engine coolant SSANGYONG NEW REXTON 2012 Owner's Manual

1. OVERVIEW
The pre-heating system for D20DTR engine has the glow plug to the cylinder head (combustion
chamber), and improves the cold start performance and reduces the emission level.
The pre-heating resistor (air heater) is used to heat the intake air.
This enables the diesel fuel to be ignited in low temperature condition.
The ECU receives the information such as, engine rpm, coolant temperature, engine torque, etc.,
through CAN communication during pre-heating process; and the pre-heating control unit controls the
pre-heating, heating during cranking and post-heating by the PWM control.
Glow plug
Glow indicatorEngine ECU (D20DTR)
Glow plug control unit
(GCU)

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Voltage pattern in actual stepGCU PWM control
4) Operation
Glow plug is installed in the cylinder head. It enhances the cold starting performance and reduces the
exhaust gas during cold starting.
ECU receives the data (engine rpm, coolant temperature, vehicle speed) through CAN lines. Based on the
data, GCU controls the pre-glow, cranking and post-glow. It also checks the glow plugs, and sends the
result to ECU.
Duty control area:
Between 5 and 100%
Frequency: 20 Hz
1.
2.
3.
(1) Temperature/Current Properties of GCU
FETs (similar to transistor) for each cylinder are integrated in GCU. During the pre-glow period, battery
voltage is supplied to the glow plugs directly to heat them rapidly.
After getting the desired temperature by pre-glowing, the temperature is controlled by duty ratio. 1.
2.
3.
Frequency:
20~33Hz
PWM control duty
ratio
- 1st step: 100%
- 2nd step: 35%
- 3rd step: 23%
This describes the voltage supplying types to glow plugs. This shows the supplying voltage and
time by GCU in each step. The 3rd
step is the period to keep the
temperature.
(2) Operation Type of GCU

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E-EGR valve
Receives the electric signal from the ECU to
control the valve.
E-EGR cooler and bypass valve
The cooler lowers the high temperature of the
exhaust gas and the bypass valve directly
supplies the exhaust gas to the intake duct
without passing through the EGR cooler to
reduce the emission of exhaust gas before
warming up the engine.
2) Location and Components
HFM sensor
Used as a main map value to control the EGR.
The coolant temperature, engine rpm, engine
load, intake air temperature (HFM: decreased at
(atmospheric pressure sensor: altitude
compensation) are used as auxiliary map values.
EGR pipe
Transports the exhaust gas from the EGR cooler
and EGR bypass valve to the intake duct.
See the section "Engine control" for E-EGR
valve control logic.
EGR cooler
EGR bypass
For details, see the section "Engine control". *

3) Control Logic
The EGR system controls the EGR amount based on the map values shown below:
Main map value: Intake air volume
Auxiliary map value:
Compensation by the coolant temperature
Compensation by the atmospheric pressure: Altitude compensation
Compensation by the boost pressure deviation (the difference between the requested value and the
measured value of boost pressure)
Compensation by the engine load: During sudden acceleration
Compensation by the intake air temperature -
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The engine ECU calculates the EGR amount by adding main map value (intake air volume) and auxiliary
map value and directly drives the solenoid valve in the E-EGR to regulate the opening extent of the EGR
valve and sends the feedback to the potentiometer.
(1) Operating conditions
Atmospheric pressure: 0.92 bar or more
When there is no fault code related to EGR -
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(2) Shut off conditions
Abrupt acceleration: with engine speed of 2600 rpm or more
When the engine is idling for more than 1 minute
Vehicle speed: 100 km/h or more
Engine torque: 380 Nm or more -
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1. ENGINE DATA LIST
Data Unit Value
Coolant temperature
Intake air temperature
temperature or engine mode)
Idle speed rpm
Engine load % 18~25%
Mass air flow kg/h 16 to 25 kg/h
Throttle position angle
Engine torque Nm varies by engine conditions
Injection time ms 3 to 5ms
Battery voltage V 13.5 V to 14.1 V
Accelerator pedal position 1 V 0.4. to 4.8V
Accelerator pedal position 2 V 0.2 to 2.4 V
Throttle position 1 V 0.3 to 4.6 V
Throttle position 2 V 0.3 to 4.6 V
Oxygen sensor mV 0 to 5 V
A/C compressor switch 1=ON / 0=OFF -
Full load 1=ON / 0=OFF -
Gear selection (A/T) 1=ON / 0=OFF -
Knocking control 1=ON / 0=OFF -
Brake switch 1=ON / 0=OFF -
Cruise control 1=ON / 0=OFF -

