http://www.oldsgmail.com


Reference Manual


Chapter 10: Emissions Equipment: EFE System


Purpose:

The EFE system is used to provide a source of rapid heat to the engine induction system during cold driveaway. Rapid heating is desireable because it provides quick fuel evaporation and more uniform fuel distribution to aid cold driveability.

Operation:

There are two types of EFE systems: The vacuum servo type and the electrically heated type.

The Vacuum Servo type uses a valve and vacuum actuator which increases the exhaust gas flow under the intake manifold during cold engine operation. The valve is located in the exhaust and is vacuum operated. It is controlled by a Thermal Vacuum Switch (TVS), or an EFE solenoid controlled by the ECM. When vacuum is applied, the valve closes, causing the intake to heat up.

The electrical type of EFE uses a ceramic heater grid located underneath the primary base of the carburetor, as part of the carburetor insulator gasket. When the engine coolant is below a calibrated value, electrical current is supplied to the heater. This is accomplished with an ECM controlled relay.

When the temperature switch or relay turns on, the heater increases temperature and self-regulates at a calibrated temperature, until engine coolant reaches a calibrated value and the circuit opens.

Results of Incorrect EFE Operation:

No EFE when cold:

EFE stays on:


Table of Contents Top of Chapter

Copyright © 1998-2017 by The Members of The Oldsmobile Mailing List. All Rights Reserved. This web site is not affiliated with General Motors or Oldsmobile. General Motors and Oldsmobile are trademarks of their respective companies. The owners and members of this site are not responsible for errors or inaccuracies.