When a predetermined restart condition is satisfied after an engine is automatically stopped, whether or not a piston of a stopped-in-compression-stroke cylinder which is in a compression stroke falls within a specific range set at a bottom dead center side of a predetermined upper limit position is determined. When the piston of the stopped-in-compression-stroke cylinder falls within the specific range, a first compression start is executed in which fuel is injected from an injector into the stopped-in-compression-stroke cylinder for the first time and is then self-ignited. In the first compression start, a start timing of a first fuel injection operation with respect to the stopped-in-compression-stroke cylinder is set to be earlier as a stop position of the piston of the cylinder gets closer to the bottom dead center within the specific range.

Methods and systems are provided for detecting leaks in an intake manifold of an engine. In one example, a method may include closing all intake valves of all cylinders of the engine during an engine shut down responsive to vacuum in the intake manifold reaching a pre-determined vacuum level. The method may further include indicating a leak in the intake manifold responsive to a change in a level of vacuum in the intake manifold after closing all the intake valves of all cylinders.

Methods and systems are provided for detecting leaks in an intake manifold of an engine. In one example, a method may include closing all intake valves of all cylinders of the engine during an engine shut down responsive to vacuum in the intake manifold reaching a pre-determined vacuum level. The method may further include indicating a leak in the intake manifold responsive to a change in a level of vacuum in the intake manifold after closing all the intake valves of all cylinders.

Embodiments for an internal combustion engine are provided. In one example, and internal combustion engine comprises at least two cylinders each including an injection nozzle and a fuel supply system for supplying the cylinders with fuel. The fuel supply system includes a supply line connecting each injection nozzle to a first fuel reservoir storing fuel at a first pressure, the first fuel reservoir filled by a pump provided upstream, a second fuel reservoir storing fuel at a second pressure less than the first pressure and connected to the first fuel reservoir via a connecting line for filling with fuel, and a bypass line connecting the second fuel reservoir to each injection nozzle. The bypass line opens into the fuel supply system downstream of the first fuel reservoir, thereby forming a connection point, and a shutoff element is arranged in the bypass line, opening or shutting off the bypass line.

An estimation apparatus, includes: a sensor, disposed in the proximity of a crank rotor, configured to output a signal in response to a positional variation of an outer periphery of the crank rotor, the crank rotor including a plurality of protruding teeth formed at given distances and a tooth-missing region on an outer periphery of the crank rotor and configured to rotate in an interlocking relationship with a crankshaft of an internal combustion engine; and a processor configured to calculate a crank angular velocity of the internal combustion engine at given time intervals from the signal output from the sensor and estimate a first crank angular velocity corresponding to the tooth-missing region from second crank angular velocities at two or more points corresponding to at least one of portions before and after the tooth-missing region.

A start control apparatus is provided with: a crank angle sensor configured to output a signal in association with rotation of an output shaft of an internal combustion engine; a resolver configured to detect a rotor angle, which is an angle position of a rotating shaft of a motor; and a controlling device configured to perform start control associated with the internal combustion engine on the basis of a temporary crank angle, from a start of the internal combustion engine until determination of a crank angle in starting of the internal combustion engine, wherein the temporary crank angle is an estimated value calculated by adding a value according to the outputted signal to a stop angle, which is an angle based on the rotor angle detected at a previous stop of the internal combustion engine.

A method for determining an absolute angular position of a crankshaft target of an internal combustion engine, including a plurality of teeth for which at least one signal is acquired representing the passage of each tooth in front of a sensor as a function of time comprising: i. generating during a phase with the engine running an absolute angular position from the at least one signal and from a period of a tooth; ii. continuously determining during a phase of stopping the engine when determination of the period is not possible, a number of teeth passing in front of the sensor; and iii. during a phase of restarting the engine, using a number of teeth to reduce the cycle synchronization time.

A method for an engine is presented, comprising, following an engine-off event, positioning a first engine cylinder with an intake valve open, opening a canister purge valve; and purging contents of the first engine cylinder to a fuel vapor canister. In this way, uncombusted fuel that may otherwise be emitted from the engine during a prolonged diurnal soak may be stored within the fuel vapor canister, thus decreasing overall vehicle emissions.

An apparatus and a method for controlling an internal combustion engine, detects a rotating direction of an output shaft of the internal combustion engine. The internal combustion engine includes a crank angle sensor for outputting a pulse signal in accordance with rotation of a crankshaft. The crank angle sensor outputs at the time of reverse rotation of the crankshaft a pulse signal POS having a wider pulse width than that at the time of forward rotation. A control unit receiving pulse signal POS calculates a difference between a present value and a previous value of a pulse width of pulse signal POS and detects switching of a rotating direction of the crankshaft based on a magnitude of this difference. Thus, it is possible to suppress lowering of detection accuracy of a rotating direction of the crankshaft under the influence of variation of measurement values of the pulse width.

Systems and methods for restarting an engine are presented. In one example, fuel is injected to cylinder ports before the engine is stopped such that the injected fuel is not inducted into the cylinders before an engine restart is requested. The method may improve fuel vaporization during engine restarting.