engine SSANGYONG NEW REXTON 2012 Service Manual

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LoadEngine 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: 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.
Swirl valve
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 EGR
To reduce Nox, it is essential to increase EGR ratio. However, if EGR ratio is too high, the PM also
could be very higher. And, the exhaust gas should be evenly mixed with newly aspired air. Otherwise,
PM and CO are dramatically increased in highly concentrated exhaust gas range and EGR ratio
could not be increased beyond a certain limit. If the swirl valve operates in this moment, the limit of
EGR ratio will be higher. -
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F. 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.

(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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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.

(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

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
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LO
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HI
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ONLO
Refrigerant pressure <
18 bar
ON
HI
pressure
HI
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HI
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OFF (cut)
A/C compressor OFF conditions
Approx. 4 seconds after starting the engine
Engine rpm: below 650 rpm or over 4500 rpm
When abrupt acceleration
Refrigerant pressure:
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The output voltage from refrigerant pressure sensor is 1.7 V to 3.5 V when the refrigerant pressure is 10
Output voltage according to refrigerant pressure
Cooling fan controls according to ATF
ATF temperature Fan condition Remark
High speed -

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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