SsangYong Rodius (2013 year). Manual - part 89

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Load

Engine speed

Swirl 

valve

Amount of 

swirl

Remarks

Low speed,

Low load

below 3,000 rpm

Closed

Heavy

Increased EGR ratio, better air-fuel 
mixture (reduce exhaust gas))

High speed,

High load

over 3,000 rpm

Open

Light

Increase 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

E. 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.

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F. Relationship between swirl and fuel injection pressur

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.

15-28

Electric throttle 

body

Accelerator 

pedal 

module

D20DTR 

ECU

(9) EGR control

A. Overview

The EGR (Electric-Exhaust Gas Recirculation) valve reduces the NOx emission level by recirculating 

some of the exhaust gas to the intake system.

To meet Euro-V regulation, the capacity and response rate of E-EGR valve in D20DTR engine have 

been greatly improved. The EGR cooler with high capacity reduces the Nox, and the bypass valve 

reduces the CO and HC due to EGR gas before warming up.

Also, the engine ECU adjusts the E-EGR opening by using the air mass signal through HFM sensor. If 

the exhaust gas gets into the intake manifold when the EGR valve is open, the amount of fresh air 

through HFM sensor should be decresed.

B. Components

E-EGR cooler

Coolant 

temperature 

sensor

Oxygen sensor

HFM (intake 

air 

temperature)

Crankshaft 

position 

sensor

E-EGR valve

T-MAP 

sensor

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C. Input/Output of E-EGR system

15-30

D. Bypass control for EGR cooler

Cooler temperature

▶

When the coolant temperature is below 70℃, the exhaust gas is bypassed the EGR cooler.

Exhaust gas temperature

▶

When the exhaust gas temperature is below 300℃, the exhaust gas is bypassed the EGR cooler

Otherwise, PM could be increased due to too low exhaust gas temperature.

E.  Control elements for EGR system

Accelerator pedal (engine load) - Indicates the driver's intention and engine load. If the load goes 

up, the EGR ratio is decreased.

T-MAP (boost pressure map stored in ECU) - Compensates the difference in boost pressure by 

adjusting EGR ratio.

Engine rpm - Used as the signal for determining EGR operating range.

Coolant temperature - When the coolant temperature is low, NOx is decreased but PM could be 

increased. So, to reduce PM, decrease EGR ratio when the coolant temperature is low.

Intake air mass and temperature - HFM sensor measures the intake air mass to calculate the 

actual EGR volume. If the air mass is larger than programmed value in map, EGR ratio will be 

higher.

EGR position sensor - Detects the actual opening angle of EGR valve and performs feedback 

function according to PWM control by ECU.

Wide band oxygen sensor - Detects the oxygen volume in exhaust gas to check if the EGR ratio is 

proper.

Electronic throttle body - Keeps EGR ratio to optimized level by controlling the throttle body in EGR 

operating range (decreasing pressure in intake manifold).

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