General

The EEC-IV system provides accurate, instantaneous fuel metering control of fuel injection timing and duration. A potentiometer which senses the position of the vane airflow meter in the engine's air induction system, generates a voltage signal that varies with the amount of air drawn into the engine. A sensor in the area near the vane airflow meter measures the temperature of incoming air and transmits a corresponding electrical signal. Another temperature sensor, inserted into the engine coolant system, gives information on engine temperature. A switch senses throttle plate position and produces, then transmits an electrical signal to tell the control unit when the throttle is closed or in the wide-open position. An oxygen sensor in the exhaust manifold measures the amount of free oxygen remaining in the exhaust gas, which is an indication of cylinder combustion efficiency, and sends a corresponding signal to the control unit. Crankshaft position information is transmitted by a sensor integral with the distributor.
The EEC-IV microcomputer circuit processes the input data from these sensors and produces output control signals to the fuel injectors, regulating precise fuel discharge through the injector nozzles. The microcomputer circuit also produces output signals that adjust ignition spark timing to provide a best balance between driveability and fuel economy.
The EEC-IV system also controls exhaust gas recirculation (EGR), A/C compressor cutoff at wide open throttle, knock control to eliminate detonation under adverse driving conditions, and wastegate control which regulates turbocharger boost pressure. The EEC-IV also controls fuel mixture on feedback carbureted engines.
The operating principles of all EEC-IV systems and related components are essentially the same. However, in adapting the EEC-IV system to different engines, different combinations of components are required.