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03-212210-01
1. OVERVIEW
The components in fuel system supply the fuel and generate the high pressure to inject the fuel to each
injector. They are controlled by the engine ECU.
The common rail fuel injection system consists of fuel tank, fuel line, low pressure line which supplies lo
w
pressure fuel to the low pressure pump (including high pressure pump), common rail which distributes
and accumulates the high pressurized fuel from the fuel pump, high pressure line which connected to
the injector, and the engine control unit (ECU) which calculates the accelerator pedal position and
controls the overall performance of vehicle based on the input signals from various sensors.
1) Fuel Flow Diagram
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03-22
2. SYSTEM LAYOUT AND OPERATION
1) Layout
For sensor and actuator control logic, refer to Chapter "Engine Control".
Engine ECU (D20DTR)
Engine control by various
signalsFuel tank
Fuel metering by sender
HFM sensor
Measuring intake air mass and
temperature
Crankshaft position sensor
Measuring engine rpmInjector (C3I)
Pre-injection, main injection,
after-injection by signals from
ECUCamshaft position sensor
Determining injection order
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03-232210-01
Accelerator pedal position
sensor
Detecting driver's intention
for speed up/down
Fuel rail assembly
Relieving the pulsation.
Measuring the fuel pressure.
Distributing the fuel to injectors.
Fuel filter assembly
Supplying clean fuel/fuel
heating/water separation by
priming pump
Plunger type HP pump (1,800 bar)
Vane type LP pump (6 bar)
T-MAP sensor
Measuring booster pressure
and temperature
High pressure pump
Generating high pressurized fuel and
supplying it according to engine rpm,
required volume, required pressure
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03-252210-01
3) Input/Output devices
Refer to Chapter "Engine Control". *
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03-26
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.
Page 105 of 751

04-4
2. INSPECTION
1) Troubleshooting
When Abnormal Noises are Heard from the Engine Room ▶
For the vehicle equipped with DI engine, if a learning noise occurs in each range or other noises
occur, the major cause of it is a faulty turbocharger assembly. But an interference issue, poor
tightness or loose in the intake and exhaust system also can cause those noises. This is mainly
because the operator didn't follow the instruction exactly when reconnecting the intake hoses and
pipes which were disconnected to check the system or replace the air cleaner. If the intake system is
free of any faults, check the EGR and PCV oil separator connected to the intake system.
The figure may be different from the actual engine. Therefore, read thoroughly below before replacing
the parts.
2) Abnormal Noise Caused by Poor Tightness of Intake System
When the DI engine is running, the air entered into the engine flows in the sequence as shown above. If
high intake pressure is applied to the loose or damaged part, a whistling noise may occur, the intake air
volume is measured incorrectly or the engine power is derated.
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04-51719-00
3) Troubleshooting Sequence
The basic checks for intake system are as follows:
Basic Checks for Intake System ▶
Make sure to replace or clean the air cleaner
element periodically. Otherwise, engine will be
derated or work abnormally because of low
intake air volume.
Unlike the fuel system, which is a closed
circuit, the intake system is an open circuit
system. Therefore any malfunction may occur
due to dust and dirt.
Most of the connections consist of hoses so
the system cannot withstand high temperature
and pressure. Also it can be deformed or
loosened easily because it is a clamp
mounting system. Thus, when checking the
engine, basic inspections, such as tightened
status check and visual inspection for hose,
etc., should be carried out in advance.
Other Checks for Intake System ▶
If the intake system is free of any faults, check
for EGR and PCV oil separator.
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04-6
1. OVERVIEW
The intake system for D20DTR engine is equipped with a throttle body which includes a flap. This flap is
controlled by an electrical signal to cut off the intake air entering to the engine when the ignition switch is
turned off. Because of this, the shape of the intake manifold has been changed and improved HFM
sensor is newly adopted to control the intake air volume more precisely.
2. COMPONENT
2330-01 Intercooler assembly
2313-15 HFM sensor
HFM sensor, version 6
*For more information, refer to Chapter "Engine
Control".
2313-01 Air cleaner assembly