EGR Control Solenoid: Description and Operation

Electric EGR Transducer (EET):

DESCRIPTION

The Electric EGR Transducer (EET) is a back pressure transducer combined with an electric vacuum solenoid. The vacuum solenoid receives its electrical signal from the engine controller. Using this signal, the solenoid regulates the amount of vacuum allowed to flow through the solenoid and on to the transducer. The back pressure transducer measures the exhaust gas back pressure in the exhaust system and uses that reading to vary the strength of the vacuum signal applied to the EGR valve, thereby providing the proper amount of EGR flow for all operating conditions.



SOLENOID OPERATION

Engine controller controls vacuum to transducer by providing solenoid ground. When solenoid is energized no vacuum reaches transducer. Solenoid de-energized vacuum allowed to reach transducer.
Solenoid always energized (no vacuum to transducer):

^During engine warm-up.
^When the engine is at idle.
^During Wide Open Throttle (WOT).
^During rapid acceleration/deceleration.

NOTE: If wiring is disconnected from solenoid EGR valve will operate at all times, affecting engine idle and performance.


BACK PRESSURE TRANSDUCER OPERATION

Transducer is a variable vacuum bleed valve controlled by exhaust system backpressure.

Transducer is supplied vacuum through solenoid. When exhaust vacuum is great enough bleed valve closes completely. When backpressure is present but not great enough to close bleed valve completely, and solenoid is de-energized, varying vacuum is applied to EGR valve providing the correct amount of EGR to the engine for differing operating conditions.