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Fuel rail assembly
Relieves the pulsation.
Measures the fuel pressure.
Distributes the fuel to injectors.Camshaft position sensor
Determines the injection order.
Injector (C3I)
Pre-injection, main injection, after-injection by
signals from ECU
Fuel tank
Fuel metering by dual sender. Supply the fuel in
main fuel tank and sub fuel tank through fuel
inlet tube
2. SYSTEM LAYOUT AND OPERATION
1) Layout
Fuel supply line
Fuel return line
For sensor and actuator control logic,
refer to Chapter "ENGINE CONTROL".
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Crankshaft position sensor
Measuring engine rpmT-MAP sensor
Measuring booster pressure
and temperatureHFM
Measuring intake air mass and
temperature
Engine ECU (D20DTF)
Engine control by various
signals
High pressure pump
Generates the high pressurized fuel
and supply it.
Plunger type HP pump (1,800
bar)
Vane type transfer pump (6bar)
Accelerator pedal
position sensor
Detects driver's intention for
speed up/downFuel filter assembly
Supply clean fuel/fuel
heating/water separation by
priming pump
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2) Fuel System Flow Diagram
The fuel from the fuel tank is supplied to the fuel heater of fuel filter/priming pump and then low pressure
generated by the low pressure pump (built into HP pump) is transmitted to the HP pump.
The fuel pressure at the HP pump is controlled by the IMV valve, and the maximum allowed pressure is
1,800 bar. The compressed fuel at the fuel pump is delivered to the rail, and injected by the injectors
according to the injection signals. The injection method is the same with the conventional method; Fuel
return by backleak which operates the needle valve.
The major difference is that the fuel return line is connected to the fuel filter inlet port, not the HP pump
venturi.
The pressure from the high pressure pump is increased to 1,800 bar from 1,600 bar, and the pump is now
installed to the cylinder head (cylinder block for previous model). The fuel pressure is generated by the
operation of intake camshaft and gears. The specifications for the IMV valve and the fuel temperature
sensor are not changed.
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3) Input/Output devices
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The engine ECU calculates the accelerator pedal based on the input signals from various sensors, and
controls the overall operation of the vehicle.
The ECU receives the signals from various sensor through data line, and performs effective air-fuel ratio
control based on these signals.
The crankshaft speed (position) sensor measures the engine speed, and the camshaft speed (position)
sensor determines the order of injections, and the ECU detects the amount of the accelerator pedal
depressed (driver's will) by receiving the electrical signals from the accelerator pedal sensor.
The mass air flow sensor detects the volume of intake air and sends the value to the ECU.
The major function of the ECU is controlling air-fuel ratio to reduce the emission level (EGR valve control)
by detecting instantaneous air flow change with the signals from the mass air flow sensor.
Also, the ECU uses the signals from the coolant temperature & air temperature sensors, booster pressure
sensor, atmospheric pressure sensor to: a) determine injection starting point and set value for pilot
injection, and b) deal with various operations and variable conditions.
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4) Flow Diagram of Fuel Supply System
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