An exhaust system for a vehicle includes a catalytic converter, an exhaust manifold, an outlet sensor in addition to inlet and outlet pipes. The catalytic converter defines an inlet and an outlet. The exhaust manifold may be operatively configured to couple at least one vehicle combustion chamber to the inlet of the catalytic converter via the inlet pipe. The outlet pipe includes an internal portion and external portion. The outlet pipe may be affixed to the outlet of the catalytic converter. The internal portion of the outlet pipe defines at least one aperture upstream of the outlet sensor.

A method for operating an internal combustion engine having a plurality of cylinders includes: measuring, by exhaust gas sensors arranged at an exhaust gas of every cylinder for which cylinder-specific combustion control is carried out, for each respective cylinder, at least one actual combustion value; comparing each respective measured actual combustion value with a reference combustion value to determine at least one cylinder-specific control deviation for every cylinder for which cylinder-specific combustion control is carried out; determining at least one cylinder-specific control variable for every cylinder for which cylinder-specific combustion control is carried out based on the cylinder-specific control deviation or on every cylinder-specific control deviation; and operating each cylinder for which cylinder-specific combustion control is carried out based on the respective cylinder-specific control variable to bring the respective actual combustion value closer to the respective reference combustion value and minimize the respective control deviation.

A diagnostic system for an internal combustion engine includes an in-cylinder pressure sensor and an ECU. The ECU is configured to: (a) determine whether each cylinder of the evaluation target cylinder group is a lean cylinder; (b) estimate a degree of leanness of the air-fuel ratio of the present lean cylinders when the lean cylinders are present in the evaluation target cylinder group; (c) calculate a polytropic index in an expansion stroke for each cylinder; (d) correlate relationship information for defining a relationship between the polytropic index in the expansion stroke and an air-fuel ratio index value with the polytropic index in the expansion stroke of a reference lean cylinder; and (e) calculate the difference in air-fuel ratio between cylinders on the basis of the polytropic index of the reference lean cylinder, the relationship information correlated with the polytropic index of the reference lean cylinder.

A method for operating an internal combustion engine is described in which a combustion air ratio () is determined and used to determine a deviation of this combustion air ratio from an in particular default or determined set point combustion air ratio. Spontaneous ignition of the internal combustion engine are detected based on the determined deviation () and used to control the operation of the engine.

A system according to the principles of the present disclosure includes an air/fuel ratio determination module and an emission level determination module. The air/fuel ratio determination module determines an air/fuel ratio based on input from an air/fuel ratio sensor positioned downstream from a three-way catalyst that is positioned upstream from a selective catalytic reduction (SCR) catalyst. The emission level determination module selects one of a predetermined value and an input based on the air/fuel ratio. The input is received from a nitrogen oxide sensor positioned downstream from the three-way catalyst. The emission level determination module determines an ammonia level based on the one of the predetermined value and the input received from the nitrogen oxide sensor.

Systems and methods for detecting and compensating miswiring of oxygen sensors of a cylinder bank of an engine are disclosed. In one example, fuel control parameters are monitored to determine whether or not the fuel control parameters diverge to fuel control thresholds. If so, a controller may switch which cylinder's equivalence ratios are adjusted in response to output of a particular oxygen sensor.

A system for controlling operation of an internal combustion engine includes a controller configured to send signals for controlling at least one of air-fuel ratio, spark-ignition timing, and fuel injection timing to an internal combustion engine. The system further includes a sensor configured to send a signal indicative of exhaust gas temperature to the controller. The system is configured to control at least one of the air-fuel ratio, spark-ignition timing, and fuel injection timing based on a signal indicative of at least one of an operating condition of the internal combustion engine and load on the internal combustion engine, and a difference between a target exhaust gas temperature and the signal indicative of the exhaust gas temperature.

A method for torque control of an internal combustion engine includes a pressure sensor that is associated with at least one, but at the most two cylinders of the internal combustion engine, whereby an cylinder internal pressure for the cylinder associated with the pressure sensor is detected. The method carries out an adjustment of injection characteristics for the injectors allocated to the individual cylinders of the internal combustion engine by way of a method which is independent from the detected cylinder pressure. A torque control for the internal combustion engine is performed based on the detected cylinder pressure.

A method for detecting errors in a sensor at a gas cylinder is implemented by a pressure estimation computing device including a processor and a memory device coupled to the processor. The method includes receiving a first pressure measurement from a first sensor associated with a gas cylinder, receiving a design schema describing an intake manifold, the intake manifold included within the gas engine, segmenting the design schema into a plurality of segments, defining a fluid dynamics model associated with each of the plurality of segments, defining a plurality of interconnected 2-port elements based on the plurality of fluid dynamics models, estimating a second pressure measurement for the gas cylinder based on the plurality of interconnected 2-port elements, comparing the first pressure measurement to the second pressure measurement, and determining that the first sensor is in an anomalous state.

A control device for an internal combustion engine includes first and second intake ports (16a, 16b) independent of each other, and first and second fuel injection valves (30a, 30b) provided for the first and second intake ports (16a, 16b), respectively, in each cylinder. Under a situation where an exhaust variable valve mechanism (38) is controlled such that a first exhaust valve (32a) is opened earlier than a second exhaust valve (32b), first and second air-fuel ratios A/F1, A/F2 are respectively obtained in a first half and a second half of an exhaust stroke. When the obtained first air-fuel ratio A/F1 (or the second air-fuel ratio A/F2) is lean, a fuel injection amount in a next cycle by the first or second fuel injection valve (30a, 30b) corresponding to the first air-fuel ratio A/F1 (or the second air-fuel ratio A/F2) that is lean is reduced.