2000 FIAT MAREA AUTO

Marea- Marea Weekend © ™ Engine
2000 range Q Fuel feed system
10.
FUEL SYSTEM
INTRODUCTION
Marea and Marea Weekend 1.9 JTD cars are equipped with a 4 cylinder in line, 1910 cc turbodiesel en­
gine with two valves per cylinder, an overhead camshaft, turbocharger and intercooler and electronic in­
jection.
The fuel system ensures correct engine operation and can be divided into the following subsystems:
- Fuel feed circuit with common rail injection;
- air feed circuit;
- exhaust circuit;
- blow by vapour recirculation circuit;
- Exhaust Gas Recirculation (EGR) circuit
Operation of the various circuits making up the fuel system is optimised by an electronic control system
managed by a special control unit.
The main feature of the fuel system is common rail fuel injection. Common rail is a higher pressure elec­
tronic injection system for fast direct injection diesel engines.
The main features of the common rail system are as follows:
- availability of high injection pressures (up to 1350 bars);
- possibility of modulating these pressures (from a minimum of 150 bars to a maximum of 1350 bars)
independently of engine speed (rpm) and engine load;
- ability to operate at high engine speeds (up to 6000 rpm);
- precise injection control (injection advance and duration);
- reduced fuel consumption;
- reduced emissions.
FUEL SYSTEM MANAGEMENT STRATEGIES
The management program (software) is stored inside the control unit memory and consists of a series of
strategies, each of which manages a precise system control function.
Through the use of information providd by the various sensors (input), each strategy processes a set of
parameters based on data stored in special control unit memory areas. It then controls system actuators
(output), i.e. the devices that allow the engine to operate.
The main purpose of these management strategies is to determine the exact amount of fuel to be injected
into the cylinders with timing (injection advance) and pressure designed to achieve the best possible en­
gine performance in terms of power, fuel consumption, fumes, emissions and handling.
The main system management strategies are essentially as follows:
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of injected fuel quantity;
of injection advance;
of injection pressure;
of auxiliary fuel pump;
of injection during over-run (cut-off);
of idle speed;
of maximum speed limitation;
of maximum torque limitation;
of fuel temperature;
of engine coolant temperature;
of air turbocharging pressure;
of glow plugs;
of exhaust fumes;
of exhaust gas recirculation (EGR);
of climate control system activation;
control of engine immobiliser operation (Fiat
CODE);
self-diagnosis
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Ma tea- Marea Weekend 9 ™
2000 range (Q) Fuel feed system
Engine
10.
Control of injected fuel quantity
The control unit controls the fuel pressure regulator and injectors on the basis of output signals from the
accelerator pedal potentiometer, flow meter and rpm sensor.
The timing and thus the injection sequence are determined when the engine is started up using signals
from the rpm and timing sensor (synchronisation stage); injection timing is then implemented using the
rpm sensor signal alone and considering a injection sequence of 1 -3-4-2.
The control unit inhibits injection in the following cases:
- fuel pressure level greater than 1500 bars;
- fuel pressure level lower than 120 bars;
- engine speed higher than 6000 rpm.
When the engine has warmed up, maximum injection duration (injector opening time) is 1500 ns, but it
can reach 3000 ns during the start-up stage.
Control of injection advance
The electronic control unit determines injection advance mainly on the basis of the quantity of fuel to be
injected.
The injection advance is then corrected on the basis of coolant temperature and speed in order to com­
pensate for ignition delays due to low temperatures in the combustion chamber during warm-up.
The optimum injection point is also processed to ensure driving comfort and emission limits laid down by
Euro 3 legislation.
Control of injection pressure
This control is of particular importance because injection pressure influences the following parameters:
- amount of fuel taken into the cylinders for the same injection time duration;
- injected fuel nebulation;
- spray penetration;
- lag between electrical control to injection and actual injection start and end times.
The above parameters engine behaviour significantly, particularly in terms of power output, exhaust emis­
sions, noise levels and handling.
The injection control unit controls the pressure governor on the basis of engine load to obtain an optimal
line pressure at all times.
When the engine is cold, injection pressure is corrected on the basis of engine speed and engine coolant
temperature to meet engine needs at different operating temperatures.
Control of auxiliary fuel pump
The auxiliary fuel pump submerged in the tank is supplied by the injection control unit by means of a relay
when the ignition key is turned on.
