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 – Fault Finding Chart13B
13B -235V3 MR-372-J84-13B250$855.mif
ALP8 Oil leaks from the turbocharger
NOTESBefore dealing with this customer complaint, check that there are no faults, and
the conformity (or otherwise) of the parameters and statuses using the
diagnostic tool.
If the customer complaint is not ironed out, perform the following checks:
Check the area around the turbocharger
Note:
An oil leak does not correspond always to a turbocharger fault, the oil leak can arise from the area around the
turbocharger.
According to the vehicle type, maximum visual access will either be from above or from below.
1Do not start the engine.
Check the area around the turbocharger and identify the origin of the leaks.
Clean the oil traces on the turbocharger.
2start the engine and let it warm up for several minutes.
IMPORTANT
If the air filter was removed previously, refit it before starting the engine (risks foreign matter entering the air inlet
circuit).
Accelerate with no load several times, progressively increasing the duration before releasing the accelerator pedal.
Visually inspect the exterior condition of the fuel supply pipes and the turbocharger oil return and the area around it.
Identify the origin of the leaks.
Is an oil leak present at the air compressor inlet or outlet?
YESNO
Check the air compressor inlet or outlet
Check for a loose interface (inlet or outlet) that is the cause of the air leak.
Note:
it is normal to find traces of oil inside the pipes at the turbocharger inlet or outlet as the air
passing into the compressor is laden with oil from the engine rebreathing circuit.
Is the suspected interface properly tightened?
YES NO
Replace the pipe concerned (see MR
364 (Mégane II) or 370 (Scénic II),
Mechanical systems, 12B,
turbocharging).Tighten the interface or the concerned
pipe.
End of procedure.
AFTER REPAIRCarry out a road test followed by a complete check with the diagnostic tool.
EDC16
PROGRAM No.: C1
Vdiag No.: 51
EDC16_V51_ALP8
DIESEL INJECTION
Fault finding – Test13B
13B -264V3 MR-372-J84-13B250$900.mif
TEST9 Air path around the turbocharger
Check for the air filter
Check the replacement frequency for the air filter in the Maintenance Booklet.
Compare the part numbers of the air filter fitted to the vehicle and that of the air filter recommended by the
manufacturer.
Check the air filter direction of fitting.
Is the air filter fitted to the vehicle correct?
YES NO
Check the condition of the air filter
Visually inspect the condition of the filter
section of the air filter.
Is either the air filter or its seal
damaged?
Is the air filter clogged (does it contain
a lot of impurities)?YESReplace the air filter (see MR 364
(Mégane II) or 370 (Scénic II),
Mechanical, 12A, Fuel mixture, Air
filter, Removal - Refitting).
NO
Low pressure circuit check
Note:
According to the vehicle type, maximum
visual access will either be from above or
from below.
Visually inspect the condition of the
following components:
–fresh air inlet scoop on the front end
panel of the vehicle,
–air filter air inlet pipe,
–filter air pipe up to the compressor
inlet,
–air flowmeter mountings.
Is one of these components incorrect
(disconnected, cut, bent, pierced or
kinked pipes)?YESReplace the defective parts (see MR 364
(Mégane II) or 370 (Scénic II),
Mechanical, 12B, Turbocharging).
EDC16
PROGRAM No.: C1
Vdiag No.: 51
EDC16_V51_TEST9
DIESEL INJECTION
Fault finding – Test13B
13B -266V3 MR-372-J84-13B250$900.mif
EDC16
PROGRAM No.: C1
Vdiag No.: 51
TEST10 Diesel fuel conformity check
WARNING
During t hisop eration, it is essential t o:
–refrain from smoking or bringing incandescent objects close to the work area,
–protect yourself against fuel splashes due to residual pressure in the pipes,
–wear safety goggles with side guards,
–wear leaktight gloves (Nitrile type).
IMPORTA NT
–To avoid any corrosion or damage, protect the areas on which fuel is likely to run.
–To prevent impurities from entering the circuit, place protective plugs on all fuel circuit components
exposed to the open air.
Preparations:
Weigh an empty 1300 ml plastic cup (part no. 77 11 171 413) with its cover (part no. 77 11 171 416) using
electronic scales such as those used in body paint workshops (example: PANDA part no. 77 11 224 995). Record
the weight of the empty plastic cup.
This type of plastic cup is used to prepare paint.
Remove 1 litre of fuel at the diesel filter outlet (see MR 364 (Mégane II) or MR 370 (Scénic II), Mechanical,
19C, Tank, Draining the fuel tank), using a pneumatic transfer pump (part no. 634-200) and place it in the
1300 ml plastic cup.
Cover the plastic cup with its cover and let it settle for approximately 2 minutes.
Is the fuel cloudy or does it
separate into two parts?YESThe diesel fuel contains water and is not compliant.
Drain the fuel circuit, including the tank (see MR 364
(Mégane II) or MR 370 (Scénic II), Mechanical, 19C,
Tank, Draining the fuel tank).
NO
EDC16_V51_TEST10
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)