Page 379 of 1336
Engine room
relay box
E-EGR valve
Cooling fan
E-EGR cooler
bypass valveE-VGT
actuator
IMV
Throttle posi.
sensor
InjectorA/C
compressorStart motor
Variable swirl
valve
(3) Components for ECU Input
PTC heater
CAN
- Glow plug unit
- ABS & ESP unit
- BCM
- E-coupling unit
- EPS
- GCU
- Meter cluster
- SKM
- TCU
- Self diagnosis
Page 380 of 1336

0000-00
2) ECU Control
(1) Function
a. ECU Function
ECU receives and analyzes signals from various sensors and then modifies those signals into
permissible voltage levels and analyzes to control respective actuators.
ECU microprocessor calculates injection period and injection timing proper for engine piston speed and
crankshaft angle based on input data and stored specific map to control the engine power and emission
gas.
Output signal of the ECU microprocessor drives pressure control valve to control the rail pressure and
activates injector solenoid valve to control the fuel injection period and injection timing; so controls
various actuators in response to engine changes. Auxiliary function of ECU has adopted to reduce
emission gas, improve fuel economy and enhance safety, comforts and conveniences. For example,
there are EGR, booster pressure control, autocruise (export only) and immobilizer and adopted CAN
communication to exchange data among electrical systems (automatic T/M and brake system) in the
vehicle fluently. And Scanner can be used to diagnose vehicle status and defectives.
water and electromagnetism and there should be no mechanical shocks.
To control the fuel volume precisely under repeated injections, high current should be applied instantly
so there is injector drive circuit in the ECU to generate necessary current during injector drive stages.
Current control circuit divides current applying time (injection time) into full-in-current-phase and hold-
current-phase and then the injectors should work very correctly under every working condition.
b. Control Function
Controls by operating stages
To make optimum combustion under every operating stage, ECU should calculate proper injection
volume in each stage by considering various factors.
Starting injection volume control
During initial starting, injecting fuel volume will be calculated by function of temperature and engine
cranking speed. Starting injection continues from when the ignition switch is turned to ignition
position to till the engine reaches to allowable minimum speed.
Driving mode control
If the vehicle runs normally, fuel injection volume will be calculated by accelerator pedal travel and
engine rpm and the drive map will be used to match the drivers inputs with optimum engine power. -
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Page 381 of 1336

(2) Fuel Control
a. Fuel Pressure Control Elements
Pressure control consists of 2 principles.
Determines rail pressure according to engine operating conditions.
Controls IMV to make the rail pressure to reach to the required value. -
-
Pressure in the fuel rail is determined according to engine speed and load on the engine.
When engine speed and load are high
The degree of turbulence is very great and the fuel can be injected at very high pressure in order to
optimize combustion.
When engine speed and load are low
The degree of turbulence is low. If injection pressure is too high, the nozzle's penetration will be
excessive and part of the fuel will be sprayed directly onto the sides of the cylinder, causing
incomplete combustion. So there occurs smoke and damages engine durability. -
-
Fuel pressure is corrected according to air temperature, coolant temperature and atmospheric pressure
and to take account of the added ignition time caused by cold running or by high altitude driving. A
special pressure demand is necessary in order to obtain the additional flow required during starts. This
demand is determined according to injected fuel and coolant temperature.
b. Fuel Pressure Control
Open loop determines the current which needs to be sent to the actuator in order to obtain the flow
demanded by the ECU.
Closed loop will correct the current value depending on the difference between the pressure demand
and the pressure measured.
If the pressure is lower than the demand, current is reduced so that the fuel sent to the high pressure
pump is increased.
If the pressure is higher than the demand, current is increased so that the fuel sent to the high
pressure pump is reduced. -
-
Rail pressure is controlled by closed loop regulation of IMV.
Page 393 of 1336

