Early Fuel Evaporation ( EFE ): Description and Operation

Cold Mixture Heater System Schematic:

CMH System Operations Chart:

The cold mixture heater (CMH) is an ECU controlled intake manifold heater that accelerates vaporization of liquid fuel during cold engine operation. The ECU uses the coolant temperature sensor signal and charging signal from the alternator to activate the CMH relay. The CMH relay applies battery current to the heater element in the intake manifold and the fuel heater in the carburetor float bowl. By preheating the air/fuel mixture, HC and CO are reduced during cold engine warm-up. The CMH relay is deactivated after engine coolant temperature reaches 140°F.