Page 38 of 751

02-70000-00
3. CHECK AND INSPECTION
1) Cylinder
(1) Compression pressure test
Specified value ▶
Compression ratio16.5 : 1
Test conditionat normal operating temperature (80˚C)
Compression pressureStandard32 bar
Minimum18 bar
Differential limit between cylindersMaximum 3 bar
The compression pressure test is to check the conditions of internal components (piston, piston ring,
intake and exhaust vale, cylinder head gasket). This test provides current engine operating status.
Before cranking the engine, make sure that the test wiring, tools and persons are keeping away
from moving components of engine (e.g., belt and cooling fan).
Park the vehicle on the level ground and apply the parking brake.
Do not allow anybody to be in front of the vehicle. -
-
-
Measurement ▶
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47004f005f005700b6006a00500055>
Disconnect the fuel rail pressure sensor connector to cut off the fuel injection.
Remove the air cleaner duct and glow plugs. -
-
-
Place the diagram sheet to compression
pressure tester and install it into the plug hole. 1.
Page 190 of 751
14-6
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.
Page 193 of 751
14-92412-02
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". *
Page 194 of 751

14-10
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.
Page 195 of 751

14-112412-02
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 measured by the rear temperature
<009a008c0095009a00960099005500470070008d0047009b008f008c0047009b008c00940097008c00990088009b009c0099008c00470090009a00470093008c009a009a0047009b008f008800950047005d005700570b4500530047009b008f008c004700
8800940096009c0095009b00470096008d004700970096009a>t-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.
Page 196 of 751

14-12
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.
Boos
t
pressure
/
temperature
Injector (C31)
Controls the post injection.
Electric throttle body
Controls the intake air mass.
HFM sensor
Wide band
oxygen senso
r
Page 197 of 751
14-132412-02
Collecting PM
→ Regeneration
The engine ECU detects the
amount of PM collected by the
information from the
temperature sensors and
differential pressure sensor.
When the soot is accumulated,
the engine ECU performs post-
injection to increase the
exhaust gas temperature and
burns the collected PM at
approx. 600°C.Oxidation (DOC)
When the exhaust gas enters
into the CDPF assembly, its
CO, HC and PM are reduced
by the redox reaction of the
DOC. The remaining PM is
filtered and collected in CDPF,
and the temperature of the
exhaust gas is increased to
between 450 and 500°C.
5. OPERATING PROCESS
[Configuration and principle of operation]
The exhaust gas
passed through the
exhaust manifold
enters into the CDPF
assembly (at approx
250℃).
Page 200 of 751
14-16
3) PM Regeneration of DPF
The differential pressure sensor installed in the DPF measures the pressure values of inlet and outlet of
CDPF. And the amount of the PM collected in the filter is calculated based on the exhaust temperature,
intake air mass flow, booster pressure, etc.
The regeneration is started when the amount of the collected PM is 28 g or more.
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940097008c00990088009b009c0099008c00470096008d0047>CDPF to 600℃.
When the amount of the collected PM is not enough: The DPF works as a filter. 1.
When enough amount of PM is collected: The ECU commands post-injection and increase the exhaust
gas temperature to start regeneration. 2.