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 the performance of a refueling event detection system for a vehicle is provided. The method includes the steps of a) determining a fuel change amount based on a difference of an indicated fuel amount and a previously indicated fuel amount, b) determining a consumed amount of fuel consumed by the engine since a prior refueling event was detected, and c) diagnosing the performance of the refueling event detection system based on the consumed amount and the fuel change amount.

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 the performance of a refueling event detection system for a vehicle is provided. The method includes the steps of a) determining a fuel change amount based on a difference of an indicated fuel amount and a previously indicated fuel amount, b) determining a consumed amount of fuel consumed by the engine since a prior refueling event was detected, and c) diagnosing the performance of the refueling event detection system based on the consumed amount and the fuel change amount.

Abstract: An engine control module and method configured to correct an engine crank sensor signal for errors in an apparent location of a tooth edge on a crank wheel is provided. A correction factor is determined based on a first formula if a comparison of adjacent pulse intervals to predetermined thresholds indicates that a tooth edge appears to be abnormally late, and determined based on a second formula if a comparison of adjacent pulse intervals to other predetermined thresholds indicates that a tooth edge appears to be abnormally The correction factor is set to a null value if the correction factor is not determined based on the first formula or the second formula; and operating an engine based on the correction factor.

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.

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.

Abstract: A method for detecting an engine block heater includes block heater detection logic and a data table containing calibration thresholds. The method determines a time-series of delta (?) engine coolant temperatures (ECT), which represent the respective differences between a start-up ECT and a plurality of operating ECT values measured thereafter. The method integrates the time-series to obtain a ? ECT integral. The method also maintains an integrated engine speed parameter accumulated over the course of the detection period. Throughout the detection period, the method retrieves a threshold value from the table based on the integrated engine speed (Y-axis) versus an elapsed time (X-axis) since the detection period began. When the calculated ? ECT integral value exceeds the retrieved threshold, the method determines that the block heater was operated, which can thereafter be used to suppress sensor rationality testing or reporting of results thereof.

Abstract: An apparatus and method for diagnosing an airflow control system of an internal combustion engine, the method comprising: determining if a valve is in a stable position; commanding the valve of the airflow control system to move from a first position to a second position; determining a period of time for the valve to move from the first position to the second position; providing a first signal if the period of time is greater than or less than a predetermined period of time, the predetermined period of time corresponding to an amount of time necessary to move the valve from the first position to the second position under predetermined conditions; and providing a second signal if the period of time is within a range defined by the predetermined period of time.

Abstract: A method for detecting an engine block heater includes block heater detection logic and a data table containing calibration thresholds. The method determines a time-series of delta (?) engine coolant temperatures (ECT), which represent the respective differences between a start-up ECT and a plurality of operating ECT values measured thereafter. The method integrates the time-series to obtain a ? ECT integral. The method also maintains an integrated engine speed parameter accumulated over the course of the detection period. Throughout the detection period, the method retrieves a threshold value from the table based on the integrated engine speed (Y-axis) versus an elapsed time (X-axis) since the detection period began. When the calculated ? ECT integral value exceeds the retrieved threshold, the method determines that the block heater was operated, which can thereafter be used to suppress sensor rationality testing or reporting of results thereof.

Abstract: An automotive system has a primary control module, such as an engine control module (ECM) configured for connection to a malfunction indicator lamp (MIL), and a secondary control module, such as a transmission control module (TCM), each in communication with each other over a bus. Each control module includes a respective diagnostic data status record. Each record includes a pending fault field, a confirmed fault field and an MIL control status field. An improved method for synchronizing the diagnostic data contained in the respective status records includes an extended status signal set that is used to communicate over the bus. The set includes a diagnostic testing complete signal, a fault present signal and a MIL request signal indicative of a request to illuminate the MIL. Logic in the receiving control module (ECM) interprets the extended status signal set to properly synchronize its diagnostic data status record with the TCM's, including both pending and confirmed faults.

