Feedback Control System
Carburetor Feedback Control (FBC) system maintains a controlled air/fuel ratio which allows catalyst to reduce HC, CO, and NOx in addition to providing better driveability and fuel economy. Exhaust gas is monitored by an Electronic Control Module (ECM) by way of an exhaust manifold mounted Oxygen (O2) sensor. ECM processes O2 sensor signal and adjusts air/fuel ratio through a mixture control solenoid in the carburetor.
The ECM, located under the glove box, controls fuel-cut system, idle-up system, bowl vent system, EGR system and secondary throttle valve system, as well as the feedback system.
ECM controls this function through the following received signals: O2 sensor, engine coolant temperature (thermal) switch, throttle position (wide open and idle) switch, engine speed, electrical load, gear position, altitude compensation and engine compartment temperature. See Fig 1 .