Fuel supply to the pump is inhibited when one of the following condition occurs:
- when the ignition has been turned on for a certain length of time without the engine running;
- if the inertia switch cuts in.
Control of injection during over-run (cut-off)
The fuel cut-off strategy is implemented when the injection control unit receives information that the ac­
celerator pedal has been released from the potentiometer.
Under these conditions, the control unit cuts off the fuel supply to the injectors and restores it before idle
speed is reached.
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Marea-Marea Weekend 9]
2000 range (j§)
I) JTD
Fuel feed system
Engine
10.
Exhaust fumes control
Through this function the injection control unit limits any exhaust fumes that could be produced during
transition speeds.
To satisy these requirements the control unit processes the signals supplied by the accelerator pedal po­
tentiometer, the rpm sensor and the air flow meter and controls the fuel pressure regulator and the injec­
tors to meter the correct amount of fuel to inject.
Exhaust gas recirculation control
On the basis of the signals supplied by the rpm sensor, intake air quantity sensor, engine coolant tempe­
rature sensor and accelerator pedal position sensor, the control unit calculates the operating times for the
EGR valve so that the exhaust gases are partly recirculated in certain engine operating conditions in line
with Euro 3 pollution control standards.
Air conditioning system engagement control
The injection control unit manages the operation of the air conditioning system compressor electro­
magnet coupling following a logic aimed at preventing operating conditions that would adversely affect
engine performance.
- When the compressor is switched on the injection control unit increases the quantity of fuel during
idling to allow the engine to adjust to the increased power requirements and momentarily interrupts the
supply to the compressor in high engine power requirement conditions (strong acceleration).
Engine immobilizer function control
The system is equipped with an engine immobilizer function. This function is achieved through the pre­
sence of a specific control unit (Fiat CODE), capable of conversing with the injection control unit and an
electronic key with a special transmitter for sending a recognition code.
Each time the key is turned to the OFF position, the Fiat CODE system completely deactivates the injecti­
on control unit.
When the key is turned to the ON position the following operations take place, in order:
1. the injection control unit (whose memory contains a secret code) sends the Fiat CODE control unit a
request to send the secret code to deactivate the immobilizer functions;
2. the Fiat CODE control unit responds by only sending the secret code after, in turn, having received the
recognition code transmitted by the ignition key;
3. the recognition of the secret code allows the deactivation of the injection control unit immobilizer func­
tion and its normal operation.
Autodiagnosis
The complete electronic fault diagnosis of the injection system is carried out by connecting the special
equipment (EXAMINER or EXAMINER PLUS) to the standardized diagnostic socket (EOBD).
The system is also equipped with a self-diagnostic function which recognizes, memorizes and signals any
faults.
If a fault is detected in the sensors or actuators, the recovery strategy is immediately activated in order to
ensure that the engine functions at an acceptable level. The vehicle can be driven to a service centre for
the appropriate repairs to be carried out.
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Fuel feed system
Engine Marea- Marea Weekend © ™
2000 range @
10.
The control unit autodiagnostic system checks the signals coming from the sensors and compares them
with the figures allowed:
- signalling faults during starting
- warning light on for 4 seconds indicates test stage
- warning light off after 4 seconds indicates no fault with components that could alter the pollution con­
trol standard figures
- warning light on after 4 seconds indicates fault.
- signalling faults during operation
- warning light on indicates fault
- warning light off indicates no fault with components that could alter the pollution control standard fig­
ures.
- recovery
- from time to time, the control unit defines the type of recovery according to the components which are
faulty
- the recovery parameters are managed by components which are not faulty.
Control of cylinder balancing during idling
According to the signals coming from the sensors, the injection control unit controls the idle speed torque,
altering the injector operating times.
Control of irregular operation
Depending on the signals coming from the sensors, the injection control unit corrects the amount of fuel
to be injected in order to improve driveability and reduce jerking whilst driving.
The correction is achieved through the fuel pressure regulator and by varying the injector operating times.
Control of electrical balance
According to the battery voltage, the injection control unit alters the idle speed, to guarantee a sufficient
current supply from the alternator in situations where the consumers are absorbing a great deal of power.
The variation in the idle speed is achived by regulating the fuel pressure and altering the injector operat­
ing times.
