Abstract: An electronic fuel injection (EFI) control system (10) for an internal combustion engine. The EFI control system (10) is disclosed in conjunction with a compression ignition engine (12) where the parameters of fuel quantity (446) and injection timing (460) are controlled on the basis of a plurality of engine operating conditions. The parameter of fuel quantity (446) is obtained from a comparison of computed values of percent load fuel quantity (428) and full load fuel quantity (444) with the lesser of the two being selected. The percent load fuel quantity (428) has a proportional component (416) that is a function of actual engine speed (414) and commanded engine speed (412), and an integral component (426) that is related to cumulative speed error (422). The full load fuel quantity (444) is a function of actual engine speed (414) and manifold air density (436). The parameter of injection timing (460) is obtained from a summation of two computed quantities for injection advance.

Abstract: A driver circuit for electronically actuating in a predetermined sequence, a plurality of solenoids (54). The driver circuit includes a single boost circuit (22) having an inductor (118) for receiving energy from a power supply and a capacitor (110) for storing a portion of this electrical energy prior to activation of a particular solenoid. The driver circuit further includes circuitry associated with each solenoid (40, 80, 82, 84) for energizing the solenoid by causing the capacitor (110) to discharge therethrough and to regenerate the stored voltage potential prior to the time for energizing another solenoid, The drive circuit further includes a current regular and mode control (70, 150, 170) to control the magnitude of current flowing through each solenoid.