Abstract: To restore the efficiency of a platinum catalyst used for engine exhaust purification that has temporarily deteriorated through oxidation, the stoichiometric air-fuel ratio, or an air-fuel ratio set to a richer value than the stoichiometric air-fuel ratio of the air-fuel mixture supplied to the engine, is applied. The engine running condition and a decrease of catalyst oxidation are detected, and a recovery treatment temperature depending on the degree of oxidation is set. An engine running condition range suited to performing recovery treatment is set based on this recovery treatment temperature. By determining whether or not the running condition is within this range and applying a recovery treatment air-fuel ratio, recovery treatment is performed only under conditions satisfying the recovery treatment temperature. Recovery treatment is therefore performed efficiently, while increase of fuel costs and worsening of exhaust gas composition due to recovery treatment at low temperature are kept to a minimum.

Abstract: A fuel gauge system is disclosed, which includes a first device capable of visually indicating the amount of the mixed fuel in the container; a second device for detecting a real amount of the fuel in the container; a third device for detecting the mixing ratio of compositions in the mixed fuel; a fourth device for determining a critical effective amount of the mixed fuel in accordance with the fuel mixing ratio detected by the third device; a fifth device for judging whether the real amount is less than the critical effective amount or not; a sixth device for determining, based on the fuel mixing ratio detected and the real amount, a value corresponding to a calorific power possessed by the mixed fuel in the container; and a seventh device for controlling the first device in such a manner that, when the real amount is less than the critical effective amount, the first device indicates the value corresponding to the calorific power possessed by the mixed fuel in the container, and when the real amount is not

Abstract: A fuel delivery control apparatus for use with an engine operable on either of gasoline fuel and gasoline/alcohol fuel blend. The amount of fuel metered to the engine is controlled based upon engine operating conditions. A first correction factor is set at a value calculated based upon a signal from an alcohol concentration sensor to correct the amount of fuel metered to the engine. A second correction factor is set based upon a signal from an oxygen sensor to correct the amount of fuel metered to the engine so as to provide an air/fuel ratio feedback control. In the event of failure of the alcohol concentration sensor, the first correction factor is estimated by modifying it based upon the signal from the oxygen sensor and a difference between the calculated and estimated values of the first correction factor is calculated.

Abstract: If an alcohol sensor which determines the amount of alcohol which is mixed with gasoline, malfunctions, the fuel supply correction factor which is designed to modify the basic fuel supply amount to compensate for the amount of alcohol, is prevented from being changed in accordance with the output of the alcohol sensor, and temporarily calibrated by feedback from the air-fuel ratio sensor disposed in the exhaust system.

Abstract: An apparatus for use with an internal combustion engine operable on either of gasoline fuel, alcohol fuel and gasoline/alcohol fuel blend. The apparatus comprises an alcohol concentration sensor for producing a signal indicative of an alcohol concentration of the fuel to be delivered to the engine, an oxygen sensor for producing a signal indicative of an oxygen content of exhaust gases discharged from the engine, and an engine coolant temperature sensor for producing a signal indicative of an engine coolant temperature. A control unit is coupled to the alcohol-concentration, oxygen and engine-coolant-temperature sensors. The control unit is responsive to the air/fuel ratio feedback signal for correcting the fuel supplied to the engine to maintain a desired air/fuel ratio when the sensed engine coolant temperature exceeds a predetermined value.

Abstract: In an A/F ratio sensor of mixture supplied for an internal combustion engine, which has a detector for detecting the concentration of residual oxygen in exhaust gas and determines the A/F ratio by retrieving an air excess ratio table with an output of the detector, there is further provided an additional air introducing device, which introduces a predetermined quantity of air into the engine for a certain period of time, under the condition that the velocity of air flowing through a throttle valve is equal to the sonic velocity. The oxygen concentration detector is calibrated by the comparison of the outputs thereof before and after introduction of the additional air. According to this invention, the A/F ratio of the mixture can be detected accurately without the influence of the aged deterioration of the oxygen concentration.

Abstract: A first temperature sensor senses the temperature of intake air supplied to an internal combustion engine before the intake air is mixed with fuel supplied thereto. A second temperature sensor senses the temperature of the mixture of the intake air and fuel within the intake air passage. A control unit controls the fuel injection quantity in accordance with the difference between the sensed temperatures, thereby causing the actual air-fuel ratio to coincide with a desired air-fuel ratio. The desired air-fuel ratio is adjusted in accordance with the throttling effect of a throttle valve in the intake air passage and with engine speed.

Abstract: A variable venturi carburetor comprises an auxiliary intake air passage, an auxiliary variable venturi and a non-adjustable nozzle portion, in addition to a main intake air passage, a main variable venturi and an adjustable nozzle portion. If the amount of intake air is small as when the engine is being idled, intake air is passed mainly through the auxiliary variable venturi to generate vacuum sufficiently high to jet fuel into the auxiliary intake passage through the non-adjustable nozzle portion. If the amount of intake air is great as when the engine is running under a heavy load, intake air is passed mainly through the main variable venturi. Since two venturis are formed, it is possible to smoothly increase the amount of fuel to be jetted into the intake passage over a wide engine operating condition.