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.
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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 241 of 715

05-4
2. CAUTIONS
Do not park the vehicle on flammable materials, such as grass, leaves and carpet.
Do not touch the catalyst or the exhaust gas ignition system when the engine is running.
If a misfire occurs in the combustion chamber or the emission of pollutant exceeds the
specified level, the catalyst can be damaged.
When servicing or replacing components of the exhaust system, makes sure that the
components are positioned at regular intervals from all other parts of the under body.
Be careful not to damage the exhaust system when lifting the vehicle from its side.
All components and body parts of the engine exhaust system should be inspected for crack,
damage, air hole, part loss and incorrect mounting location. Also check for any deformation
which can result in exhaust gas drawn into the vehicle.
Make sure that the exhaust pipe is cooled down sufficiently before working on it because it is
still hot right after the engine is stopped.
Wear protective gloves when removing the exhaust pipe. -
-
-
-
-
-
-
-
Page 242 of 715
05-51729-01
2. LAYOUT
Silencer Assembly
Exhaust manifold assembly
CDPF assembly
1. OVERVIEW
This system purifies the exhaust gas generated by the combustion in the engine to reduce the
pollutants and noise during that arise during combustion.
Exhaust front pipe assembly
For more information, refer to Chapter
"Engine Control". *
Page 245 of 715

06-4
2. INSPECTION
1) Cautions During Driving
The following lists cautions to take during test drive and on the turbocharger vehicle, which must
be considered during the operation.
It's important not to drastically increase the engine rpm starting the engine. It could make
rotation at excessive speed even before the journal bearing is lubricated and when the
turbocharger rotates in poor oil supply condition, it could cause damage of bearing seizure
within few seconds.
If the engine is running radically after replacing the engine oil or oil filter brings poor oil supply
condition. To avoid this, it's necessary to start off after idling the engine for about 1 minute
allowing oil to circulate to the turbocharger after the replacement.
When the engine is stopped abruptly after driving at high speed, the turbocharger continues to
rotate in condition where the oil pressure is at '0'. In such condition, an oil film between the
journal bearing and the housing shaft journal section gets broken and this causes abrasion of
the journal bearing due to the rapid contact. The repeat of such condition significantly reduces
life of the turbocharger.
Therefore, the engine should be stopped possibly in the idle condition. 1.
2.
3.
After string for long period of time during winter season or in the low temperature condition
where the fluidity of engine oil declines, the engine, before being started, should be cranked
to circulate oil and must drive after checking the oil pressure is in normal condition by idling
the engine for few minutes.
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06-51914-01
2) Inspection of Turbocharger
When problem occurs with the turbocharger, it could cause engine power decline, excessive
discharge of exhaust gas, outbreak of abnormal noise and excessive consumption of oil.
On-board Inspection 1.
Check the bolts and nuts foe looseness or missing
Check the intake and exhaust manifold for looseness or damage
Check the oil supply pipe and drain pipe for damages
Check the housing for crack and deterioration -
-
-
-
Inspection of turbine 2.
Remove the exhaust pipe at the opening of the turbine and check, with a lamp, the existence of
interference of housing and wheel, oil leakage and contamination (at blade edge) of foreign
materials.
Interference: In case where the oil leak sign exists, even the small traces of interferences on
the turbine wheel mean, most of times, that abrasion has occurred on the journal bearing.
Must inspect after overhauling the turbocharger.
Oil Leakage: Followings are the reasons for oil leakage condition -
-
Problems in engine: In case where the oil is smeared on inner wall section of the exhaust
gas opening.
Problems in turbocharger: In case where the oil is smeared on only at the exhaust gas
outlet section. *
*
Idling for long period of time can cause oil leakage to the turbine side due to low pressure of
exhaust gas and the rotation speed of turbine wheel. Please note this is not a turbocharger
problem.
Oil Drain Pipe Defect
In case where oil flow from the turbocharger sensor housing to the crank case is not smooth
would become the reason for leakage as oil builds up within the center housing. Also, oil
thickens (sludge) at high temperature and becomes the indirect reason of wheel hub section.
In such case, clogging and damage of the oil drain pipe and the pressure of blow-by gas
within the crank case must be inspected.
Damages due to Foreign Materials.
When the foreign materials get into the system, it could induce inner damage as rotating
balance of the turbocharger gets out of alignment. -
-
-
Page 247 of 715

06-6
3) Inspection of Turbine
Thoroughly check the followings.
Must absolutely not operate the turbocharger with the compressor outlet and inlet opened as it
could damage the turbocharger or be hazardous during inspection.
Interference: In case where is trace of interference or smallest damage on the compressor
wheel means, most of times, that abrasion has occurred on the journal bearing. Must inspect
after the overhaul.
Oil Leakage: The reason for oil leakage at the compressor section is the air cleaner, clogged
by substances such as dust, causes the compressor inlet negative pressure. -
-
Rotating in high speed at no-load for extended period of time can cause oil leakage to the
compressor section as oil pressure within the center housing gets higher than pressure
within the compressor housing.
Overuse of engine break (especially in low gear) in down hill makes significantly low
exhaust gas energy compared to the time where great amount of air is required during
idling conditions of the engine. Therefore, amount of air in the compressor inlet increases
but the turbocharge pressure is not high, which makes negative a.
b.
No problem will occur with the turbocharger if above conditions are found in early stage but oil
leaked over long period of time will solidify at each section causing to breakout secondary
defects.
Damages by foreign materials: In case where the compressor wheel is damaged by foreign
materials requires having an overhaul. At this time, it's necessary to check whether the foreign
materials have contaminated intake/exhaust manifold or inside of engine.
Page 250 of 715
06-91914-01
Turbine Side: Inflow of foreign materials from engine
Compressor Side: such as air filter, muffler and nut 3.