Page 333 of 828
15-30
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 334 of 828
15-310000-00
(10) E-VGT control
A. Overview
E-VGT (Electric-Variable Geometry Turbine) turbocharger system in D20DTF 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
sensor
Oxygen sensor
T-MAP sensor
Coolant
temperature senso
r
D20DTR ECU
Page 336 of 828
15-330000-00
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 input signals.
Page 337 of 828
15-34
HFM (intake air
temperature)CDPF
Electric throttle
bodyCoolant
temperature senso
r
Oxygen 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 of 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 340 of 828

15-370000-00
HFM (intake air
temperature)Cooling fan module
DSI 6 A/T (ATF
temperature)Coolant
temperature senso
r
Refrigerant
pressure sensor
Relay box
(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
A/C compressor
D20DTR ECU
Page 342 of 828

15-390000-00
D. Cooling fan and A/C compressor control
Conditions for cooling fan ▶
The cooling fan module controls the cooling fan relay, high speed relay and low speed relay. The
cooling fan is controlled by the series and parallel circuits.
A/C switch Cooling fanCoolant temperature Refrigerant pressure
A/C compressor
OFF OFF Coolant temp. < 90℃ -
LO 90℃ ≤ Coolant temp.
< 105℃-
HI 105℃ ≤ Coolant temp. -
ONLO
Coolant temp. < 105℃Refrigerant pressure <
18 bar
ON
HI 18 bar ≤ Refrigerant
pressure
HI 105℃ ≤ Coolant tem
p.
< 115℃-
HI115℃ ≤ Coolant temp. -
OFF (cut)
A/C compressor OFF conditions ▶
Coolant temperature: below -20℃ or over
115℃
Approx. 4 seconds after starting the engine
Engine rpm: below 650 rpm or over 4500 rpm
When abrupt acceleration
Refrigerant pressure:
* OFF below 2.0 kg/㎠, then ON over 2.4 kg/㎠
* OFF over 30 kg/㎠, then ON below 21.4 kg/㎠ -
-
-
-
-
The output voltage from refrigerant pressure sensor is 1.7 V to 3.5 V when the refrigerant pressure
is 10 to 24 kgf/㎠ with A/C "ON".Output voltage according to refrigerant pressure ▶
Cooling fan controls according to ATF ▶
ATF temperature Fan condition Remark
Over 110˚CHigh speed -
Page 343 of 828
15-40
Relay box in engine compartment
(13) High speed
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
sensorPTC heater
PTC 2 relay (PTC
heater 2, 3)
PTC heater
3 (40A)
PTC heater
2 (40A)
PTC heater
1 (40A)
D20DTR ECU
PTC 1 relay
(PTC heater 1)
Page 345 of 828
15-42
D. Control conditions
Operation Operating condition PTC Heater
HI
(PTC2)- Coolant temperature < 15℃PTC HI ON
LO
(PTC1)- Coolant temperature 15℃ ≤ 65℃, intake air
temperature ≤ -10℃
- Coolant temperature 15℃ < 65 to 60℃, intake air
temperature <-10℃ to 0℃
- Coolant temperature 15℃ ≤ 60℃, intake air
temperature ≤ 0℃ to 5℃PTC LO ON
Stop- A/C blower switch OFF
- Defective ambient air temperature sensor
(including open or short circuit)
- Engine cranking
- Low battery voltage (below 11V)
- During pre-glow process (glow indicator ON)
Operation diagram for PTC heater LO (step 2) ▶