Abstract: A predetermined control on an engine, i.e., a fuel-cut operation, is executed after an accelerator has been released under predetermined conditions when vehicle speed is higher than a fuel-cut vehicle speed value and engine speed is higher than or equal to a fuel-cut engine speed value. In an automatic transmission drivingly connected to the engine via a torque converter, a gear shift is initiated after the accelerator has been released. During a shift of the same kind, there occurs a variability in shift shock between the cases with and without the execution of the fuel-cut operation. In order to reduce this variability, the execution of the fuel-cut operation is inhibited until completion of the shift after the accelerator has been released under the predetermined conditions.

Abstract: A system and method for controlling an operation of an internal combustion engine of a vehicle having an automatic transmission in which at least one of predetermined fuel supply recovery engine revolution speed or predetermined fuel supply cut-off engine revolution speed is varied during the engine deceleration condition according to a state of operation of the automatic transmission. In the first preferred embodiment, a downshift operation of the automatic transmission is detected. In the second preferred embodiment, an overrun clutch solenoid is turned on (energized). In the latter case, both fuel supply recovery and fuel supply cut-off engine revolution speeds are set to higher values than those when the clutch solenoid is turned off (deenergized).

Abstract: A hydraulic pressure, i.e., a line pressure, of a hydraulic fluid supplied from an engine driven pump toward a hydraulically actuable coupling of an automatic transmission is held at the maximum pressure value when a temperature of an automatic transmission oil is less than a predetermined temperature value. However, the hydraulic pressure is temporarily decreased from the maximum pressure value to the minimum pressure value for a period of time after cranking of the engine when the transmission oil temperature is lower than the predetermined temperature value. Owing to a decreased load on the engine by the oil pump, smooth cranking and subsequent warming-up operation of the engine is assured under cold whether condition when the automatic transmission oil temperature is lower than the predetermined temperature value.

Abstract: In order to determine a malfunction which results in the loss of torque reduction control, the engine speed and the torque converter characteristics are monitored when a torque down signal is issued. The maximum engine torque which should be produced under such circumstances is used to derive a corresponding maximum engine speed value. If the actual engine speed exceeds the estimated value, appropriate torque down control can be assumed to have been lost. In response a fail safe such as boosting line pressure to switching to an alternative source of torque control can implemented. A suitable warning signal can also be generated.

Abstract: A unified control device for engine and automatic transmission of an automotive vehicles serves to alleviate a racing select shock which occurs upon engagement of a driving clutch in the transmission when selecting a running range of the transmission to start the vehicle with an accelerator pedal depressed. The control device achieves a reduction control during changeover of the transmission into a running range from a racing state, to reduce at least one parameter representing the output power to be transmitted from the engine to driving wheels via the transmission, such as engine speed, engine output and/or transfer torque capacity of the clutch, etc. The reduction control is stopped as soon as the completion of engagement of the driving clutch has been detected, to allow the vehicle to be started without engine stalling.

Abstract: A system and method for controlling an engine revolution speed are disclosed in which upon a reduction in coolant temperature, a control signal is supplied to an idling control valve having a duty ratio reducing the duty ratio corresponding to the opening angle of the idling control valve when an engine coolant temperature is below a predetermined value so that during an engine deceleration in which an air regulator is open, an increase in a boost pressure is prevented and no reduction of the engine revolution speed occurs or engine revolution speed during the idling does not become excessively high.

Abstract: A system and method for controlling ignition timing for an internal combustion engine having cylinder bank rows are disclosed in which the ignition timings for the cylinders belonging to one of the cylinder banks determined according to engine load and engine revolution speed and are corrected according to differences in the ignition timings for the cylinders of both cylinder bank rows so as to eliminate variations in the ignition timings between each cylinder bank row. The crank angle sensor of the ignition timing control system is installed on at least one camshaft for either exhaust or suction valves on an overhead cam at one of the cylinders belonging to either of the cylinder bank rows.

Abstract: An ignition timing adjusting apparatus of an internal combustion engine is provided so as to suppress the vibration of the body of a vehicle when it is accelerated. This is achieved by obtaining a first ignition timing compensation magnitude determined on the basis of the revolution speed fluctuation of the internal combustion engine and a second ignition timing compensation magnitude determined on the basis of the engine load condition, and by compensating a basic ignition timing in accordance with the first and second ignition timing compensation magnitude when the vehicle is accelerated.

Abstract: An improved system and method for controlling an engine idling speed for an internal combustion engine are disclosed in which an electromagnetic valve for controlling fluid flow quantity passing through a bypass passage of an engine throttle valve is provided, a water jaket for circulating an engine cooling water is provided so as to surround a coil portion of the electromagnetic valve. The change characteristic of the fluid flow quantity for the electromagnetic valve is varied according to the engine cooling water temperature, and both an optimum target idling speed and feedback control coefficients in a control variable of an opening angle of the electromagnetic valve, i.e., a voltage duty ratio applied to the electromagnetic valve are varied according to the engine cooling water temperature.