In an internal combustion engine, fuel injection is stopped to automatically stop the engine when automatic stop conditions are met. When there is a request to restart the engine while an engine speed is decreasing due to automatic stoppage, the engine is started by resuming fuel injection if the engine speed is equal to or greater than a combustion recoverable rotational speed threshold, at which restarting is possible only by fuel injection. When there is a request to restart the engine while an engine speed is decreasing due to automatic stoppage, the engine is started using a starter motor if the engine speed is less than the combustion recoverable rotational speed threshold. When there is a request to restart the engine in a brake ON state, the engine is not started by resuming fuel injection, but rotated and started using the starter motor.

A first controller includes a start control section and a passage determination section. After activating a second starter to start cranking, the start control section stops the operation of the second starter and starts the motor operation of the first starter at a predetermined timing. The passage determination section determines whether a predetermined passage conditional expression holds after cranking is started by the second starter. The start control section stops the operation of the second starter and starts the motor operation of the first starter if the passage conditional expression holds before the engine passes the first compression top dead center, regardless of whether the engine has passed the first compression top dead center.

A vehicle includes a controller programmed to activate a fuel savings feature upon satisfaction of transition conditions and inhibit the transition according to satisfaction of inhibit conditions. The controller is further programmed to accumulate data indicative of the inhibit conditions and a time associated with the conditions being satisfied over a drive cycle.

Methods and systems are provided for dealing with a change of mind event during an automatic shut-down of an engine in which the speed at which a starter motor used to restart the engine is disengaged is based upon the comparison of current engine speed (N) with a cranking speed limit (S.sub.LIM). In one example, during an engine restart while the engine is spinning down, the starter motor may crank the engine to a threshold cranking engine speed adjusted based on a position of the gear.

A vehicle control device configured to be capable of executing idle stop control to automatically stop an engine when a predetermined automatic stop condition is satisfied and restart the engine when a predetermined restart condition is satisfied during the automatic stop of the engine, the vehicle control device includes: a start request detector, a shift position detector, and a delay time setting module. A start request detector detects a driver operation indicating a request for starting the engine by a driver. A shift position detector detects a shift position of a shift changer. A delay time setting module sets, on a basis of presence or absence of the driver operation and the shift position, a delay time from when the engine is restarted until when an automatic stop of the engine is permitted.

In response to a restarting request generated during a stopping period, in which fuel injection is stopped to automatically stop engine operation, either starter starting or combustion starting is selected. In the starter starting, the engine is restarted using a starter motor. In the combustion starting, the engine is restarted through fuel injection and ignition without using the starter motor. If the rotational resistance acting on the crankshaft is determined to be of such a magnitude that the combustion starting is impossible, the starter starting is carried out in response to the restarting request generated during the stopping period.

An internal-combustion engine includes a belt-driven starter generator and makes an idling stop while a vehicle is at a stop. In the process of the engine revolution speed decreasing with cutting of fuel to stop the vehicle, to suppress the reduction in restart responsiveness caused by slack in a belt, preliminary powering of the starter generator is performed. The belt tension during deceleration microscopically changes periodically between a relatively high-tension period and a relatively low-tension period due to pulsation of the engine revolution speed. Slack in the belt does not occur in the high tension period, and thus preliminary powering torque is applied only in the low-tension period.

A stop-start system and method for a motor vehicle include a controller configured to shut down an engine of the motor vehicle automatically when the motor vehicle is moving and a predetermined engine shut down condition is achieved, to perform a rolling stop-start operation; and a mechanically driven auxiliary vacuum pump coupled to a transmission gear or output shaft and configured to provide vacuum pressure to a brake booster of the motor vehicle, wherein the controller is configured to operate the auxiliary vacuum pump during the rolling stop-start operation.

In the case of restarting an internal combustion engine that has been automatically stopped during running, the internal combustion engine is restarted by combustion recovery starting when the rotation speed of the internal combustion engine under the input of a restart request is greater than or equal to a predetermined first rotation speed. In the case of restarting the internal combustion engine that has been automatically stopped during running, the internal combustion engine is restarted by cranking recovery starting when the rotation speed of the internal combustion engine under the input of the restart request is lower than the predetermined first rotation speed. The first rotation speed is set lower at the restart of the internal combustion engine in a sailing stop state than at the restart of the internal combustion engine in a coast stop state.

Systems and methods for operating an internal combustion engine that may be automatically stopped and started are described. In one example, an engine is rotated in a reverse direction after an engine stop so that a belt integrated starter/generator may rotate the engine in a forward direction and utilize the inertia of the engine to rotate trough top-dead-center compression stroke, thereby starting the engine.