Abstract: A method of operating an engine in a vehicle equipped with an evaporative emissions system is described. The engine is configured to perform automatically an engine stop and an engine restart when the vehicle stops moving to increase fuel economy of the vehicle. The method includes the steps of determining if an engine stop is allowed while a diagnostic test of the of the evaporative emissions system is being performed if an engine stop is requested, and preventing the engine stop if the engine stop is not allowed.

Abstract: A method for monitoring an evaporative emissions control (EVAP) system that includes compensating a diagnostic leakage test based on a fuel consumption amount during a test interval is disclosed. The method includes establishing a leak test pressure in the EVAP system, operating the operating the associated valves and pumps such that the EVAP system is expected to be isolated, determining an actual pressure change of the EVAP system, determining an expected pressure change of the EVAP system based on vehicle operating conditions that include the fuel consumption amount, and indicating that a leak is detected if the actual pressure change differs from the expected pressure change by more than a difference threshold.

Abstract: A method for diagnosing a component failure in a saddle-type fuel tank assembly is provided. The method includes a) updating a maximum amount to a subsequent amount of fuel if the subsequent amount of fuel is greater than the maximum amount, b) updating a minimum amount to the subsequent amount of fuel if the subsequent amount of fuel is less than the minimum amount, c) determining a fuel consumption amount, and d) determining that one or more of a first fuel level sender and a second fuel level sender have failed if the difference between the maximum amount and minimum amount is less than a first threshold, and the fuel consumption amount is greater than a second threshold.

Abstract: A method of operating an engine in a vehicle equipped with an evaporative emissions system is described. The engine is configured to perform automatically an engine stop and an engine restart when the vehicle stops moving to increase fuel economy of the vehicle. The method includes the steps of determining if an engine stop is allowed while a diagnostic test of the of the evaporative emissions system is being performed if an engine stop is requested, and preventing the engine stop if the engine stop is not allowed.

Abstract: A method for diagnosing a component failure in a saddle-type fuel tank assembly is provided. The method includes a) updating a maximum amount to a subsequent amount of fuel if the subsequent amount of fuel is greater than the maximum amount, b) updating a minimum amount to the subsequent amount of fuel if the subsequent amount of fuel is less than the minimum amount, c) determining a fuel consumption amount, and d) determining that one or more of a first fuel level sender and a second fuel level sender have failed if the difference between the maximum amount and minimum amount is less than a first threshold, and the fuel consumption amount is greater than a second threshold.

Abstract: A method to determine a performance characteristic of an exhaust system of an engine, where the exhaust system includes an exhaust gas sensor that outputs an exhaust gas signal. A combustion event in a cylinder is fueled at an air-fuel ratio selected to produce exhaust gas that is expected to be distinguishable by the exhaust gas sensor from exhaust gas produced by other combustion events, and used to determine the performance characteristic. The performance characteristic may be an exhaust gas transport time of the exhaust system, a sensitivity characteristic of the exhaust gas sensor, or a fueling correction value necessary to restore fueling to, for example, stoichiometry. Such a method is useful to detect physical changes in the exhaust system such as relocating the exhaust gas sensor, or detect if the exhaust gas sensor is damaged or not operating properly.