Abstract: A system and method for controlling an internal combustion engine determine a catalyst gain based on an exhaust gas sensor positioned upstream relative to a catalyst and at least one exhaust gas sensor positioned downstream relative to at least a portion of the catalyst and use the gain to determine the condition or performance of the catalyst. The gain may be determined by modeling the catalyst as an integrator with an unknown gain and estimating the gain using a polynomial approximation. The gain is compared to an expected value or threshold associated with current operating conditions, such as catalyst temperature and/or mass air flow.

Abstract: An engine diagnostic system for use with an internal combustion engine coupled to a lean NOx trap with a sensor coupled downstream of the trap. The sensor provides two output signals, one indicative of an air-fuel ratio and the second indicative of a NOx concentration. Construction of the sensor insists that proper indication of NOx concentration is dependent upon proper operation of the first output signal. Degradation of the NOx concentration signal is determined when the first output signal has degraded.

Abstract: A control system 14 for a bi-fuel engine 12 is provided. The control system 14 includes a powertrain controller 52 and a bi-fuel controller 54. The controller 52 has a set of fuel injector drivers 92. The controller 50 has a set of gasoline fuel injector drivers 104 and a set of alternate fuel (AF) fuel injector drivers 106. Each of drivers 92 in controller 52 is electrically connected to a driver 104 and a driver 106 in controller 50. Thus, a control signal generated by a single driver 92 can be utilized by either of drivers 104, 106 to generate a corresponding control signal for controlling a gasoline fuel injector 38 or a AF fuel injector 40, respectively.

Abstract: The air flow into an engine is estimated via a speed-density calculation wherein the volumetric efficiency is estimated on-line. There are three interconnected observers in the estimation scheme. The first observer estimates the flow through the throttle based on the signal from a mass air flow sensor (MAF). The second observer estimates the intake manifold pressure using the ideal gas law and the signal from a intake manifold absolute pressure sensor (MAP). The third observer estimates the volumetric efficiency and provides an estimate of the air flow into the engine.

Abstract: A system and a method for operating an internal combustion engine at a six-stroke, eight-stroke, or greater number of strokes cycle is disclosed. The combustion of the fuel and air is accomplished in two combustion steps with at least one expansion and compression process in between the two combustions, with the second combustion occurring at a stoichiometric air-fuel ratio. The first combustion at lean air-fuel ratio provides high efficiency. The products of the first combustion are subjected to a second combustion event at stoichiometric air-fuel ratio. Consequently, high conversion efficiency of nitrogen oxides in the exhaust aftertreatment device, available at stoichiometric conditions, can be achieved.

Abstract: A system and a method for controlling engine torque in an internal combustion with a randomly operable intake valve and a selectable intake valve is disclosed in which torque is controlled via a throttle valve when the randomly operable intake valve is deactivated and via intake valve closing time of the randomly operable intake valve when the selectable intake valve is deactivated.

Abstract: Purging of a NOX trap is initiated if the estimated mass of NOX in the trap exceeds a NOX mass threshold value unless the estimated probability that the engine will be subjected to high load and high speed conditions exceed a probability threshold value, in which event the decision whether to initiate the purging of said trap is delayed for a predetermined time interval.

Abstract: A method of controlling the air-fuel ratio of an internal combustion engine having an exhaust passage including a catalytic converter. The method includes providing a first air-fuel ratio sensor upstream of the catalytic converter, and providing a second air-fuel ratio sensor downstream of the catalytic converter. A control module having an input connected to the first and second air-fuel ratio sensors and an output connected to actuators for controlling the engine is also provided. This establishes a first feedback loop including the first air-fuel ratio sensor and a second feedback loop including the second air-fuel ratio sensor. The method further includes detecting an output value of the second air-fuel ratio indicative of a rich or lean exhaust gas air-fuel ratio. In response to the output value, the system monitors the engine mass airflow, and controls the duration of air-fuel ratio of the engine as a function of the engine mass airflow.

Abstract: An electronic engine controller (EEC) for an internal combustion engine develops an estimate of air charge by receiving a signal from an air meter positioned in an intake manifold of the engine. The signal is indicative of mass flow rate of air past the meter. In one embodiment EEC develops an air charge estimate by developing a first pressure value which is indicative of the pressure in the intake manifold. A pressure correction term is then generated and added to the first pressure value to generate an improved estimate, which takes the dynamic response of the air meter into account, of pressure in the intake manifold. The air charge estimate is then developed from the pressure estimate. In another embodiment, a first mass value, which is indicative of the mass of air in the intake manifold is developed. A mass correction term is then generated and added to the first mass value to generate the improved estimate.