Abstract: A vehicle is driven by an internal combustion engine having an air induction passage with an idle air control valve positionable by a stepping motor in response to valve opening and valve closing pulses. A counter normally counts the pulses arithmetically to provide an indication of valve position. In order to bring the counter and valve position into accord, counter reset apparatus is effective, when actuated, to generate a predetermined number of valve closing pulses sufficient to stall the stepping motor against the stop, reset the counter to a predetermined reference count and generate a predetermined number of valve opening pulses to return the idle air control valve to a desired operating position with the counter counting such pulses in the normal manner.

Abstract: Transient fuel control apparatus for an above the throttle fuel injected internal combustion engine includes apparatus effective to measure the time rate of change of throttle position and periodically derive therefrom a first transient correction number, apparatus effective to generate a first order lag filtered induction passage pressure signal, apparatus effective to derive rate of change of the induction passage pressure relative to the filtered induction passage pressure signal and derived therefrom a second transient fuel correction number and apparatus effective to modify the fuel injected into the induction passage from the quantity normally injected during steady state engine operation by an amount derived from the arithmetic sum of the first and second transient fuel correction numbers.

Abstract: Idle air control apparatus for a vehicle driving internal combustion engine having an air induction passage includes a control valve in the air induction passage controlled by a stepper motor in response to the arithmetic count of applied electrical pulses, a register effective to store a valve control number representing the currently desired position of the control valve, apparatus effective upon occurrence of a predetermined engine loading event to change the valve control number in response thereto, an up-down counter effective to arithmetically count the pulses applied to the stepper motor and thus indicate actual control valve position, a closed loop control effective to compare the contents of the up-down counter and register and apply pulses to the stepper motor at the first predetermined rate to reduce any difference therebetween and a speed trim loop active only during occurrence of a predetermined steady state idle condition to compare actual engine speed with the desired engine idle speed and arit

Abstract: The idle and main fuel passages of a carburetor are controlled by metering apparatus which is regulated to maintain the idle and part throttle air-fuel mixtures at a selected air-fuel ratio, but during low temperature engine operating conditions the part throttle mixture is leaner than the idle mixture in any particular regulated mode of the metering apparatus. This invention provides a mixture forming assembly which further includes means for leaning the idle mixture only during such low temperature operating conditions; the metering apparatus is then regulated to a rich mode at idle during low temperature engine operating conditions to provide an idle mixture which is leaned to the selected air-fuel ratio, and a lean part throttle mixture is avoided as the throttle is opened from idle to a part throttle position.

Abstract: A closed loop fuel control system is described for a vehicle internal combustion engine which includes an exhaust gas sensor providing a signal having a value determined by the oxidizing/reducing conditions of the exhaust gases. An integral controller is responsive to the output of the exhaust gas sensor and provides a control signal varying in a first direction for sensed oxidizing/reducing conditions greater than a desired condition and varying in an opposite direction for sensed oxidizing/reducing conditions less than the desired condition. A control circuit is responsive to the output of the integral controller to adjust the vehicle engine air/fuel supply device to vary the value of the air/fuel ratio of the mixture supplied to the engine in a direction tending to maintain the desired exhaust gas condition. The output of the integral controller is limited to predetermined values so as to limit the air/fuel ratio control authority of the closed loop circuit.