13B-11
MR-372-J84-13B200$108.mif
V13
13B
DIESEL INJECTION
Fault finding – System operation
System outline
The high pressure injection system is designed to deliver a precise quantity of diesel fuel to the engine at a set
moment.
It is fitted with a 112-track BOSCH EDC16 C3 type computer.
The system comprises:
– a priming bulb on the low pressure circuit,
– a diesel filter,
– a high pressure pump with a built-in low pressure pump (transfer pump),
– a high pressure regulator mounted on the pump,
– an injector rail,
– a diesel fuel pressure sensor built into the rail,
– four solenoid injectors,
– a coolant temperature sensor,
– a cylinder reference sensor,
– an engine speed sensor,
– a turbocharger pressure sensor,
– an accelerator pedal potentiometer,
– an EGR solenoid valve,
– an atmospheric pressure sensor integrated into the injection computer,
– an air flowmeter with an air temperature sensor,
– a turbocharging pressure limitation solenoid valve,
– a motorised damper valve,
– a particle filter,
– a particle filter differential pressure sensor,
– a particle filter upstream temperature sensor,
– a particle filter downstream temperature sensor,
– a temperature sensor upstream of the turbine,
– four thermoplungers
The common rail direct high pressure injection system works sequentially (based on the petrol engine multipoint
injection).
This injection system reduces operating noise, reduces the volume of pollutant gases and particles and produces
high engine torque at low engine speeds thanks to a pre-injection procedure.
The high pressure pump generates the high pressure and transmits it to the injector rail. The actuator located on the
pump controls the quantity of diesel fuel supplied, according to the requirement determined by the computer. The rail
supplies each injector through a steel pipe.
MR-372-J84-13B200$108.mif
EDC16
Program No: C1
Vdiag No: 18, 1C, 20,
50, 58, 5C
13B-12
MR-372-J84-13B200$108.mif
V13
DIESEL INJECTION
Fault finding – System operation
EDC16
Program No: C1
Vdiag No: 18, 1C, 20,
50, 58, 5C
13B
a) The computer:
Determines the value of injection pressure necessary for the engine to operate correctly and then controls the
pressure regulator.
Checks that the pressure value is correct by analysing the value transmitted by the pressure sensor located on the
rail.
It determines the injection timing required to deliver the right quantity of diesel fuel and the moment when injection
should start. Controls each injector electrically and individually after determining these two values.
The flow injected into the engine is determined by:
– the duration of injector control,
– the rail pressure (regulated by the computer),
– the injector opening and closing speed,
– the needle stroke (determined by a constant for the type of injector),
– the nominal hydraulic flow of the injector (specific to each injector).
The computer manages:
– idling regulation,
– exhaust gas flow reinjection to the inlet (EGR),
– fuel supply check (advance, flow and rail pressure),
– the fan assembly control,
– the air conditioning (cold loop function),
– the cruise control/speed limiter function,
– pre-post heating control,
– indicator lights control via the multiplex network,
– the operation of the catalysed particle filter.
The high pressure pump is supplied at low pressure by an integrated low pressure pump (transfer pump).
It supplies the rail, the pressure of which is controlled by the fuel flow actuator (MPROP) for charging, and for
discharging by the injector valves. This compensates for pressure drops. The flow actuator allows the high pressure
pump to supply the exact quantity of diesel fuel required to maintain the pressure in the rail. This component
minimises the heat generated and improves engine output.
In order to discharge the rail using the injector valves, the valves are controlled by brief electrical pulses which are:
– short enough not to open the injector (passing through the feedback circuit from the injectors),
– long enough to open the valves and discharge the rail.
