Pintle

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Spring
Pintle
Passages
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• Types of EGR
• Single Diaphragm
• Used with or without PCM controls

• When the engine is idling, opening valve should
  stall the engine
• Opens fully with about 8 Hg.
• Used with a thermal vacuum switch and a possible
  vacuum delay valve.
• Single diaphragm may be used in an electronically
  controlled systems
• Basic standard since 1973

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• Types of EGR
• Integral Backpressure
• With or without PCM
• Internal Modulator controls EGR flow based on
  positive or negative exhaust pulses

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• Types of EGR
• External Modulator
• With or without PCM
• External Modulator controls EGR flow based
  exhaust pressure

Vacuum modulation is vital for good driveability
and precise NOx control.
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• Types of EGR
• External sensor
• PCM commands solenoid (VSV)
• Sensor reports EGR valve position to PCM
• May use 2 solenoids (vacuum and vent)

EGR SOLENOID
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• Types of EGR
• Linear Solenoid EGR
• No vacuum control
• PCM PWM
• Improved accuracy
• Faster response (10X)
• Improved diagnostics

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• Types of EGR
• Linear EGR schematic

5 wire 2 for solenoid 3 for sensor
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• Types of EGR
• GM digital
• No vacuum
• 3 solenoids, 3 different exhaust ports.
• Valves may be operated separately or together to
  control EGR.

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• Types of EGR
• GM Digital Schematic

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• Types of EGR
• GM Integrated Electronic

• Combines vacuum and electronic operation
• PCM controlled vacuum regulator is built into the
  top of the EGR valve.
• PWM signals operate regulator solenoid and
  control vacuum.
• Ported vacuum is supplied to the EGR valve
  assembly.
• EGR pintle sensor provides feedback to the PCM to
  verify desired action has occurred.

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• Types of EGR
• GM EGR solenoid details.

• PCM controlled PWM
• PCM regulates the time the EGR is open by
  regulating solenoid on time (more EGR).
• Percentage of solenoid on time is the duty cycle
• 0 equals no EGR 100 equals maximum EGR.
• EGR vacuum switch signals PCM -vacuum present

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High backpressure
Low backpressure

• External Modulator with PCM controlled vacuum
  solenoid
• PCM command opens or closes vacuum solenoid
• Modulator controls EGR flow based on vacuum
  exhaust backpressure
• Vacuum signal varies through throttle opening

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Various EGR controls