VGT variable geometry turbocharger control (1910 JTD 110 CV)
The injection control unit processes the signal coming from the supercharging sensor, at the various en­
gine operating speeds, and determines the quantity of fuel to be injected, acting on the fuel pressure
regulator and the injector opening times.
In addition, through the solenoid valve, the control unit regulates the geometry of the turbine in order to
ensure optimum performance in all operating conditions.
Turbocharger waste gate valve control (1910 JTD 100 CV)
At the various engine operating speeds, the injection control unit processes the signal coming from the
supercharging sensor and determines the amount of fuel to inject, acting on the fuel pressure regulator
and the injector opening times.
In addition, the control unit controls the opening of the turbocharger waste gate valve, via the solenoid
valve, in order to ensure excellent performance in all operating conditions.
Control of throttle closing when engine is switched off
When the engine is switched off (ignition key in OFF position) the injection control unit closes the throt­
tle valve located on the air intake duct via the special solenoid valve.
This action makes it possible to limit the tiresome shuddering of the engine whilst it is switching off.
6 .i. V!-01-.Cancelftand replaces Print n° 506.763/25

Marea- Marea Weekend 9 ™
2000 range ©
Engine
Fuel feed system
10.
DIAGRAM SHOWING INFORMATION FLOW BETWEN THE INJECTION CONTROL UNIT AND
SENSORS/ACTUATORS
1. Auxiliary fuel pump
2. Variable geometry turbocharger control sole­
noid
3. Climate control compressor
4. Electric EGR valve
5. Rev counter
6. Engine radiator fan
7. Glow plug preheating control unit
8. Potentiometer on accelerator pedal
9. Brake and clutch pedal switches
10. Fuel pressure sensor
11. Intake air flow and temperature sensor (de-
bimeter)
12. Coolant temperature sensor
13. Fuel temperature sensor
14. Pressure relief sensor
15. Timing sensor
16. Rpm sensor
17. Vehicle speed signal
18. Battery
19. Four stage pressure switch
20. Fiat CODE control unit
21. Diagnostic socket
22. Fuel pressure regulator
23. Injectors
24. Throttle valve control solenoid
25. Glow plug preheating warning light
26. Injection system failure warning light
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Marea- Marea Weekend 9 ™
2000 range ©) Fuel feed system
Engine
10.
Compents of injection system wiring diagram
1. Vehicle speepd
2. Rev counter
3. Engine radiator fan low speed relay
4. Radiator fan high speed activation relay
5. Potentiometer on accelerator pedal
6. Timing sensor
7. Fuel pressure sensor
8. EGR system modulator solenoid
9. Fuel pressure regulator
10. Glow plug preheating warning light on control panel
11. Injection system failure warning light
12. Air conditioning system relay
13. Coolant temperature sensor
14. Rpm sensor
15. Fuel temperature sensor
16. Diagnostic socket
17. Fiat CODE control unit
18. Four stage pressure switch
19. Injection electronic control unit
20. Pressure relief sensor
21. 7.5A fuse protecting electronic injection system ( + 15 power supply from ignition switch)
22. 7.5A fuse protecting electronic injection system ( + 30 power supply from ignition switch)
23. Main injection system relay
24. 30A fuse protecting injection system
25. Auxiliary fuel pump relay
26. Glow plug preheating control unit
27. Intake air flow and temperature sensor (debimeter)
28. Brake pedal switch
29. Clutch pedal switch
30. Ignition switch
31. Battery
32. Inertia switch
33. Auxiliary fuel pump (submerged in tank)
34. 60A fuse protecting glow plug control unit
35. Cylinder no. 1 glow plug
36. Cylinder no. 2 glow plug
37. Cylinder no. 3 glow plug
38. Cylinder no. 4 glow plug
39. Cylinder no. 1 injector
40. Cylinder no. 2 injector
41. Cylinder no. 3 injector
42. Cylinder no. 4 injector
43. Throttle valve control solenoid
44. Variable geometry turbocharger control solenoid
45. Diesel filter heater relay
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Ma tea- Ma tea Weekend !@ ™
2000 range ©
Engine
Fuel feed system
10.
