Abstract: An air-fuel ratio controller of an internal combustion engine stops current flow of an oxygen pump and power supply to an heater when the engine stops.In one embodiment the A/F ratio controller related to the invention stops power supply to the heater a predetermined period of time after the engine stops.

Abstract: An air-fuel control apparatus comprises an air-fuel ratio sensor comprising a gap portion for introducing exhaust gas generated from an engine, a solid electrolyte oxygen pump for controlling a partial pressure of oxygen in the gap portion and a solid electrolyte oxygen sensor producing an electromotive force in response to a proportion of the partial pressure of oxygen in the gap portion and a partial pressure of oxygen in other than the gap portion.

Abstract: An air-fuel (A/F) controller of an internal combustion engine, which computes an average value of a plurality of duty ratios of the voltage supplied to the heater according to the engine speed and the engine load periodically detected during a period from a predetermined moment up to the present, and fixes said average value as the present duty ratio of the voltage to be supplied to the heater, since the A/F ratio sensor is heated not only by the heater but also by exhaust gas. The A/F ratio controller smoothes the variation of voltage to be supplied to the heater by applying the computed average value as the present duty ratio of the supply voltage which is to be supplied to the heater. Accordingly, even when the driving condition is in high-speed, variation of the temperature borne by the heater is mild and smooth, and thus, the temperature of the oxygen-concentration detecting element does not rise suddenly.

Abstract: Techniques are provided for controlling the operation of an air-fuel ratio control apparatus for an internal combustion engine including feedback control of the air-fuel ratio control. The pump-driving voltage for flowing the pump-driving current used for changing the oxygen concentration is monitored and feedback control is suspended when the pump-driving voltage departs from a predetermined range.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine comprises feedback control of the air-fuel ratio control, wherein a pump-driving voltage for flowing a pump-driving current is lowered to a predetermined value, and feedback control is suspended when the pump-driving current becomes lower than a predetermined value.

Abstract: In an engine speed control method including detecting a signal representing an error between an actual engine speed and a desired idling speed, and controlling both an ignition timing of an engine according to the error signal and an intake air quantity or an air/fuel mixture quantity to be sucked into the engine in order to make an engine speed to the desired engine speed; the improvement comprising the step of correcting the intake air quantity and the air/fuel mixture quantity to the engine according to an ignition timing error signal representing an error between an actual ignition timing of the engine and an ignition timing predetermined in accordance with an engine operation condition.

Abstract: In a fuel control apparatus for an n-cycle engine, when a cylinder discriminating means detects a value obtained by counting turning angle position signals is out a predetermined range, or when a detecting means detects that data of cylinder do not have values according to a predetermined order, a fuel-injection control means performs simultaneous injection of fuel to all cylinders, and thereafter the fuel injection is prohibited until the cylinder discriminating means detects a specified cylinder among the six cylinders.