California Vehicles (Digifant I)

Digifant I Engine Management System:

The Digifant I engine management system combines control of the electronic port fuel injection and the TCI-h/knock ignition systems in a single control unit. All functions of the fuel, ignition, and idle speed stabilization systems are carefully controlled throughout the entire range of engine speed, engine load, and temperature conditions to produce maximum fuel efficiency and engine performance.

The air flow sensor, air intake sensor, coolant temperature sensor, Hall sender, throttle valve potentiometer, oxygen sensor, and knock sensor provide the Digifant I control unit (ECU) with information concerning engine operating conditions. Based on the this information, the Digifant I control unit determines the appropriate output signals for injector pulse width, ignition timing point, and idle stabilization. The ECU also receives a signal from the A/C compressor clutch when activated. This additional input prevents the severe dip in idle speed resulting from the additional load before the idle stabilization system can compensate.

The Digifant I system adjusts operating ranges for the air/fuel ratio, idle speed, and altitude changes automatically. Because of this "adaptive" quality, the need for periodic adjustments due to minor vacuum leaks, and normal engine wear is largely eliminated.

An On-board diagnostic system provides fault recognition and diagnosis for the Engine Management System. The E.C.U. monitors normal operating conditions, detects unusual values and other recognized faults, and stores the fault information in an eraseable permanent memory for later retrieval. Faults that could cause the vehicle to fail an exhaust emission inspection will illuminate the "CHECK" light on the instrument panel and must be erased after corrective procedures have been completed.

NOTE: Because of its adaptive capability, the Digifant I control unit MUST be returned to its reference settings IF:

1. The coolant temperature sensor (blue connector) has been disconnected while the engine is running.

2. Any of these components have been replaced:
^ Digifant I control unit
^ Air flow sensor
^ Throttle valve potentiometer
^ Throttle body

Adjustments