SsangYong Stavic / SsangYong Rodius (2005 year). Service manual — part 109
DI04-29
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AFFECTED VIN
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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EXHAUST SYSTEM
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.
DI04-31
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AFFECTED VIN
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
DI04-32
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EFFECTIVE DATE
AFFECTED VIN
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
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