Abstract: A vehicle controller adjusts fuel delivered to an engine to compensate for an unknown fuel type being added to a fuel tank in a flexible fueled vehicle. The controller fuels a first set of engine cylinders according to first fueling scheme. For example, the controller fuels the first set assuming that E85 fuel was added to the fuel tank. The controller fuels a second set of engine cylinders according to a second fueling scheme. For example, the controller fuels the second set assuming that E0 fuel was added to the fuel tank. The controller continues to fuel the engine in this manner until an oxygen sensor becomes available. When the oxygen sensor becomes available, the vehicle controller may fuel the engine according to information from the oxygen sensor.

Abstract: A method for checking the accuracy of an oxygen sensor based determination of the alcohol content of the fuel of a flexible fueled vehicle. Following the addition of fuel to the flexible fueled vehicle two alcohol concentration possibilities are calculated. The two alcohol concentration possibilities are then used to calculate thresholds for the determining if the oxygen sensor based determination falls within the thresholds. If the oxygen sensor based determination does not fall within the thresholds then action is taken to counteract an inaccurate determination of alcohol concentration.

Abstract: A method is provided for monitoring the integrity of a fuel composition sensor in a flexible fueled vehicle. At ignition-on, the fuel composition sensor is tested for electrical and rationality viability. After ignition-on, the fuel composition is periodically, non-intrusively, tested for potential rationality errors. Should the non-intrusive testing indicate that a potential error exists, the fuel composition sensor is intrusively tested for rationality errors. If the intrusive test detects that the fuel composition sensor is malfunctioning, the engine control system converts to a limp-in mode and sets the engine operating parameters based on feedback from an exhaust gas oxygen sensor system.

Abstract: The present invention is directed towards a method of controlling combustion parameters of an internal combustion engine prior to oxygen sensor feedback availability for a flexible fueled vehicle. If the vehicle has previously been running on ethanol or has been using ethanol in the recent past, a first strategy is employed which basis engine fueling on the minimum of a theoretically appropriate fueling value and a theoretically calculated value. If the vehicle has not previously been running on ethanol or has not been using ethanol in the recent past, a second strategy is employed which basis engine fueling on the minimum of the theoretically appropriate fueling value, the theoretically calculated value and a roughness calculated value.

Abstract: An apparatus and method are provided for detecting cylinder misfires in an internal combustion engine of a motor vehicle which provides a good signal to noise ratio and is capable of distinguishing from noise related events such as misfire induced bobble and harsh clutching maneuvers. Crankshaft rotation is sensed and crankshaft velocities are measured for each cylinder. Changes in angular velocity are determined and correspond to each of a plurality of cylinder firing events. With a first averaging filter, angular velocity changes are sorted over a predetermined series of cylinder firings and the two middle angular velocity changes are averaged to provide an average change in velocity value. A deviation is determined between the change in angular velocity for a selected cylinder and the average change in velocity.