tire pressure RENAULT SCENIC 2011 J95 / 3.G Engine And Peripherals Workshop Manual

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DIESEL INJECTION
Fault finding – Introduction13B
DDCR INJECTION
Vdiag No.: 44, 48
4. FAULT FINDING PROCEDURE (continued)
Wiring check
Fault finding problems
Disconnecting the connectors and/or manipulating the wiring may temporarily clear the cause of a fault.
The electrical measurements of the voltage, resistance, and insulation are generally correct, especially if the fault is
not present when the measurements are being taken (stored fault).
Visual inspection
Look for damage under the bonnet and in the passenger compartment.
Carefully check the fuses, insulators and wiring harness routing.
Look for signs of oxidation.
Physical inspection
When handling the wiring, use the diagnostic tool to detect any change in the status of the fault from stored to
present.
Make sure that the connectors are firmly locked.
Apply light pressure to the connectors.
Twist the wiring harness.
If there is a change in status, try to locate the source of the fault.
Inspection of each component
Disconnect the connectors and check the appearance of the clips and tabs as well as their crimping (no crimping on
the insulation). Check that the clips and the tabs are correctly locked in the sockets.
Check that no clips or tabs have been dislodged during connection.
Check the clip contact pressure using an appropriate model of tab.
Resistance check
Check the continuity of entire lines, then section by section.
Look for a short circuit to earth, to + 12 V or with another wire.
If a fault is detected, repair or replace the wiring harness.
5. FAULT FINDING LOG
IMPORTANTIMPORTANT
Any fault on a complex system requires thorough fault finding with the appropriate tools.
The FAULT FINDING LOG, which should be completed during the procedure, enables you to
keep track of the procedure which is carried out. It is an essential document when consulting
the manufacturer.
IT IS THEREFORE COMPULSORY TO COMPLETE A FAULT FINDING LOG EVERY TIME A FAULT FINDING
PROCEDURE IS PERFORMED

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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

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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.

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DIESEL INJECTION
Fault finding – Interpretation of parameters13B
DDCR INJECTION
Vdiag No.: 44, 48
CLEARING
RZ001: fault memory.
This command is used to clear stored faults from the computer's memory.
RZ002: EGR adaptives.
Run this command only when replacing the EGR valve.
RZ004: Pressure regulation parameters.
Run this command when replacing all 4 injectors at once. It enables you to reset the injector adaptive programs.
RZ005: Programming.
This command lets you reinitialise the entire computer configuration according to the vehicle.
COMMANDS
LPG - FUEL CIRCUIT tab
AC010: High-pressure pump.
This command lets you listen for the operation of the high pressure pump.
AC005 to AC008: Injectors of cylinders 1 to 4.
These commands let you listen for the injector on the selected cylinder.
AC028: Static test.
This command activates fault finding for the EGR and high pressure pump circuits.
AC029: High-pressure circuit seal check.
This command lets you check the high pressure circuit sealing after a procedure has been carried out.
AC212: New pump chamber filling.
Use this command only after replacing the high pressure pump (see High pressure pump replacement in
Replacement of components). This command is used to activate the pump repriming sequence.
IGNITION - PREHEATING tab
AC001: Preheating unit.
This command actuates the preheating unit to test the heater plug supply.
EMISSION CONTROL - OBD tab
AC002: EGR solenoid valve.
This command lets you listen to the mechanical operation of the EGR valve.
AC028: Static test.
This command activates fault finding for the EGR and high pressure pump circuits.
TURBO - INLET AIR CIRCUIT tab
AC004: Turbocharging solenoid valve.
This command lets you listen for the operation of the turbocharging solenoid valve.