Abstract: A fuel metering control system for an internal combustion engine, having a feedback loop. In the system, the quantity of fuel injection (Tim) to be supplied to the engine (plant) is determined outside of the feedback loop. A first feedback correction coefficient (KSTR) is calculated using an adaptive law, while a second feedback correction coefficient (KLAF(KSTRL)), whose control response is inferior to the first feedback correction coefficient is calculated, using a PID control law. The feedback correction coefficients are calculated such that the plant output (air/fuel ratio) is brought to a desired (desired air/fuel ratio). A Variable(s) of one coefficients is replaced with a value of the other coefficient such that the one coefficient becomes close to the other. Moreover, the second coefficient (KLAF(KSTRL) is used at a time of returning from open-loop to the feedback control.

Abstract: Air/fuel and ignition control of engine (28) are used to more rapidly heat-up a catalytic converter (52). A control system (8) generates a fuel command (100) for fuel delivery to the engine (28) based upon at least an amount of air inducted into the engine. The fuel command is offset by a predetermined amount in a lean direction during a period after engine start to shift the engine exhaust gas mixture towards a preselected air/fuel ratio lean of stoichiometry (106-122). In addition, the fuel command is corrected by a correction value so that the exhaust gas mixture is shifted ore closely to the preselected air/fuel ratio (126-140). Correction values are adaptively learned (300-324) during a portion of the warm-up period from a feedback signal derived from an exhaust gas oxygen sensor (44). Ignition timing and engine idle are also controlled (350-374) to further achieve more rapid warm-up of the catalytic converter (52).

Abstract: A fuel supply control system for an automotive engine determines a property of the fuel, such as the fifty percent distillation temperature T.sub.50 thereof, and the fuel injectors of the engine are controlled in accordance with the determined fuel property. When the engine is idling and the coolant water temperature WT of the engine is decreasing, the amplitude X of the feedback correction factor K.sub.2 for proportional-plus-integral control action is measured a number of times, and an average amplitude X.sub.0 thereof is calculated. The property of said fuel is determined on the basis of the thus calculated average amplitude X.sub.0 and the coolant water temperature WT using a two-dimensional map which gives the value of T.sub.50 as a function of the amplitude X of the feedback correction factor K.sub.2 and the coolant water temperature WT. The thus determined index T.sub.50 is stored in a RAM backed up by a battery. When a new fuel is supplied to the fuel tank, the value of index T.sub.

Abstract: An air-fuel ratio control system for an engine, to which evaporated fuel in a canister is supplied, is used for feedback controlling an air-fuel ratio based on a feedback control value calculated according to the quantity of evaporated fuel supplied to the engine. A calculation is made, in a first range of engine operating conditions, of a difference of a first control value between the first control value determined during supplying of the evaporated fuel to the engine and the first control value determined during not supplying of the evaporated fuel to the engine in the first range. A second control value for a second range of engine operating conditions is established different from the first range based on a feedback control value for controlling an air-fuel ratio of fuel in the first range, a ratio of the quantity of intake air into the engine between the first and second ranges, and a ratio of the supplying quantity of the evaporated fuel into the engine between the first and second ranges.

Abstract: An air-fuel ratio control system for an internal combustion engine utilizes a pre-stored standard relation between an air-fuel ratio sensor signal and a standard air-fuel ratio indicative value for deriving the standard air-fuel ratio indicative value based on the sensor signal. The system further utilizes a pre-stored modified relationship between the standard air-fuel ratio indicative value and a for-control air-fuel ratio indicative value for deriving a for-control air-fuel ratio indicative value based on the derived standard air-fuel ratio indicative value. In the modified relationship, the for-control air-fuel ratio indicative value varies with respect to a corresponding variation of the standard air-fuel ratio indicative value within a given range across the standard air-fuel ratio indicative value representing a stoichiometric air-fuel ratio.

Abstract: An electronic fuel injection system operable as a bolt on retro fit replacement for a wide variety of carburetors is disclosed. The system includes a throttle body-injector assembly which, by means of an adapter may be bolted directly to stock intake manifolds using the carburetor mounting bolt holes in the manifold. The throttle body passages and injectors are designed to meet the fuel and air delivery requirements of large displacement engines and an electronic control unit which controls the solenoid actuated injectors in a duty cycle operation is provided with externally accessible adjustments by means of which the system may be adjusted to tune the rate of fuel injection to the fuel delivery requirements of engines of displacements much smaller than the largest displacement engine within the systems capability.

Abstract: An air-fuel ratio control system for an internal combustion engine controls the air-fuel ratio of a mixture supplied to the engine to a desired air-fuel ratio in response to an output from an exhaust gas ingredient concentration sensor. A first value of the desired air-fuel ratio is calculated based on the rotational speed of the engine and the load on the engine. A second value of the desired air-fuel ratio is calculated based results of determination on whether a vehicle on which the engine is installed has just started from a standing position thereof. A third value of the desired air-fuel ratio is calculated based on results of determination on whether the temperature of the engine is lower than a predetermined value. The largest value of at least the first to third values of the desired air-fuel ratio is set to a final value of the desired air-fuel ratio.

Abstract: An air-fuel ratio control system for an internal combustion engine, which detects the actual air-fuel ratio of a mixture supplied to the engine, detects operating conditions of the engine, calculates a desired air-fuel ratio based on the detected operating conditions of the engine, and calculates an air-fuel ratio correction value applied for feedback-controlling the actual air-fuel ratio to the calculated desired air-fuel ratio. A change rate at which the air-fuel ratio correction value is to be changed, is set such that when a change has occurred in the operating mode of the engine, the change rate is set to and held at a smaller value than a value assumed when no change has occurred in the operating mode, over a predetermined time period from the time the change occurred.

Abstract: In an internal combustion engine where in a predetermined driving state, the air-fuel ratio is feedback-controlled based on a detection signal of an air-fuel ratio sensor and in other driving state, the air-fuel ratio is feed-forward-controlled, the presence or absence of a misfire is judged from the detection signal of the air-fuel sensor at the time of the feed forward control, and when the presence of a misfire is judged, a warning is given.