The customer may have noticed a loss of vehicle performance when this program is activated (confirmed by
ET563 Flow capacity function). This is part of normal operation.
Function: Air flow management.
EGR valve control
The EGR (Exhaust gas recirculation) system comprises a proportional EGR valve with a built-in valve position
feedback potentiometer. The EGR valve position is controlled by the potentiometer in a closed loop and/or by
changes in the estimated air flow.
Calculation of the air flow
WITHOUT FLOWMETER (K9K 722)
Certain models are not fitted with air flowmeters. In this case the amount of fresh inlet air must be evaluated, based
on the values supplied by the surrounding systems. The (theoretical) air volume is calculated using a model with
these calculation parameters:
– the inlet air temperature measured by a sensor located after the turbocharger and/or after the intercooler (if fitted),
– the turbocharging pressure,
– the atmospheric pressure (external air),
– the EGR valve position,
– the fuel flow,
– the engine speed.
The atmospheric pressure sensor is optional. If fitted, it sends back an atmospheric pressure signal to an analogue
port on the micro-controller. If not, atmospheric pressure is recovered based on the turbocharger pressure
and the engine field.

13B-12V4 MR-372-J84-13B000$020.mif
DIESEL INJECTION
Fault finding – System operation13B
DDCR INJECTION
Vdiag No.: 44, 48
Functions included
Air conditioning management assistance
For vehicles with air conditioning, the DDCR system can switch off the air conditioning under certain engine
operating conditions:
– when requested by the driver,
– when starting the engine,
– if the engine overheats (in order to reduce the power the engine has to supply),
– when the engine speed is kept at a very high level (to protect the compressor),
– during transition phases (e.g. under heavy acceleration when overtaking, anti-stalling and moving off strategies).
These conditions are only taken into account when they do not occur repeatedly, in order to prevent system
instabilities (erratic deactivations),
– when certain faults appear.
Cold loop air conditioning management
The air conditioning is the cold loop type and its management shared between several computers. The injection
computer is responsible for:
– managing demand for cold air according to the passenger compartment commands and the pressure value,
– determining the power absorbed by the compressor from the pressure,
– determining the fan unit commands according to vehicle speed and pressure.
The driver requests the air conditioning to be switched on by means of the ventilation selector coupled to a switch.
The cold air request is authorised or denied depending on the pressure measured. If this pressure is outside
the operating limits, the cold loop program is not activated.
Thermal regulation of the passenger compartment heating circuit
In a direct injection engine, fuel is injected directly into the combustion chamber. This leads to heat being lost
through the upper part of the engine and consequently, the cylinder head cooling circuit is smaller in size.
The effect of this is that the temperature of the coolant flowing through this circuit rises more slowly. However, this
coolant is also used by the passenger compartment heating system. In very cold conditions, it is therefore difficult to
achieve a comfortable passenger compartment temperature quickly.
To limit the time taken to warm up the system, air heating resistors, called RCHs, are fitted into the passenger
compartment heating circuit. The UCH decides whether the RCH are required, the UPC physically actuates
the RCH, and the injection computer determines whether to limit the power supplied to the RCH depending on
alternator charge, and also whether to disable them according to engine speed, load and vehicle speed. NOTE:
Fan unit actuation requests can be made by the injection computer, but these are sent on the CAN. These requests
depend on the air conditioning but also on the coolant temperature and vehicle speed.

