Page 233 of 715
04-51719-00
3) Troubleshooting Sequence
The basic checks for intake system are as follows:
Basic Checks for Intake System ▶
Make sure to replace or clean the air cleaner
element periodically. Otherwise, engine will be
derated or work abnormally because of low
intake air volume.
Unlike the fuel system, which is a closed
circuit, the intake system is an open circuit
system. Therefore any malfunction may occur
due to dust and dirt.
Most of the connections consist of hoses so
the system cannot withstand high temperature
and pressure. Also it can be deformed or
loosened easily because it is a clamp
mounting system. Thus, when checking the
engine, basic inspections, such as tightened
status check and visual inspection for hose,
etc., should be carried out in advance.
Other Checks for Intake System ▶
If the intake system is free of any faults,
check for EGR and PCV oil separator.
Page 238 of 715

04-10
1) Types of swirl
Swirl: One cylinder has two intake air ports, one is set horizontally
and the other one is set vertically. Swirl is the horizontal air flows in
cylinder due to the horizontal intake air ports.
Tumble: Tumble is the vertical air flows in cylinder due to the
vertical intake air port
Squish: Squish is the air flows due to the piston head. Normally,
this is appears at the final process of compression. In CRDi
engine, the piston head creates the bowl type squish.
2) Swirl control
In DI type diesel engine, the liquefied fuel is injected into the cylinder directly. If the fuel is evenly
distributed in short period, the combustion efficiency could be improved. To get this, there should
be good air flow in cylinder. In general, there are two intake ports, swirl port and tangential port, in
each cylinder. The swirl port generates the horizontal flow and the tangential port generates the
longitudinal flow. In low/mid load range, the tabgential port is closed to increase the horizontal
flow. Fast flow decreases the PM during combustion and increases the EGR ratio by better
combustion efficiency.
Page 239 of 715

04-111719-00
LoadEngine
speedSwirl valve Amount of
swirlRemarks
Low speed,
Low loadbelow
3,000 rpmClosed HeavyIncreased EGR ratio, better air-fuel
mixture (reduce exhaust gas)
High speed,
High loadover 3,000
rpmOpen LightIncrease charge efficiency, higher
engine power
The variable swirl valve actuator operates
when turning the ignition switch ON/OFF
position to open/close the swirl valve. In this
period, the soot will be removed and the
learning for swirl valve position is performed.
Swirl: This is the twisted (radial) air flow along the cylinder wall during the intake stroke. This
stabilizes the combustion even in lean air-fuel mixture condition.
Swirl valve
3) Features
Swirl and air intake efficiency
To generate the swirl, the intake port should be serpentine design. This makes the resistance
in air flow. The resistance in air flow in engine high speed decreases the intake efficiency.
Eventually, the engine power is also decreased, Thus, the swirl operation is deactivated in high
speed range to increase the intake efficiency.
Relationship between swirl and EGR
To reduce Nox, it is essential to increase EGR ratio. However, if EGR ratio is too high, the PM
also could be very higher. And, the exhaust gas should be evenly mixed with newly aspired air.
Otherwise, PM and CO are dramatically increased in highly concentrated exhaust gas range
and EGR ratio could not be increased beyond a certain limit. If the swirl valve operates in this
moment, the limit of EGR ratio will be higher. -
-
4) Relationship Between Swirl and Fuel Injection Pressure
The injector for DI engine uses the multi hole design. For this vehicle, there are 8 holes in injector.
If the swirl is too strong, the injection angles might be overlapped and may cause the increased
PM and insufficient engine power. Also, if the injection pressure is too high during strong swirl, the
injection angles might be overlapped. Therefore, the system may decreases the fuel injection
pressure when the swirl is too strong.
Page 259 of 715
06-18
Maximizes the intake air charging efficiency (Approx. 15%) -Optimizes the exhaust gas flow rate by controlling the vanes inside the turbine housing with
the EActuator. 1.
(2) E-VGT Actuator (Electric-Actuator)
Target temperature and airflow control -Enhanced emmission control: By temperature control with CDPF system 1.
(1) Performance (for EURO V)
Has a faster response time than the conventional vacuum actuator. 2.
Improved low speed torque, high speed power and fuel economy.
Improved acceleration performance with rapid response time of vane. -
-
1) Features
Features
Benefits
Folding and unfolding of the vane
is controlled electrically
Easy to get low speed air volume
Rapid response time
Electric control -
-
-
-
Improved low speed torque and
power
Reduced exhaust gas
Improved fuel consumption
Improved acceleration
performance -
-
-
-
Page 287 of 715
10-4
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
Engine ECU (D20DTR)Glow indicator
Glow plug control unit
(GCU)
Page 313 of 715
14-32412-02
1. 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. -
-
-
-
-
-
-
-
-
-
Page 314 of 715

14-4
Overload of CDPF
(warning lamp blinking)Excessive overload of CDPF
(warning lamp illuminated)
(3) Warning Lamp Related to CDPF
CDPF regeneration process (warning lamp NOT illuminated) ▶
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.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.
OFF
BlinkingIlluminating
Page 317 of 715

14-72412-02
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.