Page 188 of 600
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Turbocharger intercooler
4. LAYOUT OF INTAKE SYSTEM
HFM sensor (HFM 6.0)
Turbocharger
Supplying the compressed air by turbocharger
Air cleaner
Turbocharger
Turbocharger
Plug in sensor
Air
cleanerTurbochargerProtension graph
Temperature
sensor
Air cleaner
Intake manifold
Coolant port To respective cylinder
From
intercoolerVGT control
actuator
Exhaust gas
Throttle body
Engine operating: Flap
openEngine stopped:
Flap closed
Intake duct
Intake duct
Boost pressure
sensor
Power
Voltage outputGround
Page 205 of 600

4. CAUTION WHEN SERVICING THE ENGINE
1) Cleaness
Engine has a lot of precisely machined (grinding, polishing, lapping) surfaces. Thus, there should be
great cautions for cleaness when servicing the engine components. Apply the engine oil on the sliding
surfaces when assemblying the components. Every component should be disassembled and
reassembled in accordance with the correct sequences. Before servicing the engine, the negative cable
should be diconnected from the battery. Otherwise, some electric or electronic components could be
damaged.
2) Servicing
Before service work, be sure to disconnect battery negative (-) terminal to prevent damages by bad
wire and short.
To prevent the foreign material from getting into engine cylinder, cover the inlet of air cleaner if the
air cleaner has been removed.
(1) Lifting up the vehicle
Always keep the safety precautions.
To prevent the vehicle from rolling down, put the chocks under the tires (when using a 4-post lift).
Make sure to support the correct lifting points (when using a 2-post lift) -
-
-
(2) Exhaust system
Wear the safety glove when removing the exhaust pipe.
Make sure that the exhaust pipe is cooled before removing it. -
-
(3) Cautions before service
Scalding hot coolant and steam could be blown out under pressure, which could cause serious injury.
Never remove the coolant reservoir cap when the engine and radiator are hot.
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D20DT Engine Remarks
To enhance the EGR performance by
making the temperature of exhaust
gas into the intake manifold down, the
EGR cooler has been introduced. *EGR cooler
EGR GasCoolant
The throttle body and boost pressure
sensor have been installed on the
intake manifold. *
Intake manifold
Throttle
bodyBoost pressure sensor
Cylinder head
Coolant portTo enhance the cooling performance,
the coolant port has been introduced. *
To enhance the cooling performance,
the coolant passage has been made
in the cylinder block. *
Cylinder head gasket
Coolant passage
Page 212 of 600

1. FUEL FLOW OF D20DT (EURO 4) ENGINE
According to input signals from various sensors, engine ECU calculates driver's demand (position of the
accelerator pedal) and then controls overall operating performance of engine and vehicle on that time. ECU
receives the signals from sensors via data line and then performs effective engine air-fuel ratio controls
based on those signals. Engine speed is measured by crankshaft speed (position) sensor and camshaft
speed (position) sensor determines injection order and ECU detects driver's pedal position (driver's
demand) through electrical signal that is generated by variable resistance changes in accelerator pedal
sensor. HFM (Hot Film Air Mass) sensor detects intake air volume and sends the signals to ECU.
Especially, the engine ECU controls the air-fuel ratio by recognizing instant air volume changes from air flow
sensor to decrease the emissions (EGR valve control). Furthermore, ECU uses signals from coolant
temperature sensor and air temperature sensor, booster pressure sensor and atmospheric pressure sensor
as compensation signal to respond to injection starting, pilot injection set values, various operations and
variables.
Page 217 of 600
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Intercooler
Booster Pressure SensorIntake Manifold
Ground Supply power
Output
voltageTo corresponding
cylinders Coolant
port
Compressed
air
EGR gas
Engine stopped:
flap closed Normal: flap open
Intake duct
Intake duct
Intake manifold
(Throttle body)
Turbo charger
Throttle body
Page 238 of 600
1. COMPARISON IN COOLING SYSTEM FOR EACH ENGINE
For the D20DT (EURO4) engine, the cooling system is equipped with E-EGR cooler and the water pump
which its capacity is improved according to the additional coolant line in the cylinder block.
Page 239 of 600
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Coolant Flow in Engine
2. SCHEMATIC DIAGRAM
Cylinder block side
Cylinder head side
-
-
Page 244 of 600

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2. OPERATION
Glow plug is installed in the cylinder head. It enhances the cold starting performance and reduces the
exhaust gas during cold starting.
1. Pre-heating
2. Post-heating during engine running If normal communication with the ECU is established 2 seconds after the power is supplied to the IGN
terminal from the battery, the ECU supplies the battery voltage to glow plugs.
The post-heating controlled by ECU begins its operation after engine start The time for pre-heating is controlled by the ECU. -
The time for post-heating controlled by the ECU starts from engine start. This improves the idling
conditions and reduces the emission and noise. -
2) System Check
Glow Plug
Forced Shut-off of Relay
Check for short in each glow plug
Check for open due to over-voltage in each glow plug
Check for open to ground in glow plug -
-
-
When the glow plug circuit is open to ground. -
1) Operation
Pre-
heatingCoolant
temperature
Operating time 31s 22s 19s 17s 14s 0s 0s
Operating
conditions- IGN: ON
- B+: below 15.2 VStop
conditions- Time-out
- IGN: OFF
- when engine cranking
Post-
heatingCoolant
temperature
Operating time 115s 80s 30s 19s 11s 11s 0s
Operating
conditions- after engine start Stop
conditions-Time-out
- Torque: 190/170Nm
- rpm: 2100/2050