37 Not connected
38 Not connected
39 Not connected
40 Not connected
41 Not connected
42 Not connected
43 Not connected
44 Not connected
45 Not connected
46 Not connected
47 Engine rpm signal output
48 Diagnostic line k
49 Vehicle speed signal input
50 Not connected
51 Activation signal from 4-stage pressure switch
52 Activation signal from 3-stage pressure switch
53 Not connected
54 Not connected
55 Not connected
56 Not connected
57 Not connected
58 Key ON signal
59 Brake switch
60 Air conditioner activation request
61 Clutch switch
62 Glow plug diagnosis
63 Not connected
64 Not connected
65 Not connected
66 Not connected
67 Not connected
68 Not connected
69 Not connected
70 Not connected
71 Not connected
72 Not connected
73 Not connected
74 Not connected
75 Not connected
76 Accelerator pedal 1 earth
77 Accelerator pedal 1 signal
78 Accelerator pedal 1 power supply
79 Accelerator pedal 2 earth
80 Accelerator pedal 2 signal
81 Accelerator pedal 2 power supply
82 Diesel temperature sensor (pin 1)
83 Diesel temperature sensor (pin 2)
84 Coolant temperature sensor (pin 1)
85 Coolant temperature sensor (pin 2)
86 Air flow meter (pin 1)
87 Not connected
88 Air flow meter (pin 3)
89 Air flow meter (pin 5)
90 Fuel pressure sensor (pin 3)
91 Fuel pressure sensor (pin 2)
92 Fuel pressure sensor (pin 1)
93 Turbo pressure sensor (pin 1)
94 Turbo pressure sensor (pin 3)
95 Turbo pressure sensor (pin 2)
96 Not connected
97 Air flow meter (pin 4)
98 Not connected
99 RPM sensor (pin 1)
100 RPM sensor (pin 2)
101 RPM sensor (pin 3)
102 RPM sensor (pin 1)
103 Timing sensor (pin 2)
104 Timing sensor (pin 3)
105 Not connected
106 Not connected
107 Not connected
108 Fuel pressure regulator
109 Fuel pressure regulator
110 Not connected
111 Heater relay control Fuel filter
112 Not connected
113 Not connected
114 Cylinder 4 injector control
115 Not connected
116 Not connected
117 Cylinder 1 and 2 injector power supply
118 Cylinder 3 and 4 injector power supply
119 Cylinder 1 injector control
120 Cylinder 2 injector control
121 Cylinder 3 injector control
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Marea- Marea Weekend 9"°
2000 range ©
Engine
Fuel feed system
10.
TIMING SENSOR
The Hall effect sensor is fitted to the cylinder head and faces the camshaft pulley.
An opening on the pulley allows the timing sensor to detect the engine timing position and indicate it to
the injection control unit.
The injection control unit uses the timing sensor signal to detect TDC at the end of compression.
Operation
A semi-condulator layer, through which a current passes, immersed in a magnetic field (lines of force per­
pendicular to the direction of the current), produces a difference in power, known as Hall voltage.
If the intensity of the current remains constant, the voltage produced only depends on the intensity of the
magnetic field. The intensity of the field can simply be altered periodically to produce a modulated electri­
cal signal. Signal frequency is proportional to the speed with which the magnetic field changes.
To achieve this change, the sensor is crossed by a metal ring (inner part of the pulley) with an opening.
When it moves, the metal part of the ring covers the sensor to magnetic field and the output signal is
therefore low; Conversely, the sensor generates a high signal at the opening when the magnetic field is
present.
This signal, together with the rpm and TDC signals, allows the injection control unit to identify piston po­
sition and determine injection point.
AIR FLOW METER
(DEBIMETER)
The debimeter is located on the air intake
sleeve and is hot film type.
The debimeter contains an intake air tem­
perature sensor.
Operation
The principle of operation is based on a
heated membrane fitted into a measurement
channel through which engine intake air
flows.
The hot film membrane is maintained at a
constant temperature (about 120 °C higher
than incoming air) by the heater coil.
The mass of air flowing through the measure­
ment channel tends to take heat from the
membrane. To keep the membrane at constant
temperature, a certain current level must flow
through the resistance.
Because this current is proportional to the
mass of air that flows to the engine, it can be
measured with a Wheatstone bridge and the
resulting signal is sent to the injection control
unit.
1. Covers
2. Electronic card
3. Sensor
4. Mounting plate
5. Mount
6. o-ring
7. Temperature sensor
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