Page 359 of 796
15-310000-00
F. Features
As EGR ratio goes up, smoke volume will be
higher. But, this lowers the combustion
chamber temperature and accordingly the
concentration of NOx is decreased. The point
with highest NOx is immediately after TDC.As EGR temperature goes up, the
concentration of NOx will be higher. Thus, it is
necessary to cool down the exhaust gas.
However, during engine cooled, it may cause
large amount of PM. To prevent this, the
exhaust gas is bypassed the EGR cooler.
Page 360 of 796
15-32
(10) E-VGT control
A. Overview
E-VGT (Electric-Variable Geometry Turbine) turbocharger system in D20DTR engine uses the venturi
effect that controls the flow rate of exhaust gas by adjusting the passage in turbine housing. The newly
adopted DC motor actuator (E-actuator) controls the E-VGT system more precisely and faster. To get
the high operating power from turbine, the ECU reduces the exhaust gas passage In low speed range
and increases it in high speed range.
B. Components
HFM (intake air
temperature)
Front EGT
sensor
E-VGT actuatorAccelerator pedal
module
Crankshaft
position
sensorOxygen sensor
T-MAP sensor
Coolant
temperature
sensor
D20DTR ECU
Page 362 of 796
15-34
D. E-VGT system control
Turbocharger system operates the E-VGT actuator according to the signals for engine epm,
accelerator pedal position, atmospheric pressure, T-MAP, coolant temperature and intake air
temperature.
Turbocharger actuator is performed PWM control by ECU.
In general, the boost pressure feedbacks the turbocharger operation and the boost temperature is
used for calculating the precise density.
E-VGT provides higher engine power with faster reaction speed compared to conventional VGT.
Operating wave Vane Control
Low
speed
rangeIn low speed range:
retract the vane to
increase boost
pressure. The vane
has low (-) duty, and
the unison ring
moves to retract the
vane in weak PWM
signal.
High
speed
rangeThe unison ring
moves to extend the
vane in strong PWM
signal. Maximum
pressure is 3 bar and
the system controls it
according to the inpu
t
signals.
Page 363 of 796
15-350000-00
HFM (intake air
temperature)CDPF
Electric throttle
bodyCoolant
temperature
sensorOxygen sensor
Injector (C3I)
E-EGR valve
(11) Wide band oxygen sensor control
A. Overview
For diesel engine, combustion is not performed at the optimum (theoretically correct) air-fuel ratio and
the oxygen concentration is thin in most cases. So the wide-band oxygen sensor is used for this kind o
f
engine, and this sensor is a little different from the one that used for gasoline engine. The combustion
in diesel engine is controlled by fuel injection volume. Therefore, the wide band oxygen sensor should
be used in diesel engine. This sensor measures the air-fuel ratio in very wide range, and is also called
full range oxygen sensor.
The wide band oxygen sensor measures the oxygen density in exhaust gas and sends it to ECU
to control the EGR more precisely. -
B. Components
D20DTR ECU
Page 366 of 796

15-38
Relay box
A/C
compressorHFM (intake air
temperature)Cooling fan
module
MB 5 A/T (ATF
temperature)Coolant
temperature
sensor
(12) Cooling fan control
A. Overview of cooling fan and A/C compressor
The cooling system maintains the engine temperature at an efficient level during all engine operating
conditions. The water pump draws the coolant from the radiator. The coolant then circulates through
water jackets in the engine block, the intake manifold, and the cylinder head. When the coolant
reaches the operating temperature of the thermostat, the thermostat opens. The coolant then goes
back to the radiator where it cools. The heat from automatic transmission is also cooled down through
the radiator by circulating the oil through the oil pump. ECU controls the electric cooling fans with three
cooling fan relays to improve the engine torque and air conditioning performance.
For detailed information, refer to Chapter "Air Conditioning System".
B. Components
D20DTR ECU
Refrigerant
Page 368 of 796

15-40
D. Cooling fan and A/C compressor control
Conditions for cooling fan control ▶
The PWM cooling fan is set by coolant temperature and A/C refrigerant pressure. And, the setting
value in A/T equipped vehicle may vary according to the internal oil temperature. The The engine ECU
controls the PWM cooling fan unit based on various signals to get the optimized temperature during
engine running.
PWM cooling fan control according to coolant temperature and vehicle speed -
The PWM cooling fan starts running
from 89℃ of coolant temperature
PWM cooling fan control according to transmission fluid temperature (A/T)
1. PWM duty under 129℃: 0%
2. PWM duty over 130℃: 94.4% -
PWM cooling fan control according to A/C refrigerant pressure -
PWM duty value sharply increases
when the A/C refrigerant pressure
goes over 10 bar. And, it slowly
decreases when A/C refrigerant
pressure goes down below 14 bar
(A/C compressor OFF). PWM duty
Refrigerant
pressure (bar)under 101℃: The PWM dut
y value
decreases when the vehicle speed
increases
over 105℃: The PWM duty value
is fixed at 94.4% -
-
Page 369 of 796
15-410000-00
A/C compressor OFF conditions ▶
Coolant tem
perature: below -20℃ or over
115℃
Engine rpm: over 4500 rpm
Engine rpm: below 600 rpm
When abrupt acceleration
Very high load during idling
Refrigerant pressure: over 32 bar or below 2
bar
Failure in refrigerant sensor, coolant
temperature sensor, and cooling fan -
-
-
-
-
-
-
Page 370 of 796
15-42
PTC Fuse and Relay
(13) PTC heater control
A. Overview
The supplementary electrical heater is installed in DI engine equipped vehicle as a basic equipment.
The PTC system is operated according to two temperature values measured at the coolant temperature
sensor and HFM sensor. This device is mounted in the heater air outlet and increase the temperature of
air to the passenger compartment. Because PTC system is heated by electrical power, high capacity
alternator is required. PTC does not operate during engine cranking, while the battery voltage is lower
than 11 V or during preheating process of glow plugs.
B. Components
HFM (intake air
temperature)
Coolant temperature
sensor
PTC relay 1
D20DTR ECU
PTC relay 2
PTC fuse 1, 2, 3, 40A
PTC heater