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14-4
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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14-52412-02
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.
Overload of CDPF (warning lamp blinking)
(3) Warning Lamp Related to CDPF
CDPF regeneration process (warning lamp NOT illuminated) ▶
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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14-8
Differential pressure
sensor
Calculates the amount of
PM collected by reading
the pressure difference
between before and after
the CDPF.Engine ECU
DCM 3.7
Post-injectionThrottle
valve
Regulates the rate of air
intake.
CDPF
DOC+DPFFront temperature sensor
Protects the
turbocharger.
Rear temperature sensor
Measures the
temperature of fuel
combustion.
2. COMPONENT
For details, refer to section "Engine Control". *
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14-92412-02
3. INPUT/OUTPUT DEVICES
Front temperature sensor: This sensor is installed at the inlet of DOC and detects whether
the DOC can burn (oxidize) the post-injected fuel or not.
Rear temperature sensor: This sensor is installed at the inlet of DPF and monitors that the
temperature of the exhaust gas is kept at 600℃. 1.
2.
<0070008d0047009b008f008c0047009b008c00940097008c00990088009b009c0099008c0047008c009f008a008c008c008b009a0047005d005700570b4500530047009b008f008c004700930090008d008c00470096008d0047006a006b0077006d004700
8a0088009500470089008c00470099008c008b009c008a008c>d. So the amount of fuel
post-injection is decreased.
<0070008d0047009b008f008c0047009b008c00940097008c00990088009b009c0099008c0047008b009900960097009a0047009c0095008b008c00990047005d005700570b4500530047009b008f008c004700990088009b008c00470096008d0047009900
8c008e008c0095008c00990088009b0090009600950047008a>an be decreased. So the
amount of fuel post-injection is increased. -
-
Differential pressure sensor: This sensor checks the amount of PM collected by calculating the
pressure difference between before and after the CDPF.
Electric throttle valve: This valve reduces the intake air flow to raise the temperature of the
exhaust gas when the CDPF is operating during idling. 3.
4.
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14-10
4. POST-INJECTION AND AIR MASS CONTROL
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
<009b008c00940097008c00990088009b009c0099008c00470094008c0088009a009c0099008c008b0047008900a00047009b008f008c00470099008c008800990047009b008c00940097008c00990088009b009c0099008c0047009a008c0095009a009600
99005500470070008d0047009b008f008c0047009b008c0094>perature is less than 600℃, the
amount of post-injection is increased to 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.
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14-112412-02
Front temperature sensor
Measures the temperature of
exhaust gas.
This sensor is located at the rear
side of exhaust manifold and
monitors the temperature of
combusted gas to prevent the
exhaust system from overheating.
When the temperature gets
higher, this sensor cuts off the
fuel delivery and controls the EGR
to lower the temperature.Rear temperature sensor
Measure the outlet
temperature of DOC.
This sensor is located at
the rear side of DOC and
monitors the overheating of
CDPF and post injection
volume.
Engine ECU (D20DTR)
Differential pressure sensor
Measures the difference between
inlet and outlet pressures of
CDPF.
If the difference is higher than the
specified value when collecting
the PM, this makes the post
injection for forced recycling of
PM.
T-MAP sensorIntake air
mass
Measures
the
excessive
amount of
PM.
Boost
pressure/
temperature
Injector (C31)
Controls the post injection.
Electric throttle body
Controls the intake air
mass.
HFM sensor
Wide band
oxygen sensor
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14-132412-02
1) Oxidation of DOC
The DOC oxidizes HC and CO of the exhaust gas in the two-way catalytic converter at 180℃ or
<009400960099008c0053004700880095008b00470097008c0099008d009600990094009a00470089008c009a009b00470088009b0047009b008f008c0047009b008c00940097008c00990088009b009c0099008c00470089008c009b009e008c008c009500
47005b00570057004700880095008b0047005c005700570b45>. The front EGT sensor
detects whether the DOC can burn (oxidize) the post-injected fuel or not, and sends the signal to
<009b008f008c0047006c006a007c0047009b009600470094008800900095009b0088009000950047009b008f008c0047006b0076006a004700960097008c00990088009b00900095008e0047009b008c00940097008c00990088009b009c0099008c004700
89008c009b009e008c008c00950047005a0057005700470088>nd 500℃. The DOC reduces
CO and HC of the exhaust gas by redox reaction and also reduces small amount of PM.
<0058005500470076009f00a0008e008c009500470088008b008f008c0099008c009a0047009b00960047009b008f008c0047008a0088009b0088009300a0009a009b004700940088009b008c0099009000880093009a006100470073008c009a009a004700
9b008f0088009500470058005f00570b45>
2. CO and HC are oxidized by the catalyst materials: More than 180℃
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14-14
2) Collecting PM of DPF
There is a filter installed in the DPF and the PM filtered by this filter is burned (regeneration) when
the temperature of exhaust gas is increased due to post-injection. The filter has a honeycomb-
like structure to capture the particulate matter and the inlet and outlet of each channel are closed
alternatively. Once the exhaust gas enters to the inlet of a channel, it is released from the outlet of
the adjacent channel through the porous wall because of the closed outlet of the first channel,
and the PM is collected in the first channel.
[Collecting PM of CDPF]
Normally, when the driving distance becomes approx. 600 to 1,200 km, enough amount of
soot to be burned is filtered and accumulated in the CDPF. The ECU increases the amount of
fuel post-injection to increase the temperature of the exhaust gas up to 600°C, so that the
soot is burned. The soot is burned for 15 to 20 minutes (may differ by conditions).