Computers and Control Systems: Description and Operation

Fig. 1 Computer Controlled Emission Control (CCEC) System Operating Schematic:

The purpose of this system is to maintain a controlled air/fuel ratio, allowing the three-way catalyst to reduce oxides of nitrogen, hydrocarbons, carbon monoxide and to improve fuel economy simultaneously, Fig. 1.

The ECM and the oxygen sensor are provided in this system. The oxygen sensor is mounted on the exhaust manifold. It monitors the exhaust gas air fuel ratio and signals to the ECM.
The ECM receives the oxygen sensor signal, then controls carburetor air/ fuel ratio by the operation of the mixture control solenoid valve. Therefore, the signal of the exhaust gas air fuel ratio sensed by the oxygen sensor is fed back to ECM and carburetor air/fuel ratio is controlled.
The ECM controls the fuel cut system, idle-up system, bowl vent system, EGR system and secondary throttle valve system and feedback system. The ECM is located under the glove box.