A sensor failure diagnostic apparatus includes a first estimation unit to estimate a mixing ratio of each type of a molecular structure included in a fuel, based on combustion parameters when a combustion of an internal combustion engine is executed in different combustion conditions, among the combustion parameters sensed by a combustion sensor, a second estimation unit to estimate the mixing ratio, based on characteristic parameters sensed by a characteristic sensor, a combustion sensor diagnostic unit to determine whether a failure of the combustion sensor exists, based on a sensed value of the combustion sensor when the combustion is not executed, and a characteristic sensor diagnostic unit to determine whether a failure of the characteristic sensor exists, by comparing the mixing ratio estimated by the first estimation unit with the mixing ratio estimated by the second estimation unit when the combustion sensor diagnostic unit determines the combustion sensor is normal.

A sensor failure diagnostic apparatus includes a first estimation unit to estimate a mixing ratio of each type of a molecular structure included in a fuel, based on combustion parameters when a combustion of an internal combustion engine is executed in different combustion conditions, among the combustion parameters sensed by a combustion sensor, a second estimation unit to estimate the mixing ratio, based on characteristic parameters sensed by a characteristic sensor, a combustion sensor diagnostic unit to determine whether a failure of the combustion sensor exists, based on a sensed value of the combustion sensor when the combustion is not executed, and a characteristic sensor diagnostic unit to determine whether a failure of the characteristic sensor exists, by comparing the mixing ratio estimated by the first estimation unit with the mixing ratio estimated by the second estimation unit when the combustion sensor diagnostic unit determines the combustion sensor is normal.

Methods and systems are provided for a cooling arrangement of an engine. In one example, a method comprises flowing coolant from a high temperature coolant circuit or a low temperature coolant circuit to a fresh air heat exchanger in response to a condensate likelihood.

Methods and systems are provided for a cooling arrangement of an engine. In one example, a method comprises flowing coolant from a high temperature coolant circuit or a low temperature coolant circuit to a fresh air heat exchanger in response to a condensate likelihood.

Various methods and systems are provided for an exhaust gas recirculation system. In one embodiment, an engine method comprises routing exhaust gas from a first cylinder group of an engine to an exhaust gas recirculation passage coupled to both an intake passage and an exhaust passage of the engine, the first cylinder group having a first amount of positive intake and exhaust valve overlap, and routing exhaust gas from a second cylinder group of the engine only to the exhaust passage of the engine, the second cylinder group having a second, smaller amount of positive intake and exhaust valve overlap.

An engine system includes an engine having piston-cylinder arrangements communicating with an intake manifold and an exhaust manifold, a turbocharger including a turbine in communication with the exhaust manifold and a compressor driven by the turbine and in communication with the intake manifold, and an EGR system including an EGR pump having an inlet side in communication with the exhaust manifold and an outlet side in communication with the intake manifold, and an EGR cooler that cools exhaust gas flowing through the EGR system. The engine system also includes a controller operably connected with the EGR pump and configured to selectively operate the EGR pump in a forward mode to flow exhaust gas therethrough in a first direction and in a reverse mode to substantially prevent flow of exhaust gas therethrough or provide a non-exhaust air flow therethrough in a second direction.

An engine system includes an engine having piston-cylinder arrangements communicating with an intake manifold and an exhaust manifold, a turbocharger including a turbine in communication with the exhaust manifold and a compressor driven by the turbine and in communication with the intake manifold, and an EGR system including an EGR pump having an inlet side in communication with the exhaust manifold and an outlet side in communication with the intake manifold, and an EGR cooler that cools exhaust gas flowing through the EGR system. The engine system also includes a controller operably connected with the EGR pump and configured to selectively operate the EGR pump in a forward mode to flow exhaust gas therethrough in a first direction and in a reverse mode to substantially prevent flow of exhaust gas therethrough or provide a non-exhaust air flow therethrough in a second direction.

An internal combustion engine in which a fuel reforming operation in a fuel reformation cylinder is not executed and a warming operation for raising the temperature of the fuel reformation cylinder is executed, when a gas temperature of a fuel reformation chamber at a time point when a piston in the fuel reformation cylinder reaches a compression top dead point is estimated to fall short of a reforming operation allowable lower limit gas temperature. For example, EGR gas is introduced to the fuel reformation chamber without cooling the EGR gas. Further, during a predetermined period from the expansion stroke to an exhaust stroke of an output cylinder, exhaust gas warming fuel is supplied to a combustion chamber. Further, the fuel is combusted in the fuel reformation chamber.

An internal combustion engine in which a fuel reforming operation in a fuel reformation cylinder is not executed and a warming operation for raising the temperature of the fuel reformation cylinder is executed, when a gas temperature of a fuel reformation chamber at a time point when a piston in the fuel reformation cylinder reaches a compression top dead point is estimated to fall short of a reforming operation allowable lower limit gas temperature. For example, EGR gas is introduced to the fuel reformation chamber without cooling the EGR gas. Further, during a predetermined period from the expansion stroke to an exhaust stroke of an output cylinder, exhaust gas warming fuel is supplied to a combustion chamber. Further, the fuel is combusted in the fuel reformation chamber.

Systems, apparatus and methods include control techniques for controlling operation of pre-mixed internal combustion engines in response to a load shedding event. The control techniques determine, in response to the load shedding event, a number of cycles in which to skip combustion of the fuel in the at least one cylinder based on an air-fuel ratio limit in the exhaust flow, prevent combustion of the fuel in the at least one cylinder during the number of skipped cycles, and combust the fuel in the at least one cylinder each time the number of skipped cycles are complete.