See Figures 1 and 2
The EFE system is used on some engines to provide a source of quick heat to the engine induction system during cold driveaway. There are two types of EFE systems: the vacuum servo type (located in the exhaust manifold) and the electric grid type (located under the carburetor).
The vacuum servo type consists of a valve in the exhaust manifold and a EFE control solenoid valve which is controlled by the ECM.
The electrical type consists of an electrical grid plate, mounted directly under the carburetor. The ECM controls the grid plate voltage by way of an EFE relay.
Both types are designed to produce rapid heating of the intake manifold, providing quick fuel evaporation and a more even distribution of fuel to aid in cold engine operation.
Every 30,000 miles, check the EFE valve (make sure it is free, not sticking) and the hoses for cracking or deterioration. If necessary, replace or lubricate. Check the electrically heated grid for meltdown and replace as necessary.