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1. SYSTEM DESCRIPTION
1) 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 D20DTF 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 decreased.
Benefits of E-EGR valve
Improved accuracy and response through electric control
Feedback function (Potentiometer)
Preventing chattering of EGR valve and improved durability
Self-cleaning function -
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1793-01
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.
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.
E-EGR valve
Receives the electric signal from the ECU to
control the valve.
EGR cooler
EGR bypass
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1793-01
2) Input/Output Devices
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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2. CAUTIONS
Standard pattern of soot accumulation
(1) Abnormal Soot Accumulation(2) Normal Soot Combustion
Cautions to protect the catalyst filter
Use the designated fuel only.
Observe the recommended service intervals of engine oil.
Check the engine oil level frequently and add if necessary.
Do not idle the vehicle unnecessarily.
Do not turn off the engine while the vehicle is running.
Do not shift the gear selector lever to neutral when going downhill.
Do not use improper engine oil or fuel additives.
Do not drive for a long time when the warning lamp is illuminated.
Make sure no flammable material, such as dry grass or tissue paper, contacts with the catalyst filter
while the vehicle is parked.
For the vehicles used in urban traffic, driving on the expressways for more than 1 hour at least once
per week is needed so that the PM inside CDPF isn't collected to one side only. -
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1114-00
(3) Warning Lamp Related to CDPF
CDPF regeneration process (warning lamp NOT illuminated)
Overload of CDPF (warning lamp blinking)
The CDPF system enters the regeneration mode
when the driving distance becomes approx. 600
to 1,200 km (may differ by the driving condition
and driving style). Then, the engine ECU
performs the CDPF regeneration operation.
However, the driver is not informed with this
operation by any engine warning lamp or vehicle
signal, so he/she may not detect this operation.
The control logic at the post-injection dur-ing the
regeneration process is to increase the fuel
injection volume and control the intake air volume
(by the throttle body) in order to increase the
temperature of the exhaust gas. The driver may
not feel any particular difference from the vehicle.
If the CDPF cannot reach the regeneration
temperature due to low speed driving or other
reason during the regeneration process, the
soot is continuously accumulated in the
CDPF. When this condition continues and
the CDPF is overloaded with soot, the engine
warning lamp blinks to inform this situation to
the driver.
In order to solve this problem, drive the
vehicle at a speed of approx. 80 km/h for 15
to 20 minutes to perform the CDPF
regeneration process.
If the engine warning lamp on the instrument
cluster blinks, the CDPF is overloaded. In this
case, perform the step 2. 1.
2.
3.
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Excessive overload of CDPF (warning lamp illuminated)
If the vehicle is driven at a speed of 5 to 10
km/h for an extended period of time, the soot
accumulated in the CDPF cannot be burned
as the CDPF cannot reach the regeneration
temperature. Then, an excessive amount of
soot can be accumulated in the CDPF.
This case is much worse than the simple over-
load of the CDPF. To inform this to the driver,
the engine warning lamp comes on and the
engine power is decreased to protect the
system.
To solve this problem, blow soot between the
engine and exhaust system several times and
erase the related DTC. Then, check if the
same DTC is regenerated again. If so, check
the DTC related to the differential pressure
sensor. 1.
2.
3.
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Engine ECU (D20DTF)
Post-injectionDifferential pressure sensor
Calculates the amount of PM
collected by reading the pressure
difference between before and
after the CDPF.Electric throttle body
Regulates the rate of air
intake.
CDPF
(DOC + DPF)Front temperature
sensor
Protects the
turbocharger.Rear temperature
sensor
Measures the
temperature of fuel
combustion.
2. COMPONENT
Oxygen
sensor
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A DPS (Differential Pressure Sensor) measures the pressure difference between before and after the
CDPF and detects whether the soot is collected in the CDPF or not. If PM is collected in the CDPF (In
this case the pressure difference between before and after the CDPF exceeds the specified value.
Normally, the system sends the signal when the driving distance becomes approx. 600 to 1,200 km), the
temperature of exhaust gas is increased and the post-injection is started for regeneration. The amount of
fuel post-injection is controlled by the exhaust gas temperature measured by the rear temperature
increase the regeneration temperature. Otherwise, the fuel injection amount is decreased or the fuel is
not injected.
When the engine is running with low load, the intake air amount is also controlled as well as fuel injection
amount. This function is used to increaser the combustion temperature by increasing the amount of fuel
post-injection with the lowest air amount within the specified control logic.
4. POST-INJECTION AND AIR MASS CONTROL