Methods and systems using model based and iterative calculations of mass flow throughout an internal combustion engine system. A secondary air injection valve is provided to selectively allow intake air to pass to the exhaust side of the engine system to aid in exothermic reaction with exhaust gasses exiting the engine for various purposes. The iterative calculations of mass flow include estimation of the mass flow through the secondary air injection valve.

A method detects a fault, in particular coking, in the intake tract of an internal combustion engine with direct fuel injection, a throttle valve, and a variable intake valve lift controller. The method has the steps of a) carrying out a first quantity deviation test, by which a first air ratio value is ascertained that is formed from a lambda value, which is measured during the first quantity deviation test, and a desired lambda value of the fuel combustion in the fuel chambers of the internal combustion engine, wherein in the first quantity deviation test, a load control is carried out by the variable intake valve lift controller; b) carrying out a second quantity deviation test, by which a second air ratio value is ascertained that is formed from a lambda value, which is measured during the second quantity deviation test, and a desired lambda value of the fuel combustion in the fuel chambers of the internal combustion engine, wherein in the second quantity deviation test, a load control is carried out by the throttle valve; and lastly c) determining a comparison result from the first air ratio value and the second air ratio value, the presence of a fault in the intake tract of the internal combustion engine being detectable using the comparison result.

Systems and methods for controlling a gasoline urea selective catalytic reductant catalyst are described. In one example, an observer is provided that corrects an estimate of an amount of NH.sub.3 that is stored in a SCR. The amount of NH.sub.3 that is stored in the SCR is a basis for generating additional NH.sub.3 or ceasing generation of NH.sub.3.

A method includes: determining that at least one cylinder of a first cylinder bank of an engine is active; determining that at least one cylinder of a second cylinder bank of the engine is inactive; receiving an inlet temperature of a selective catalytic reduction system; comparing the inlet temperature to a temperature setpoint; and adjusting at least one of a first exhaust manifold pressure setpoint for the first cylinder bank or a second exhaust manifold pressure setpoint for the second cylinder bank based on the comparison.

A neat-fuel direct-injected compression ignition engine having a thermal barrier coated combustion chamber, an injection port injects fuel that satisfies a stoichiometric condition with respect to the intake air, a mechanical exhaust regenerator transfers energy from exhaust gas to intake compression stages, an exhaust O.sub.2 sensor inputs to a feedback control to deliver quantified fuel, a variable valve actuation (VVA) controls valve positions, an exhaust gas temperature sensor controls exhaust feedback by closing the exhaust valve early according to the VVA, or recirculated to the chamber with an exhaust-gas-recirculation (EGR), heat exchanger, and flow path connecting an air intake, a load command input, and a computer operates the EGR from sensors to input exhaust gas according exhaust temperature signals and changes VVA timing, the load control is by chamber exhaust gas, the computer operates a fuel injector to deliver fuel independent of exhaust gas by the O.sub.2 signals.

Disclosed is a throttle quadrant arrangement utilizing a throttle lever mechanically connected to three Rotary Variable Differential Transformers (RVDTs). The signals from the RVDTs are monitored by a process where the processing component. More specifically, RVDT outputs are monitored by the engine control system to determine if they are outside a predetermined range of operability. If an RVDT is not operable, the engine control system establishes a thrust output using the signal from one of the functional two. If only one or none are within the range, the system moves on to a default mode.

A method and system is provided for correcting fueling commands. For example, the method and system may calibrate an engine operating in a steady-state mode by determining a plurality of accuracy errors associated with a fueling rate based on a plurality of sensor measurements. The method and system may determine fueling rate correction data during on-line operation of the engine based on the plurality of accuracy errors. The on-line operation of the engine may comprise operating the engine in a transient mode at a first period of time and a steady-state mode at a second period of time. The method and system may control at least one fueling valve during operation of the engine using a corrected fueling command. The corrected fueling command is based on the fueling rate correction data.

The invention relates to controlling engine braking of an internal combustion engine wherein the method includes setting the engine in an engine braking mode comprising i) interrupting fuel supply to a first cylinder, ii) restricting the flow of gas through an exhaust duct using an adjustable flow restricting member, and iii) controlling inlet and exhaust valves of the first cylinder in a compression-release mode comprising controlling the valves to compress gas in a combustion chamber when the piston moves towards the top dead center position (TDC) and release compressed gas into the exhaust duct when the piston is near the TDC. The method includes, prior to ii and iii: reducing a total gas mass flow rate through the engine by controlling, for at least one of valve, reducing a valve lift and/or adjusting a timing of a valve opening or closing so as to reduce the gas mass flow rate through the cylinder.

A system and method for dynamically deactivating engine cylinders of an engine equipped with a cylinder deactivation system, where the system and method control torsional vibration in the engine while deactivating cylinders using a computer programed with a desired firing density and a controlled range of engine vibration frequencies. The computer dynamically determines a cylinder firing pattern that provides the desired firing density while optimizing a cost function norm in the controlled range of engine vibration frequencies. The cylinder deactivation system in the engine is then controlled using the determined cylinder firing pattern.

A method for the model-based open-loop and closed-loop control of an internal combustion engine includes the steps of: during stationary operation, switching takes place cyclically from the normal operation to an exploration operation, wherein in the exploration operation, an exploration measure of quality (J/EXP) is calculated in accordance with combustion model and variance (VAR) thereof, wherein the exploration measure of quality (J/EXP) is set as essential for the operating point of the internal combustion engine, wherein on the basis of the operating variables of the internal combustion engine combustion model is adapted, and wherein switching back to normal operation takes place.