13B-16V4 MR-372-J84-13B000$020.mif
DIESEL INJECTION
Fault finding – System operation13B
DDCR INJECTION
Vdiag No.: 44, 48
48-TRACK BROWN CONNECTOR B
Description Tracks Tracks Description
Flowmeter supply (728, 729) A1 G1 Knock sensor earth (pinking)
Flowmeter signal (728, 729) A2 G2 Fuel temperature signal
Flowmeter earth (728, 729) A3 G3 Fuel temperature sensor earth
Cylinder 1 injector + control A4 G4 Cylinder 4 injector + control
EGR feedback potentiometer supply B1 H1 Not used
EGR feedback potentiometer signal B2 H2 Coolant temperature signal
EGR feedback potentiometer earth B3 H3 Coolant temperature sensor earth
Cylinder 1 injector - control B4 H4 Cylinder 4 injector - control
Turbocharging pressure sensor supply C1 J1 Not used
Turbocharging pressure sensor signal C2 J2 Inlet air temperature signal
Turbocharging pressure sensor earth C3 J3 Inlet air temperature earth (722)
Cylinder 2 injector + control C4 J4 Not used
Rail pressure sensor supply D1 K1 Accelerometer shielding (pinking)
Rail pressure sensor signal D2 K2 External air temperature signal
Rail pressure sensor earth D3 K3 External air temperature earth
Cylinder 2 injector - control D4 K4 Not used
Not used E1 L1 Not used
Phase sensor signal (cylinder) E2 L2 Not used
Phase sensor earth (cylinder) E3 L3 EGR valve control
Cylinder 3 injector + control E4 L4 Not used
Knock sensor signal (pinking) F1 M1 Not used
Engine speed (TDC) sensor + signal F2 M2Turbocharging solenoid valve control
(728, 729)
Engine speed sensor earth (TDC) F3 M3 Not used
Cylinder 3 injector - control F4 M4 Fuel flow actuator control

13B-17V4 MR-372-J84-13B000$020.mif
DIESEL INJECTION
Fault finding – System operation13B
DDCR INJECTION
Vdiag No.: 44, 48
32-TRACK GREY CONNECTOR C
Description Tracks Tracks Description
Not used A1 E1 Not used
Water in diesel fuel detector earth A2 E2 Not used
Not used A3 E3 Not used
Not used A4 E4 Not used
Not used B1 F1 Supply relay control
Not used B2 F2 Preheating relay control
Water in diesel fuel detector signal B3 F3 Not used
Not used B4 F4 Not used
Not used C1 G1 Not used
Not used C2 G2 After relay + battery 1 earth
Refrigerant pressure sensor signal C3 G3 Refrigerant pressure sensor earth
Refrigerant pressure sensor supply C4 G4 Not used
Not used D1 H1 Potentiometer earth Gang 1
Not used D2 H2 Not used
Heater plug diag signal D3 H3 After relay + battery 2
Not used D4 H4 Not used
NOTE:
The supply voltage on tracks G2 and H2 is not measurable when the computer connector is disconnected.

13B-23V4 MR-372-J84-13B000$050.mif
DIESEL INJECTION
Fault finding – Fault summary table13B
DDCR INJECTION
Vdiag No.: 44, 48
Tool faultAssociated
DTCDiagnostic tool title
DF049 0530 Refrigerant sensor circuit
DF050 0571 Brake switch circuit
DF051 0575 Cruise control/speed limiterfunction
DF052 0200 Injector control circuit
DF053 0089 Rail pressure regulation function
DF054 0033 Turbocharging solenoid valve control circuit (728, 729)
DF056 0100 Air flow sensor circuit (728, 729)
DF057 2264 Water in diesel fuel detector circuit
DF059 0301 Misfiring on cylinder 1
DF060 0302 Misfiring on cylinder 2
DF061 0303 Misfiring on cylinder 3
DF062 0304 Misfiring on cylinder 4
DF089 0235 Inlet manifold pressure sensor circuit
DF098 0180 Fuel temperature sensor circuit
DF107 0604 Computer memory
DF112 0340 Cylinder reference sensor circuit
DF113 0608 Sensor feed voltage
DF114 0400 EGR solenoid valve circuit
DF116 C001 Multiplex network
DF121 0325 Accelerometer circuit
DF122 0609 Supply voltage pedal potentiometer gang 2
DF130 0087 Flow capacity function
DF1070 0534 Cold loop