2012 SSANGYONG RODIUS fuel

14-8
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 temperature
<0094008c0088009a009c0099008c008b0047008900a00047009b008f008c00470099008c008800990047009b008c00940097008c00990088009b009c0099008c0047009a008c0095009a00960099005500470070008d0047009b008f008c0047009b008c00
940097008c00990088009b009c0099008c00470090009a0047>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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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.
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.
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.
Engine ECU (D20DTR)
T-MAP sensorIntake air
mass
Measures
the
excessive
amount of
PM.
Injector (C31)
Controls the post injection.
Electric throttle body
Controls the intake air
mass.
HFM sensor
Wide band
oxygen
sensor
Boost
pressure/
temperature

14-112412-02
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.
<0076009f00a0008e008c009500470088008b008f008c0099008c009a0047009b00960047009b008f008c0047008a0088009b0088009300a0009a009b004700940088009b008c0099009000880093009a006100470073008c009a009a0047009b008f008800
9500470058005f00570b45> 1.
<006a0076004700880095008b0047006f006a004700880099008c00470096009f0090008b009000a1008c008b0047008900a00047009b008f008c0047008a0088009b0088009300a0009a009b004700940088009b008c0099009000880093009a0061004700
7400960099008c0047009b008f0088009500470058005f0057>℃ 2.

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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).

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4) Fuel Injection During CDPF Regeneration
The injection method in D20DTR engine has three steps;
Pilot injection, Main injection, Post injection
Post injection ▶
<007b008f008c004700970096009a009b0047009000950091008c008a009b00900096009500470090009a0047009b008f008c0047009000950091008c008a009b0090009600950047009700990096008a008c009a009a00470088008d009b008c0099004700
940088009000950047009000950091008c008a009b00900096>n and consists of ‘After injection”,
“Post 1 injection” and “Post 2 injection”. All of post injections are to reduce the PM and harmful
exhaust gas. The post injection does not make the actual output. The post injection activates the
fuel by injecting the fuel to the incompletely combusted gas after primary combustion. Through
the process, the PM and smoke in the exhaust gas could be reduced. There are totally 7
injections as shown in the figure. However, all of 7 injections are not performed during driving
because it decreases the fuel economy. Totally 5 injections can be performed in one cycle.

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7. CAUTIONS
1) Designated Engine Oil for CDPF (Low Ash Oil)
Need to use the designated engine oil for CDPF 1.
The smoke from the vehicle may generate the particle material in the ambient air. CDPF is
the device to reduce the smoke by collecting and recycling it. To ensure the performance
of CDPF, the designated engine oil should be used.
The smoke including combusted sulfur in fuel cannot be recycled in CDPF. This smoke
generates the ash, resulting in clogging the filter. -
-
Advantages when using the designated engine oil for CDPF 2.
Reduces the amount of ash
Improves the fuel economy and reduces the CO2
Increases the life span of engine oil
Available for all engines (diesel and gasoline) -
-
-
-
Problems when using non-designated engine oil for CDPF 3.
Decreases the life span of engine oil due to accumulated ash in DPF (around 30%)
Decreases the fuel economy due to friction resistance, exhaust gas resistance and
frequent recycling process of DPF -
-
The fuel containing high sulfur may cause the same problems.

14-172412-02
2) Do Not Use the Fuel Containing High Sulfur
Producing white smoke during recycling 1.
The sulfur in exhaust gas is changed to sulfate gas during exhaust process. This sulfate
gas is shown as white smoke. -
Producing odor during recycling 2.
The sulfur after oxidation may produce the odor. -
Accumulation of ash 3.
The sulfur accumulated in DPF cannot be recycled. It reduces the life span of DPF. -
3) White Smoke
The white smoke can be generated when the exhaust gas is recycled in DPF. There are two
reasons as below.
Saturated vapor 1.
Sulfate 2.
The vehicle equipped with CDPF system may generate the white smoke when using the fuel
with high sulfur content (over 100 ppm). This is caused by the sulfur attached and
accumulated in CDPF. However, this is very natural situation, not caused by your vehicle.
How to fix the problem
<0079008c009700930088008a008c0047008a009c00990099008c0095009b0047008d009c008c00930047009e0090009b008f0047008f0090008e008f0047008e00990088008b008c0047008d009c008c009300470088009a0047009a009600960095004700
88009a004700970096009a009a009000890093008c00550047>How­ever, even after
replacing the fuel, the white smoke may be seen due to residual sulfur in CDPF system. -
-

15-6
Fuel Rail Pressure SensorFront EGT Sensor
Differential Pressure SensorCamshaft Position SensorRear EGT Sensor