In an internal combustion engine system, a controller is configured to: perform a purge control during execution of an A/F feedback learning; detect a purge concentration after execution of the A/F feedback learning; calculate an A/F feedback learning correction value adjusted by offsetting an A/F feedback learning value with a contributing value of the purge concentration; disable updating of the A/F feedback learning correction value after calculation of the A/F feedback learning correction value and until the purge control is stopped; and detect the purge concentration based on an air-fuel ratio deviation amount.

A fuel tank vent system includes a venting apparatus for regulating discharge of fuel vapor from a fuel tank and admission of outside air into a fuel tank. The vent valve is used to regulate pressure in a fuel tank.

A method for controlling an air-fuel ratio in an idle purge-off mode is provided. The method includes stopping feedback for an amount of fuel for a particular period of time when idle purging is terminated and performing freeze control with a constant lambda control value.

Various embodiments include method comprising: determining a torque of each cylinder resulting from an injection; determining a difference in the respective torque output; determining a progression of a pressure in one of the cylinders within a cycle; determining a progression of the crankshaft speed within the cycle; determining a time interval between a maximum the pressure and a subsequent maximum of the speed within the cycle; comparing the difference in the torque outputs with a threshold; if the difference exceeds the threshold, determining a progression of the crankshaft speed for each of the cylinders within a respective cycle and determining the respective maxima; determining a respective time of the maxima within the associated cylinder cycle; determining a difference between the respective maxima; and if the difference is greater than a predetermined threshold, changing an injection time in one of the cylinders based on the determined time interval.

A method for diagnosing a purge valve of a canister purge system includes (a) determining whether a purge valve, which is installed on a purge pipe connecting a canister with an intake system of an engine, is open and whether a purge pump is running, wherein the purge pump is configured to pump evaporative emission captured in the canister toward the intake system, and (b) determining whether the purge valve is in a close stuck state, based on upstream pressure and downstream pressure of the purge pump, when the purge valve is open while the purge pump is running.

A returnless fuel supply system applicable to an LPG vehicle is provided. The system supplies LPG fuel from an LPG bombe to an engine at a predetermined pressure or greater and prevents the generation of vapor in the LPG fuel, thereby eliminating a need to return a portion of the LPG fuel supplied to the engine to the LPG bombe. Through the application of the returnless fuel supply system that does not return the high temperature fuel to the LPG bombe, the cause of the internal pressure increase in the LPG bombe is eliminated, and thus efficient refueling of LPG bombe with LPG fuel is achieved.

An engine-driven working machine according to the present invention has a controller and a muffler. The controller is operated from starting of the engine in a rotational speed limitation mode in which the engine is prevented from rotating at a rotational speed that is higher than the predetermined limitation rotational speed. The controller forces to stop the engine, after a predetermined period has passed, during which the engine operates in the rotational speed limitation mode.

An engine-driven working machine according to the present invention has a controller and a muffler. The controller is operated from starting of the engine in a rotational speed limitation mode in which the engine is prevented from rotating at a rotational speed that is higher than the predetermined limitation rotational speed. The controller forces to stop the engine, after a predetermined period has passed, during which the engine operates in the rotational speed limitation mode.

A method for operating an internal combustion engine having a number of cylinders and an injection system having an injection system that has a common rail and a number of injectors associated with the cylinders, wherein an individual accumulator is associated with each injector and stores fuel from the common rail for the injector. The method has the following steps: starting the internal combustion engine, operating the internal combustion engine, shutting off the internal combustion engine. The following steps are also provided: a state indicating an engine standstill is detected, in particular after the internal combustion engine has been shut off, a high-pressure limit value is defined and a target high pressure is specified, a leakage is produced in the common rail without injection, the fuel pressure in the common rail is reduced to the defined high-pressure limit value below the target high pressure by way of the leakage.

Various embodiments may include a method for operating a piezo-actuator in a piezo-operated injector for a fuel injection system comprising: producing a measuring pulse at a position at which the usable signal which is to be measured is expected; then producing a reference pulse which corresponds to the measuring pulse, in the same cycle; subtracting a first actuator voltage measured during the reference pulse from a second actuator voltage measured during the measuring pulse; using a resulting voltage signal difference to calculate a force sensed by the piezo-actuator; and using the force sensed to correct an injection amount for the injector.