Abstract: An apparatus and method for diagnosing an airflow control system of an internal combustion engine, the method comprising: determining if a valve is in a stable position; commanding the valve of the airflow control system to move from a first position to a second position; determining a period of time for the valve to move from the first position to the second position; providing a first signal if the period of time is greater than or less than a predetermined period of time, the predetermined period of time corresponding to an amount of time necessary to move the valve from the first position to the second position under predetermined conditions; and providing a second signal if the period of time is within a range defined by the predetermined period of time.

Abstract: A system and method for evaluating the integrity of a leak detection test for a purge valve of a fuel system in a vehicle reduces or eliminates false failures. The method is executed on an engine control module (ECM) and is configured to determine when vehicle soak conditions meet first criteria conducive to fuel vapor condensation in the fuel tank. The first criteria include a predetermined temperature drop in ambient air temperature between successive drive cycles. The ECM is further configured to determine when a vehicle maneuver meets second criteria indicative of the capability of the maneuver to initiate fuel slosh in the fuel tank, to thereby establish a trigger event. The ECM is further configured to determine, after the trigger event, the maximum slope of a fuel tank vacuum increase. The ECM is still further configured to produce a slope ratio as a function of the maximum vacuum increase slope and a reference vacuum slope corresponding to a slope that is unaffected by any slosh/condensation events.

Abstract: In a multi-cylinder internal combustion engine having intake valve deactivation apparatus providing de-activation of the intake valves of selected cylinders during engine operation, correct cylinder activation status is verified by measuring gas pressure in a conduit conducting combustion related gases through the cylinders of the engine, detecting consecutive pulses in the pressure due to predetermined activations of the intake valves, comparing the time periods between the consecutive pulses to reference time periods based on crankshaft position and corresponding to expected time periods between the consecutive pulses and providing verification signals and cylinder identification of faulty intake valve deactivation or activation in response to the comparisons.

Abstract: Low range limiting malfunctions of an engine coolant temperature (ECT) sensor are diagnosed by comparing a change in the sensed temperature during engine operation with a calibrated temperature change. If the change in sensed temperature fails to exceed the calibrated temperature change, and a diagnostic for detecting a stuck ECT signal is either inconclusive or passed, a low range limiting malfunction of the sensor is indicated. If the diagnostic for detecting a stuck ECT signal is failed, the low range limiting diagnostic concludes with no report even if the change in sensed temperature fails to exceed the calibrated temperature change.

Abstract: The rationality of a measured temperature of transmission fluid is assessed by comparing it to an engine coolant temperature. The rationality assessment is enabled when the ambient air temperature is reliably determined and deemed normal, a sufficient soak condition is confirmed, and the measured temperature, the engine temperature and the ambient air temperature are all within prescribed ranges. The rationality assessment monitors the ambient temperature relative to the initial engine temperature during the assessment period, and the assessment is disabled if the ambient air temperature deviates from the initial engine temperature by more than a calibrated value.

Abstract: A control system and method to monitor an intake air temperature sensing circuit for an internal combustion engine is shown. The electronic controller is connected to the intake air temperature sensing circuit, coolant temperature sensor, and a plurality of other engine sensors. The controller determines whether the measured intake air temperature changes in response to a change in actual intake air temperature, based upon the engine operating conditions and the measured intake air temperature. The controller determines whether the measured intake air temperature is representative of actual intake air temperature, based upon the measured intake air temperature, the coolant temperature, and at least one engine operating condition. The invention is an element of an on-board diagnostic system, typically related to vehicle emissions.

Abstract: A default value of transmission input speed in a motor vehicle powertrain having an automatic-shift multi-gear ratio power transmission is continuously updated based on a measured value of the input speed and other reliable speed data including transmission output speed and engine speed. The default value is substituted for the measured input speed when a malfunction of the input speed sensor is detected, and transitions back to the measured input speed when the input speed sensor malfunction is no longer present.

Abstract: A default value of transmission output speed in a motor vehicle powertrain having an automatic-shift multi-gear ratio power transmission is continuously updated based on a measured value of the output speed and other reliable speed data including transmission input speed and vehicle speed. The default value is substituted for the measured output speed when a malfunction of the output speed sensor is detected, and transitions back to the measured output speed when the output speed sensor malfunction is no longer present.