Abstract: In an engine management system which stores a control value and increments or decrements this according to whether an oxygen sensor in the exhaust system indicates that the engine is running lean or rich and which controls the duration of pulses applied to fuel injectors of the engine according to the stored control value, a compensating adjustment is determined and applied to the pulse length duration in order to maintain the mark/space ratio of the indicating signal from the oxygen sensor at an optimum value. This avoids unacceptable exhaust emissions which might otherwise occur under some conditions.

Abstract: An electronic fuel injection control includes a main fuel control circuit, a transient enrichment control circuit temporarily increasing fuel flow as a result of increasing of a demand signal, and temperature compensation means non-linearly varying the effect of the enrichment control with engine temperature. The temperature compensation means preferably includes a temperature "window" detector which acts to increase the effect of the enrichment control whenever the engine temperature is between prescribed limits.

Abstract: An electronic fuel injection control includes a main fuel control circuit which operates to control fuel flow to the engine by controlling the duration of engine-synchronized fuel valve opening pulses in accordance with at least one engine parameter. An auxiliary pulse source is arranged to provide extra unsynchronized pulses to improve the acceleration characteristics of the control, such pulses being produced when the throttle is opened. A muting circuit is provided which operates for a fixed period following closing movement of the throttle, to prevent the auxiliary pulse source responding to throttle opening during said period. The muting circuit prevents excess fuelling during gear changes etc.

Abstract: An electronic fuel injection control includes a main control circuit which controls fuel flow to the engine by controlling the duration of pulses applied to fuel valves. In addition there is a transient fuel varying control including a differentiating circuit which differentiates the signal from a throttle position transducer. This differentiator controls a variable frequency clock which forms part of the main fuel control so that the pulse duration is lengthened or shortened for a given value of the engine parameter which controls the main fuel control according to the rate of increase or decrease of the throttle position signal.