DIESEL INJECTION
Fault finding – System operation13B
13B - 9V3 MR-372-J84-13B250$135.mif
EDC16
PROGRAM No: C1
Vdiag No.: 51DIESEL 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 is comprised of:
–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 flow sensor with an air temperature sensor,
–a turbocharging pressure limitation solenoid valve,
–a motorised damper valve.
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-J84-13B250$135.mif
DIESEL INJECTION
Fault finding – System operation13B
13B - 10V3 MR-372-J84-13B250$135.mif
EDC16
PROGRAM No: C1
Vdiag No.: 51
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.
Determines the injection duration necessary for supplying the correct quantity of diesel and the moment when
injection is required; controls each injector electrically and individually after determining these 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 CMV control via the Protection and Switching Unit (centralised coolant temperature management function),
–the air conditioning (cold loop function),
–the cruise control/speed limiter function,
–pre-post heating control,
–fault warning lights via the multiplex network.
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 fuel flow actuator enables the high
pressure pump to supply the exact quantity of diesel fuel required to maintain the rail pressure. 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.
DIESEL INJECTION
Fault finding – System operation13B
13B - 12V3 MR-372-J84-13B250$135.mif
EDC16
PROGRAM No: C1
Vdiag No.: 51
c) Hosted functions:
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 transitory phases (such as demands for high acceleration when overtaking, anti-stall and start-up) These
conditions are only taken into account when they do not occur repeatedly, to prevent instability in the system
(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:
–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 currently 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.
–"valving" function depending on the engine operation: the damper valve closes by a few % to create a ''venturi''
effect at the EGR valve passage section.
The aim of this is to accelerate the air flow of EGR gases and to reduce the emission of pollutants.
DIESEL INJECTION
Fault finding – Replacement of components13B
13B-23V3 MR-372-J84-13B250$225.mif
EDC16
PROGRAM No: C1
Vdiag No.: 51
REPLACING OR CLEANING THE EXHAUST GAS RECIRCULATION VALVE (EGR valve)
After the exhaust gas recirculation valve has been replaced or cleaned, the computer must store the new valve's
offset and the offset measured the last time the ignition was switched off, which is when the valve closed.
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 program is compiled in the Emission control/OBD sub-function.
–PR128: First EGR valve offset.
–PR129: Last EGR valve offset or = PR128 for a new valve.
Programming PR128 and PR129 must be cleared every time the exhaust gas recirculation valve is replaced.
→ PROCEDURE:
–run command SC036 Reset programming;
–select EGR valve as the operation type 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 next 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.
The last EGR valve offset reprogrammed is stored on the computer.
–then check the system faults, and clear any stored faults;
–otherwise deal with faults which are present and clear the faults in the computer memory.
Carry out a road test followed by a complete check with the diagnostic tool.
End of operation.Note:
When the reinitialisation is completed, 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 new EGR valve offset has been reprogrammed, theEmission control/OBDsub-function displays:
10% < PR128 < 40%
10% < PR129 < 40%
DIESEL INJECTION
Fault finding – Glossary13B
13B -273V3 MR-372-J84-13B250$945.mif
EDC16
PROGRAM No.: C1
Vdiag No.: 51DIESEL INJECTION
Fault finding – Glossary
(R = Resistance, EGR = Exhaust gas recirculation, FAP = Particle filter)Injection computer112-track (BOSCH)
Connectors: black A 32-track, brown B 48-track, grey C 32-track
Atmospheric pressure sensor Integrated into the computer (BOSCH)
Injector0.23 Ω at + 20˚C/2 Ω max (BOSCH)
1600 bar
Flow regulator (high pressure
pump)R = 3 Ω at + 20˚C (BOSCH, CP3.2+ pump type)
Rail pressure sensorPressure limiter on the rail: opening around 1800 bar
(BOSCH, bolted to the rail)
Engine speed sensor R = 680 ± 170 Ω at +20˚C (MGI)
Camshaft sensorHall effect sensor (ELECTRICFIL)
R = 10250 ± 500 Ω at + 20˚C (measurement between tracks 2 and 3 of the
sensor)
Turbocharger control solenoid valve 15.4 ± 0.7 Ω at + 20˚C (PIERBURG)
Electric EGR valveTrack 1: + 12 V electric motor
Track 2: + 5 V potentiometer
Track 3: Not usedTrack 4: potentiometer earth
Track 5: engine earth
Track 6: potentiometer signal
DIRECT CURRENT MOTOR: R between tracks 1 and 5 = between 1 Ω and
400 Ω at + 20˚C
POTENTIOMETER: R between tracks 2 and 4: 6.5 ± 2.4 kΩ at + 20˚C
(SIEMENS)
Electrical damper valve MOTOR (VDO)
Air flowmeterTrack 1: air temperature signal
Track 2: flow sensor earth
Track 3: + 5 V flowmeterTrack 4: + 12 V battery
Track 5: air flow signal
Track 6: battery earth
(SIEMENS)
Air temperature sensor R = 3714 Ω ± 161 at + 10˚C/2448 Ω ± 96 at + 20˚C/1671 Ω ± 59 at + 30˚C
Coolant temperature sensor R = 2252 Ω ± 112 at 25˚C/811 Ω ± 39 at 50˚C/283 Ω ± 8 at 80˚C
Accelerator pedal sensorR gang 1 = 1700 ± 900 Ω;
R gang 2 = 2850 ± 2050 Ω
Heater plugR = 0.6 Ω at + 20˚C/2 Ω max
Maximum current drawn: 28 A at 0 seconds/12 A at 10 seconds/9 A after
30 seconds
Water in diesel fuel sensor According to application (ZERTAN)