13B-14
MR-372-J84-13B200$108.mif
V13
DIESEL INJECTION
Fault finding – System operation
EDC16
Program No: C1
Vdiag No: 18, 1C, 20,
50, 58, 5C
13B
c) Functions hosted:
Air conditioning management assistance:
In the case of vehicles with climate control, the EDC16 system has the option of deactivating the air conditioning via
the UCH, under certain conditions of use:
– 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. high acceleration demand for overtaking, anti-stalling and moving off). These
conditions are only taken into account if they do not occur repeatedly, so as to prevent system instabilities
(erratic deactivation),
– when certain faults appear.
Cold loop air conditioning management (Mégane II only):
The air conditioning is the cold loop type and its management shared between several computers.
The injection computer is responsible for:
– authorising cold requests according to the refrigerant pressure, the engine coolant temperature and the engine
speed,
– calculating the power absorbed by the compressor (from the refrigerant pressure),
– requesting operation of the GMV, from the UPC, according to the vehicle speed, the refrigerant pressure and the
engine coolant temperature.
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.
Management of the damper valve:
The damper valve has three functions:
– the valve closes in order to block the passage of air towards the cylinders to shut off the engine. The aim of this is
to stop the engine as quickly as possible and to reduce instabilities as the engine is switched off.
– a "valving" function depending on the various engine functions: the damper valve closes by a few % in order to
create a venturi effect in the EGR valve flow section.
The aim of this is to accelerate the EGR gas flow rate and to reduce the emission of pollutants.
– regulatory function during the regeneration of the particle filter.
Thermoplunger management (only for Vdiag 58, 5C,18, 1C and 20):
This vehicle is fitted with thermoplungers. They are managed and activated by the injection system.
See configuration reading LC056 Thermoplungers: WITH or WITHOUT.
When necessary, the thermoplungers are actuated by the injection system only during particle filter
regeneration by means of a specific unit.
The maximum number of thermoplungers that can be managed is four; their activation depends mainly on the
coolant temperature (< 15°C) and air temperature (< 5°C).
13B-24
MR-372-J84-13B200$144.mif
V13
DIESEL INJECTION
Fault finding – Replacement of components
EDC16
Program No: C1
Vdiag No: 18, 1C, 20,
50, 58, 5C
13B
REPLACING OR CLEANING THE EXHAUST GAS RECIRCULATION (EGR) VALVE
After the exhaust gas recirculation valve has been replaced, the computer must store the new valve offset and the
offset measured when the ignition was last switched off, which corresponds to the valve closing.
Using this data, the computer can detect whether the valve is clogged or seized.
When the valve is replaced or cleaned, clear the stored offsets so that the program uses the new valve's offset
value.
The data linked to this strategy is compiled in the Antipollution/OBD sub-function.
– PR128 First EGR valve offset.
– PR129 Last EGR valve offset > or = PR128 for a new valve.
The PR128 and PR129 programming must be cleared every time the exhaust gas recirculation valve is replaced.
PROCEDURE:
– Run command SC036 Reinitialise programming.
–Select EGR valve as the type of operation, then follow the instructions given by the diagnostic tool.
When the command is finished,
– switch off the ignition,
–wait 1 minute before switching on the ignition again.
When the ignition is switched on again, the new EGR valve offset is automatically reprogrammed.
– start the vehicle to enable the latest EGR valve offset to be programmed,
– switch off the ignition,
–wait 1 minute before switching on the ignition again.
Reprogramming of the last EGR valve offset is stored in the computer.
– then check the system faults, and clear any stored faults,
– otherwise, deal with the faults that are present and clear the faults in the computer memory.
Carry out a road test followed by another check with the diagnostic tool.
End of operation.Note:
When the reinitialisation is complete, the Emission control/OBD sub-function displays:
PR128 = PR129 > 100 %
Note:
When the new EGR valve offset has been reprogrammed, the Emission control/OBD sub-function displays:
10 % < PR128 < 40 %
PR129 > 100 %
Note:
When the last EGR valve offset has been reprogrammed, the Emission control/OBD sub-function displays:
10 % < PR128 < 40 %
10% < PR129 < 40%