ECU SSANGYONG NEW REXTON 2012 Workshop Manual

(8) Swirl control
A. Overview
Variable swirl valve
The strong swirl caused by intake air is important element for anti-locking function in diesel engine. The
swirl control valve partially closes the intake port to generate the swirl according to the engine conditions.
When the engine load is in low or medium range, the swirl could not be generated because the air flow is
slow. To generate strong swirl, there are two passages in intake manifold, and one of them has the valve
to open and close the passage. When the valve closes the passage, the air flow through the another
passage will be faster, and the strong swirl will be generated by the internal structure of the passage. This
swirl makes the better mixture of air and fuel, eventually the combustion efficiency in combustion
chamber could be improved. This provides the enhanced fuel consumption, power and EGR ratio.
Components
HFMCrankshaft position sensorVariable swirl valve
Coolant temperature
sensorAccekerator pedal
moduleD20DTR ECU

(9) 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.
To meet Euro-V regulation, the capacity and response rate of E-EGR valve in D20DTR engine have
been greatly improved. The EGR cooler with high capacity reduces the Nox, and the bypass valve
reduces the CO and HC due to EGR gas before warming up.
Also, the engine ECU adjusts the E-EGR opening by using the air mass signal through HFM sensor. If
the exhaust gas gets into the intake manifold when the EGR valve is open, the amount of fresh air
through HFM sensor should be decresed.
B. Components
E-EGR cooler
Accelerator pedal
moduleD20DTR
ECU
Coolant
temperature
sensorOxygen sensor
HFM (intake air
temperature)Electric throttle
body
Crankshaft
position
sensorE-EGR valve
T-MAP
sensor

D. Bypass control for EGR cooler
Cooler temperature
Exhaust gas temperature
Otherwise, PM could be increased due to too low exhaust gas temperature.
E. Control elements for EGR system
Accelerator pedal (engine load) - Indicates the driver's intention and engine load. If the load goes up,
the EGR ratio is decreased.
T-MAP (boost pressure map stored in ECU) - Compensates the difference in boost pressure by
adjusting EGR ratio.
Engine rpm - Used as the signal for determining EGR operating range.
Coolant temperature - When the coolant temperature is low, NOx is decreased but PM could be
increased. So, to reduce PM, decrease EGR ratio when the coolant temperature is low.
Intake air mass and temperature - HFM sensor measures the intake air mass to calculate the actual
EGR volume. If the air mass is larger than programmed value in map, EGR ratio will be higher.
EGR position sensor - Detects the actual opening angle of EGR valve and performs feedback
function according to PWM control by ECU.
Wide band oxygen sensor - Detects the oxygen volume in exhaust gas to check if the EGR ratio is
proper.
Electronic throttle body - Keeps EGR ratio to optimized level by controlling the throttle body in EGR
operating range (decreasing pressure in intake manifold). -
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(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)E-VGT actuatorAccelerator pedal
module
Crankshaft
position sensorOxygen sensor
T-MAP sensor
Coolant
temperature
sensor
D20DTR ECU
Front EGT sensor

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.

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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 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

HFM (intake air
temperature)Cooling fan
module
DSI 6 A/T (ATF
temperature)Coolant
temperature
sensor
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

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(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
sensorPTC heaterD20DTR ECU
PTC 1 relay
PTC 2 relay
PTC 3 relay
PTC Fuse 3 (40A)PTC Fuse 2 (40A)PTC Fuse 1(40A)
Relay box in engine compartment

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D. PTC operation process
The PTC operating condition (ON) is controlled in two steps.
Basically, the engine ECU controls the relay to supply the power to PTC according to the coolant
temperature sensor and ambient temperature sensor.
1st step (initial operation of PTC)
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Stop (OFF) conditions
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) -
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(14) Immobilizer control
A. Overview
The Immobilizer System provides an additional theft deterrent to the vehicle in which it is installed and
prevents it from being started by unauthorized persons. The transponder integrated in the key and the
engine control unit have the same code. When the ignition key with the integrated transponder is turned
to the ON position, the ECU (Engine Control Unit) checks the crypto code of the key and, if correct,
allows the vehicle to start the engine.
For details, refer to Chapter "Immobilizer".
B. Components
Basic components (ignition key system)
D20DTR ECUImmobilizer antennaInstrument cluster
Immobilizer keyStart motor