Load Engine speed Swirl
valveAmount of
swirlRemarks
Low speed,
Low loadbelow 3,000 rpm Closed HeavyIncreased EGR ratio, better air-fuel
mixture (reduce exhaust gas)
High speed,
High loadover 3,000 rpm Open LightIncrease charge efficiency, higher
engine power
The variable swirl valve actuator operates when
turning the ignition switch ON/OFF position to
open/close the swirl valve. In this period, the soot
will be removed and the learning for swirl valve
position is performed.
Swirl valve
Swirl: This is the twisted (radial) air flow along the cylinder wall during the intake stroke. This stabilizes
the combustion even in lean air-fuel mixture condition.
e. Features
Swirl and air intake efficiency
To generate the swirl, the intake port should be serpentine design. This makes the resistance in air
flow. The resistance in air flow in engine high speed decreases the intake efficiency. Eventually, the
engine power is also decreased, Thus, the swirl operation is deactivated in high speed range to
increase the intake efficiency.
Relationship between swirl and fuel injection pressure
The injector for DI engine uses the multi hole design. For this vehicle, there are 8 holes in injector. If
the swirl is too strong, the injection angles might be overlapped and may cause the increased PM and
insufficient engine power. Also, if the injection pressure is too high during strong swirl, the injection
angles might be overlapped. Therefore, the system may decreases the fuel injection pressure when
the swirl is too strong. -
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Page 395 of 1336
T-MAP sensor
D20DTF ECUOxygen sensor
Electronic
throttle bodyHFM sensor
(intake air temp.)
Coolant
temp.sensor
E-EGR valve
Crankshaft posi.
sensor
Accelerator
pedal
E-EGR cooler
(5) EGR control
a. Overview
The EGR (Electric-Exhaust Gas Recirculation) valve reduces the NOx emission level by recirculating
some of the exhaust gas to the intake system.
The major difference with the previous EURO 4 type, is that the DC motor with improved response rate
according to the EURO 5 regulation. The solenoid type actuator is used in the conventional model, but in
this new model, the DC motor type actuator with improved response rate is adopted. Also the hall senso
r
which provides a more stabilized signal than the potentiometer, and the EGR bypass flap which
improves engine warming up efficiency are also used. The HFM sensor and the position sensor are
used to feedback the amount of EGR for both EURO 4 and EURO 5.
b. Components
Page 399 of 1336
Accelerator
pedalE-VGT
actuator
Coolant
temperature
Front EGT
sensorT-MAP sensorCrankshaft pos,
sensor
HFM sensor
(intake air temp)
ECU
(D20DTF)
(6) 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
Page 401 of 1336
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 563 of 1336

1490-00
3. ECU CONTROL
1) Functions
ECU receives and analyzes signals from various sensors and then modifies those signals into
permissible voltage levels and analyzes to control respective actuators.
ECU microprocessor calculates injection period and injection timing proper for engine piston speed and
crankshaft angle based on input data and stored specific map to control the engine power and emission
gas.
Output signal of the ECU microprocessor activates the injector solenoid valve to control the fuel injection
period and injection timing; so controls various actuators in response to engine changes.
Auxiliary function of ECU has adopted to reduce emission gas, improve fuel economy and enhance
safety, comforts and conveniences. For example, there are autocruise and immobilizer and adopted
CAN communication to exchange data among electrical systems (automatic T/M and brake system) in
the vehicle fluently. And the diagnostic tool can be used to diagnose vehicle status and defectives.
water and electromagnetism and there should be no mechanical shocks.
2) Control Functions
Controls by operating stages:
To make optimum combustion under every operating stage, ECU should calculate proper injection
volume in each stage by considering various factors.
Starting injection volume control:
During initial starting, injecting fuel volume will be calculated by function of temperature and engine
cranking speed. Starting injection continues from when the ignition switch is turned to ignition
position to till the engine reaches to allowable minimum speed.
Driving mode control:
If the vehicle runs normally, fuel injection volume will be calculated by accelerator pedal travel and
engine rpm and the drive map will be used to match the drivers inputs with optimum engine power. -
-
-