13B-7V4 MR-372-J84-13B000$010.mif
DIESEL INJECTION
Fault finding – Introduction13B
DDCR INJECTION
Vdiag No.: 44, 48
Advice to be followed before any operation
Protect the accessories and timing belts, the electrical accessories (starter, alternator, electric power assisted
steering pump) and the mating face to prevent diesel fuel spilling onto the clutch friction plate).
Check that you have plugs for the unions to be opened (set of plugs available from the Parts Department). The plugs
are single-use only. After use, they must be discarded (once used they are soiled and cleaning is not sufficient to
make them reusable). Unused plugs must be discarded.
Ensure that you have hermetically resealable plastic bags for storing removed parts. Parts stored in this way will be
less susceptible to the risk of contamination. These are single-use bags; after use they must be discarded.
Use lint-free cleaning cloths (part no. 77 11 211 707). Using normal cloth or paper is prohibited. They are not lint-free
and could contaminate the fuel circuit. Each cloth should only be used once.
Use fresh cleaning agent for each operation (used cleaning agent is contaminated). Pour it into an uncontaminated
container.
For each operation, use a clean brush in good condition (the brush must not shed its bristles).
Use a brush and cleaning agent to clean the unions to be opened.
Blow compressed air over the cleaned parts (the tools and workbench, as well as the parts, unions, and injection
system sections). Check that no bristles remain.
Wash your hands before and during the operation if necessary.
When wearing leather protective gloves cover them with latex gloves to prevent contamination.
Instructions to be followed during the operation
As soon as the circuit is open, all openings must be plugged to prevent impurities from entering the system.
The plugs to be used are available from the Parts Department. They must not be reused under any circumstances.
Close the hermetically sealed bag, even if it has to be reopened shortly afterwards. Ambient air carries impurities.
All components removed from the injection system must be stored in a hermetically sealed plastic bag once they
have been plugged.
Using a brush, cleaning agent, air gun, sponge or normal cloth is strictly prohibited once the circuit has been
opened. These items are likely to allow impurities to enter the system.
A new component replacing an old one must not be removed from its packaging until it is to be fitted to the vehicle.
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-58
AFTER REPAIRDeal with any faults declared by the diagnostic tool. Clear the computer fault memory.
Carry out a road test followed by another check with the diagnostic tool.
V4 MR-372-J84-13B000$062.mif
13B
DDCR INJECTION
Vdiag No.: 44, 48
DF053
STOREDRAIL PRESSURE REGULATION FUNCTION
1.DEF: At minimum limit
2.DEF: At maximum limit
3.DEF: Below minimum threshold
4.DEF: Above maximum threshold
5.DEF: High flow current < minimum
6.DEF: High flow current > maximum
7.DEF: Low flow current < minimum
8.DEF: Low flow current > minimum
NOTESSpecial notes:
If DF053, the engine may stop, with the level 1 and 2 warning lights illuminated along
with the message Faulty injection.
Priority when dealing with a number of faults:
– DF007 Rail pressure sensor circuit,
– DF098. Fuel temperature sensor circuit.
Conditions for applying fault finding procedures to stored faults:
The fault is present with the engine running.
4.DEF
6.DEF
8.DEF
NOTESNone.
Check the connection and condition of the fuel flow actuator connector (brown IMV connector on the pump).
Repair if necessary.
Measure the resistance between tracks 1 and 2 of the flow actuator.
Replace the flow actuator if the resistance is not 5.3 Ω +
0.5 Ω at 20°C.
Check the connection and condition of the computer 48-track brown connector B.
Repair if necessary.
Check the insulation, continuity, and the absence of interference resistance on the following connection:
Computer connector B track M4 Track 1 fuel flow actuator
Repair if necessary.
Check that there is fuel present in the tank and that it is correct. Run Test 13 Diesel fuel conformity check.
Run Test 1 Low pressure circuit check.
DDCR_V44_DF053M/DDCR_V48_DF053M
DIESEL INJECTION
Fault finding – Interpretation of faults
13B-94V4 MR-372-J84-13B000$070.mif
DIESEL INJECTION
Fault finding – Conformity check13B
DDCR INJECTION
Vdiag No.: 44, 48
FUEL CIRCUIT SUB-FUNCTION (continued 1):
NOTESOnly check conformity after a full check with the diagnostic tool.
The values shown in this conformity check are given as examples.
Application conditions: Engine off, ignition on.
FunctionParameter or Status
Check or actionDisplay and notes Fault finding
Rail pressure
sensor
voltagePR080: Rail pressure
sensor voltage.
Cold: 0.5 V
Warm: 4.5 VShows the voltage supplied by the
computer to the rail pressure
sensor.
0.5 V < PR080 < 4.5 V
Default value: 4.5 VNONE
Engine speed PR055: Engine speedIndicates the engine's speed of
rotation in rpm.In the event of a fault,
apply the fault finding
procedure for
DF005 "Engine speed
sensor circuit".
New pump
chamber
fillingET637: New pump
chamber fillingCOMPLETEDIf NOT DONE, see
Replacement of
components.
13B-99V4 MR-372-J84-13B000$070.mif
DIESEL INJECTION
Fault finding – Conformity check13B
DDCR INJECTION
Vdiag No.: 44, 48
EMISSION CONTROL/OBD SUB-FUNCTION:
NOTESOnly check conformity after a full check with the diagnostic tool.
The values shown in this conformity check are given as examples.
Application conditions: Engine off, ignition on.
FunctionParameter or Status
Check or actionDisplay and notes Fault finding
EGR valve
controlET008: EGR valve
control.
INACTIVEIndicates the EGR valve control
status.
- INACTIVE: The valve is not
controlled by the computer.
- ACTIVE: The valve is controlled
by the computer.NONE
Atmospheric
pressurePR035: Atmospheric
pressure.Indicates the atmospheric
pressure in mbar. The sensor is
built into the computer.If not consistent, check that
PR035 = PR032 = local
atmospheric pressure, with
the engine stopped
and the ignition on.
Air flow PR132: Air flow.Air flow estimated by the
injection computer.NONE
Fuel flowPR017: Fuel flow.
0.0 mg/stGives the fuel flow at the high
pressure pump outlet in mg/st.NONE
EGR valve
opening
setpointPR005: EGR valve
opening setpoint.
Warm or cold = -50Gives a theoretical EGR valve
opening value for optimum
engine operation.
PR005 = PR051NONE
EGR valve
position
feedbackPR051: EGR valve
position feedback.
Warm or cold = -50Shows the true EGR valve
position.
PR051 = PR005NONE
13B-114V4 MR-372-J84-13B000$070.mif
DIESEL INJECTION
Fault finding – Conformity check13B
DDCR INJECTION
Vdiag No.: 44, 48
FUEL CIRCUIT SUB-FUNCTION (continued):
NOTESOnly check conformity after a full check with the diagnostic tool.
The values shown in this conformity check are given as examples.
Application conditions: Engine off, ignition on.
FunctionParameter or Status
Check or actionDisplay and notes Fault finding
Engine speedPR055: Engine speed.
Cold: 900 rpm.
Warm: 805 rpm.Indicates the engine's speed of
rotation in rpm.In the event of a fault,
apply the fault finding
procedure for
DF005 "Engine speed
sensor circuit".
New pump
chamber fillingET637: New pump
chamber fillingCOMPLETEDIf NOT DONE, see
Replacement of
components.