Methods and systems are provided for detection of cylinder-to-cylinder air fuel ratio imbalance in engine cylinders. In one example, a method may include indicating air fuel ratio imbalance in an engine cylinder based on a comparison of an estimated cylinder acceleration for the cylinder and a calibrated cylinder acceleration for each of the engine cylinders. The indication of imbalance may be further confirmed based on one or more of an exhaust air-fuel ratio, an exhaust manifold pressure, and an individual cylinder torque weighted by respective confidence factors.

A method for controlling a filling of an exhaust-gas component storage-device of a catalytic-converter in the exhaust-gas of an internal-combustion-engine, in which an actual fill level (.sub.mod) of the exhaust-gas component storage-device is ascertained using a first-system model to which signals (.sub.in,meas) of a first-exhaust-gas probe that extends into the exhaust-gas flow upstream from the catalytic-converter and that acquires a concentration of the exhaust-gas component are supplied, if this first exhaust-gas probe is ready for operation. A lambda-target-value (.sub.in,set) for a first control-loop is specified by a lambda-target-value pilot control, and that, if the first exhaust-gas probe is not ready for operation, a replacement signal for the signal of the first exhaust-gas probe is supplied to the system-model, and the replacement signal is used in the lambda-target-value pilot control as an initial-value for the lambda-target-value. Also described is a control device for the method.

A system and method is provided for the use of the ion current signal characteristics for onboard cycle-by-cycle, cylinder-by-cylinder measurement. The system may also control the engine operating parameters based on a predicted NOx emission level, CO emission level, CO.sub.2 emission level, O.sub.2 emission level, unburned hydrocarbon (HC) emission level, cylinder pressure, or a cylinder temperature measurement according to characteristics of the ion current signal.

An oxygen concentration-based exhaust gas recirculation (EGR) flow rate compensation control method may include a model compensation mode, which confirms engine information acquired from an engine system, calculates an intake oxygen concentration by a model intake oxygen mass ratio through a combination of an intake oxygen mass ratio model value and a model exhaust lambda value and an indirect intake oxygen mass ratio through a combination of the intake oxygen mass ratio model value and an exhaust-side measurement lambda value, respectively, and compensates the model intake oxygen mass ratio as a model intake oxygen mass ratio compensation value applying a compensation error relative to the indirect intake oxygen mass ratio by using the model intake oxygen mass ratio as a model intake oxygen mass ratio current value, by a controller.

In some examples, a system including one or more processors may receive sensor data from one or more sensors indicating one or more engine parameters of an engine including a combustion chamber. Based on the sensor data, the system may determine a homogeneity index indicative of a homogeneity of an air-fuel mixture within the combustion chamber. Furthermore, the system may determine an estimated amount of NOx in the exhaust gas based at least in part on the homogeneity index. In addition, based at least partially on the estimated amount of NOx in the exhaust gas, the system may send an instruction to control an engine component.

A means of detecting the in-situ fuel-to-air-ratio (FAR) in a combustor or flame zone using a Fourier-based flame ionization probe is presented. The use of multiple excitation frequencies and its detection at certain frequencies or combinations of harmonics of those excitation frequencies, namely, the inter-modulation distortion, provides a novel means of extracting a high signal-to-noise ratio (SNR) FAR measurement in a combustor.

A controller of an internal combustion engine includes a sensor, a control unit controlling the engine, and a detector obtaining detection data from the sensor and transmitting the data to the control unit. The detector includes a detection data obtainer obtaining the detection data and storing the detection data in a storage upon having an input of a trigger signal, and a detection data transmitter transmitting the detection data stored in the storage to the control unit, and the control unit includes a trigger output unit outputting the trigger signal at a certain rotation angle timing of the internal combustion engine, and a detection data receiver obtaining the detection data from the detector.

A control system for an engine includes one or more processors configured to determine when a change in one or more of oxygen or fuel supplied to an engine. The one or more processors also are configured to, responsive to determining the change in oxygen and/or fuel supplied to an engine, direct one or more fuel injectors of the engine to begin injecting fuel into one or more cylinders of the engine during both a first fuel injection and a second fuel injection during each cycle of a multi-stroke engine cycle of the one or more cylinders.

The present invention provides a catalyst diagnosis device that enables precisely grasping a variation of AFR and diagnosing a deteriorated condition of the catalyst based on the variation. A timer counts elapsed time Tosc until downstream AFU (AFRd) meets a predetermined threshold condition when the fuel injection quantity is corrected by increasing or decreasing it so that as to the AFRu, the transition from either of leanness or richness to the other is repeated with the stoichiometric area between the leanness and the richness. An OSA calculating section calculates an Oxygen Storage Amount (OSA) as a function of the AFR, Mfuel, Ne and Tosa. An OPA calculating section calculates an Oxygen Purge Amount (OPA) as a function of the AFR, Mfuel, Ne and Topa. A deterioration diagnosing section diagnoses a deteriorated condition of the catalyst C on the basis of at least one of the OSA and OPA.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, an amount of opening overlap between a plurality of intake valves and a first set of exhaust valves coupled to the first exhaust manifold may be adjusted responsive to a transition from an estimated combustion air-fuel content to a leaner air-fuel content of the blowthrough air on a cylinder to cylinder basis. As one example, the transition may be determined from an output of an oxygen sensor positioned within the first exhaust manifold or an exhaust runner of each of the first set of exhaust valves.