SsangYong Stavic / SsangYong Rodius (2005 year). Manual - part 109

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EXHAUST SYSTEM

DI ENG SM - 2004.9

EGR System Diagram

EGR Valve

EGR valve recirculates some of exhaust gases to intake system to reduce toxic NOx from engine according to ECU
signals.

• EGR valve opening point : -270 mmHg

EGR Modulator

According to ECU signals, the vacuum modulator drives EGR valve by controlling vacuum pressure that is generated by
vacuum pump with PWM type controls.

Intercooler

Exhaust

manifold

Intake

manifold

EGR

valve

Regulated

vacuum

pressure

Modulator

Vacuum

pump

Duty

control

Feedback EGR

(Air Mass)

ECU

Improved target EGR

Air intake signal

(for EGR feed-

back control)

Turbo charger

Pedal

signal

RPM

signal

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DI ENG SM - 2004.9

Operation Principle of Vacuum Modulator

According to ECU signals, the solenoid valve controls the vacuum pressure that is generated by vacuum pump (-900 

±

20 mbar) with PWM type control and drives the mechanical EGR valve and turbo charger.

Vacuum pump

Output vacuum

ATM

Plunger

Connector

Diaphragm

Vacuum control

Seat assembly
Spring

Atmospheric pressure

Plunger

Air flow

During duty increase (B)

During duty reduction (C)

Vacuum is controlled according to relationship between chamber pressure (I) in rolling nipple cover and magnetic
force (II) in plunger.

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EXHAUST SYSTEM

DI ENG SM - 2004.9

Operating principle: Balance between original vacuum pressure and magnetic force (see above figure)

• Normal state (Fig. A): Original vacuum and seat section, 3 stoppers keep sealing

• Duty up state (Fig. B): Original vacuum pressure is connected to inside of diaphragm chamber

• Duty down state (Fig. C): Increased diaphragm chamber pressure is connected to atmosphere to compensate the

pressure.

 Operating principles when duty is applied from 0 to 50 %

Vacuum consumption: Compared to 50 % of duty, ON/OFF periods are most unstable and vacuum
consumption is most high.

Output Characteristics

Floating plunger

DUTY 50%

Output C/V

Stroke

(mm)

Max. Distance 

 1mm

Flowing

volume

Output vacuum (-mmHg)

Up

Down

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EXHAUST SYSTEM

DI ENG SM - 2004.9

Operating Conditions

• Engine is running

• Engine RPM is within a specified range. (EGR OFF under high RPM range)

• Engine torque is within a specified range. (EGR OFF under high torque range)

• Vehicle speed is within a specified range. (EGR OFF under high speed range)

• Atmospheric pressure is within a specified range. (EGR OFF under high altitude and low atmospheric pressure)

• Coolant temperature is within a specified range. (EGR OFF under high or low temperature)

• EGR OFF under extended period of idling.

Control Logic

• Main map: EGR volume is controlled based on intake air volume

• Auxiliary map

- Coolant temperature (Coolant temperature sensor)

- Engine rpm (Crankshaft position sensor)

- Engine load (TPS): Detection of sharp acceleration

- Intake air temperature (HFM): Decreases when over 60°C

- Atmospheric pressure (Barometric sensor): Compensation of altitude

• Compensation value of auxiliary map will be increased/decreased based on main map then ECU calculates EGR

volume finally to regulate the vacuum duty that applies to the vacuum modulator to control EGR valve openings.

Shut-off Conditions

• Engine rpm: over 2,950 rpm

• Vehicle speed: over 105 km/h

• Coolant temperature: over 100°C or below 10°C

• Idle period: over 50 seconds