b. Pilot Injection
Injection before main injection. Consists of 1st and 2nd pilot injection, and Pre-injection
Inject a small amount of fuel before main injection to make the combustion smooth. Also, called as
preliminary injection or ignition injection. This helps to reduce Nox, engine noise and vibration, and to
stabilize the idling.
The injected fuel volume is changed and stopped according to the coolant temperature and intake air
volume.
Pilot injection is much earlier than main injection due to higher engine rpm
Too small injection volume (insufficient injection pressure, insufficient fuel injection volume in main
injection, engine braking)
System failure (fuel system, engine control system) -
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Pilot injection
Main injection
Combustion pressure with pilot injection
Combustion pressure without pilot injection 1.
2.
1a.
2b. Stop conditions
Combustion pressure characteristic curve for pilot injection

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c. Main Injection
The power of the vehicle is determined by the main fuel injection volume.
Main injection calculates the fuel volume based on pilot injection. The calculation uses the value for
accelerator pedal position, engine rpm, coolant temperature, intake air temperature, boost pressure,
boost temperature and atmospheric pressure etc.
d. Post Injection
Injection after main injection. Consists of After injection, Post 1, Post 2 injection.
Post injection reduces PM and smoke from exhaust gas. No actual output is generated during these
injections, instead, fuel is injected to the unburned gas after main injection to enable fuel activation. The
PM amount in the emission and smoke can be reduced through these processes.
Only up to 5 types of injections can be performed within 1 cycle. If these 7 injections are all performed,
fuel economy and emission performance becomes poor.

(3) Fuel Pressure Control
Fuel pressure is controlled by IMV opening according to the calculated value by ECU.
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. -
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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.
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. -
-Fuel Pressure

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Pilot injection timing control
The pilot injection timing is determined as a function of the engine speed and of the total flow.
The elements are:
A first correction is made according to the air and coolant temperatures. This correction allows the
pilot injection timing to be adapted to the operating temperature of the engine.
A second correction is made according to the atmospheric pressure. This correction is used to adapt
the pilot injection timing as a function of the atmospheric pressure and therefore the altitude. -
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(4) Injection Timing Control
Injection timing is determined by the conditions below.
Coolant temperature
Hot engine - Retarded to reduce Nox
Cold engine - Advanced to optimize the combustion 1.
Atmospheric pressure
Advanced according to the altitude 2.
Warming up
Advanced during warming up in cold engine 3.
Rail pressure
Retarded to prevent knocking when the rail pressure is high 4.
EEGR ratio
Advanced to decrease the cylinder temperature when EGR ratio increases 5.
Main injection timing control
The pulse necessary for the main injection is determined as a function of the engine speed and of the
injected flow.
The elements are:
A first correction is made according to the air and coolant temperatures.
This correction makes it possible to adapt the timing to the operating temperature of the engine.
When the engine is warm, the timing can be retarded to reduce the combustion temperature and
polluting emissions (NOx). When the engine is cold, the timing advance must be sufficient to allow
the combustion to begin correctly.
A second correction is made according to the atmospheric pressure.
This correction is used to adapt the timing advance as a function of the atmospheric pressure and
therefore the altitude.
A third correction is made according to the coolant temperature and the time which has passed since
starting.
This correction allows the injection timing advance to be increased while the engine is warming up
(initial 30 seconds). The purpose of this correction is to reduce the misfiring and instabilities which are
liable to occur after a cold start. -
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B. Driver Demand
The driver demand is the translation of the pedal position into the fuel demand. It is calculated as a
function of the pedal position and of the engine speed. The driver demand is filtered in order to limit the
hesitations caused by rapid changes of the pedal position. A mapping determines the maximum fuel
which can be injected as a function of the driver demand and the rail pressure. Since the flow is
proportional to the injection time and to the square root of the injection pressure, it is necessary to limit
the flow according to the pressure in order to avoid extending the injection for too long into the engine
cycle. The system compares the driver demand with this limit and chooses the smaller of the 2 values.
The driver demand is then corrected according to the coolant temperature. This correction is added to
the driver demand.