Methods and systems are provided for pinpointing a source of degradation in a vehicle engine system. In one example, a method includes spinning an engine of a vehicle unfueled in a forward and a reverse direction, in no particular order, and recording a first intake air flow and a second intake air flow, respectively, in an intake of the engine, and where the source of degradation is indicated as a function of both the first air flow and the second air flow. In this way, the degradation of the vehicle engine system may be pinpointed as to being located in the intake manifold, the exhaust system, or the engine.

An engine system includes an internal combustion engine, an electrical power system configured to provide electrical power in the engine system, and an electrified air system powered by the electrical power system to selectively increase a flow of intake air and exhaust gas to the engine. The electrified air system further includes an EGR pump operable to recirculate a portion of exhaust gas output from the engine and an electric turbocharger including a turbine, a compressor driven by the turbine via a shaft coupled therebetween, and an electrical machine coupled to the shaft. The electrical machine is configured to operate in a motoring mode to drive the shaft and cause the compressor to output boosted intake air to the engine and operate in a generating mode to transform rotational power from the shaft into electrical power that is provided back into the electrical power system.

One embodiment is a system comprising an engine including a dedicated EGR cylinder configured to provide EGR to the engine via an EGR loop, a non-dedicated cylinder, a plurality of injectors, an ignition system including a plurality of spark plugs, an intake throttle, and an electronic control system. The electronic control system is configured to control combustion during transient operation of the engine by determining one or more combustion control parameters compensating for variation of one or more of inert matter, unburned air and unburned fuel in EGR output by the dedicated EGR cylinder during transient operation of the engine, and an effect of the EGR loop on inert matter, unburned air and unburned fuel provided to the plurality of cylinders, and controlling operation of at least one of the throttle, the ignition system and the plurality of injectors in response to at least one of the one or more combustion control parameters.

Methods and systems are provided for adjusting a location of a fuel injection in response to a substitution rate and a desired EGR flow. In one example, a method may include injecting a first fuel to a combustion chamber via a direct injector positioned to inject directly into the combustion chamber, injecting a second, different, fuel to the combustion chamber via an exhaust port injector positioned to inject toward an exhaust valve of the combustion chamber, and combusting the first and second fuels together in the combustion chamber.

Provided is a control device and a control method of a high-efficiency internal combustion engine capable of stabilizing combustion and suppressing NO.sub.x emissions without unnecessarily increasing a mounting load on an ECU. Therefore, the control device of the internal combustion engine for controlling the internal combustion engine includes an ignition plug that ignites an air-fuel mixture of fuel and air in the combustion chamber, a combustion pressure estimation sensor that detects a combustion pressure in the combustion chamber, and a crank angle sensor that detects a crank angle of a crankshaft. An MBT region is set based on an ignition delay period from an ignition timing of the ignition plug calculated from a detection value of the combustion pressure estimation sensor and a detection value of the crank angle sensor to a combustion start timing in the combustion chamber, and a combustion period from the combustion start timing to a set amount combustion end timing when a set amount of combustion ends. An ignition timing of the ignition plug is controlled so as to fall within the set MBT region.

An embodiment device includes an auxiliary brake including a retarder selectively operated to consume an output of a transmission to generate a braking force and an engine brake selectively operated to increase a flow resistance of an exhaust gas discharged from an engine to generate a braking force, a gas flow volume controller configured to open or close flow paths of an engine intake line and an engine exhaust line, and a controller configured to compare a first braking force difference with a predetermined reference braking force when the auxiliary brake is operated during coasting traveling and to determine and control an opening rate of the gas flow volume controller based on the first braking force difference and an engine speed when the first braking force difference is less than the reference braking force.

In one aspect, a method for controlling an internal combustion engine system including an exhaust gas recirculation (EGR) valve and a variable-geometry turbocharger (VGT) having a compressor and a turbine includes receiving a plurality of requests for the internal combustion engine system. The method also includes predicting a plurality of expected states of the internal combustion engine system based on the plurality of requests and generating sets of candidate control points for actuating the EGR valve and the VGT based on the plurality of expected states. The method further includes selecting a set of candidate control points that avoids a surge condition of the compressor and based on the selected set of candidate control points, generating commands for actuating the EGR valve and the VGT.

Various methods and systems are provided for controlling emissions and a likelihood of engine knock during combustion in a multi-fuel engine. A method for an engine includes mixing an amount of a first fuel and an amount of a second fuel to combust a fuel mixture having a fuel ratio of the first fuel relative to the second fuel, the first fuel having a faster combustion flame speed relative to the second fuel, the fuel mixture having an air-to-fuel ratio with an amount of air delivered to the engine. The method further includes controlling either or both of a speed of combustion and a stability of combustion of the fuel mixture with the amount of air delivered to the engine by changing at least one of the fuel ratio, the air-to-fuel ratio, or both of the fuel ratio and the air-to-fuel ratio.

To provide a controller and a control method for internal combustion engine which can set appropriately an angle interval for estimating the combustion state in accordance with change of a burning angle interval, and can reduce calculation processing load for estimation of the combustion state. A controller for internal combustion engine changes the estimation crank angle interval based on an operating condition of the internal combustion engine; calculates an increment of gas pressure torque by burning at each crank angle of the estimation crank angle interval; and estimates the combustion state of the internal combustion engine, based on the increment of gas pressure torque by burning in the estimation crank angle interval.

Methods and systems are provided for adjusting a substitution ratio based on water in a combustion mixture of a multi-fuel engine. In one example, a method includes adjusting a substitution ratio in response to an amount of water provided to a multi-fuel engine configured to combust a first fuel and a second fuel, the second fuel different than the first fuel.