Abstract: A fuel mixture control apparatus for an electronic fuel injection system for internal combustion engines. In a warm-up controller, the fuel injection control pulses are lengthened for enrichment of the fuel-air mixture during engine warm-up on the basis of signals supplied by a temperature transducer. In order to make the warm-up enrichment dependent on prevailing engine states, for example on the conditions of idling and partial or full load, circuitry is provided to sense these conditions and to suitably alter the enrichment factor. A further circuit suppresses the dependence or enrichment on engine status during engine starting. Various embodiments are presented.

Abstract: A fuel injection system which employs electromagnetic injection valves controlled by injection control pulses of variable width. When the engine is being operated in the overrunning condition, with closed throttle and elevated rpm, the normally provided fuel injection control pulses can be supplanted by substitute pulses of either constant or variable width. The apparatus includes a comparator circuit which determines whether the original control pulse is to be used or the substitute pulse. Several embodiments are presented.