SsangYong Korando III (2010 year). Service manual — part 370

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c. Input/Output of E-EGR system

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d. Bypass control for EGR cooler

1. Cooler temperature

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

2. 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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f. Features

As EGR ratio goes up, smoke volume will be

higher. But, this lowers the combustion chamber

temperature and accordingly the concentration of

NOx is decreased. The point with highest NOx is

immediately after TDC.

As EGR temperature goes up, the

concentration of NOx will be higher. Thus, it is

necessary to cool down the exhaust gas.

However, during engine cooled, it may cause

large amount of PM. To prevent this, the

exhaust gas is bypassed the EGR cooler.

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Accelerator

pedal

E-VGT

actuator

Coolant

temperature

Front EGT

sensor

T-MAP sensor

Crankshaft pos,

sensor

HFM sensor

(intake air temp)

ECU

(D20DTF)

(6) E-VGT control

a. Overview

E-VGT (Electric-Variable Geometry Turbine) turbocharger system in D20DTF engine uses the venturi

effect that controls the flow rate of exhaust gas by adjusting the passage in turbine housing. The newly

adopted DC motor actuator (E-actuator) controls the E-VGT system more precisely and faster. To get

the high operating power from turbine, the ECU reduces the exhaust gas passage In low speed range

and increases it in high speed range.

b. Components