Abstract: A diagnostic method for a motor vehicle having an internal combustion engine operable in a plurality of compression ratio operating states includes the steps of determining a change in spark adjustment required to avoid knock as the engine is operated in selected ones of the compression ratio operating states, and evaluating operation of the internal combustion engine based at least in part on the change in spark adjustment.

Abstract: A diagnostic method for a motor vehicle having an internal combustion engine operable in a plurality of compression ratio operating states includes the steps of determining a change in idle air flow of the engine as the engine is operated in selected ones of the compression ratio operating states, and evaluating operation of the internal combustion engine based at least in part on the change in idle air flow.

Abstract: An internal combustion engine having electronic throttle control includes an air assisted injector system for directing a controlled amount of air directly to the combustion chamber without passing through the throttle body. A method of diagnosing faults in the air assisted injector system is disclosed. The method comprises the steps of measuring the airflow entering an intake of the electronic throttle of the engine at idle speed with the air assisted injector system operating at a first rate of airflow, turning the air assisted injector system off, measuring the airflow entering the intake of the electronic throttle of the engine at idle speed with the air assisted injector system off, and generating an error signal as a function of the two measured values.

Abstract: A method of operating a variable compression internal combustion engine in a motor vehicle includes the steps of determining a driveline surge based at least in part on operating parameters of the motor vehicle, determining a driveline surge tolerance based at least in part on one or more of the vehicle operating parameters, and selecting one of the compression ratio operating modes based at least in part on a comparison of the driveline surge to the driveline surge tolerance. With a variable compression engine operating in a high compression ratio mode or a low compression ratio mode, the low compression ratio mode is selected if the driveline surge exceeds the driveline surge tolerance. Otherwise, if the driveline surge is less than or equal to the driveline surge, then the high compression ratio mode is selected.

Abstract: A method is described for limiting a change in torque transmitted through a vehicle powertrain when in a predetermined range. Such a method minimizes transmission gear separation, or “clunk”. In one approach, the rate cf change of powertrain output is limited when powertrain output is near zero transmitted torque. The limitation is not used under other circumstances so as not to hinder driver performance.

Abstract: Optimum MBT and BDL ignition timing value are obtained from calibration values stored in stability limited (SL) and optimum power (OP) calibration tables using a power index (PI) value that is indicative of the relative desire of the driver for fuel economy or power to interpolate over the range of values in the SL and OP tables to calculate values of MBT and BDL that are optimal for all altitudes and levels of driver demand. The ignition timing value used at any point in time is preferably the lesser of the MBT value and the BDL value. The calibration values for MBT and BDL ignition timing are associated with cam timing values in cam timing tables so that ignition timing changes in lock step with the cam timing.

Abstract: A method for controlling a powertrain of a vehicle adjusts a minimum allowed airflow based on operating conditions. Specifically, when conditions of engine speed and/or vehicle speed area away from idle conditions, no increasing of the minimum allowed airflow is carried out. However, when conditions of engine speed and/or vehicle speed area approaching idle conditions, the minimum allowed airflow is increased to the required airflow for those idle conditions.

Abstract: A vehicle control system is described for controlling a torque converter coupled to an engine. The controller engages the torque converter before negative powertrain output becomes less than a predetermined value. Such an approach allows for torque converter locking in the negative powertrain output region. Such an approach is especially suited to vehicles having certain torque converters, which are difficult to lock at large negative torque values.

Abstract: A method and apparatus for operating a lean-burn internal combustion engine in cooperation with an exhaust gas purification system having a three-way catalyst and a NOx trap located downstream of the three-way catalyst includes a controller which calculates current levels of tailpipe NOx during lean engine operating conditions based upon the difference between a determined instantaneous feedgas NOx concentration and a determined instantaneous trap efficiency. The controller discontinues lean engine operation when the tailpipe NOx, expressed in terms of either grams-per-mile or grams-per-hour, exceeds a predetermined threshold level, either instantaneously or as averaged over the course of a trap purge-fill cycle.

Abstract: A method and system for controlling the operation of an internal combustion engine, wherein exhaust gas generated by the engine is directed through an emission control device, includes determining instantaneous rates of storage for a constituent of the exhaust gas, such as NOx, as well as the capacity reduction of the device to store the exhaust gas constituent as a function of a calculated value representing an amount of SOx which has accumulated in the device since a prior device-regeneration (desulfation) event. The calculated accumulated SOx value is also preferably used to schedule a device-regeneration event, as when the calculated accumulated SOx value exceeds a predetermined threshold value.

Abstract: A method and system for controlling the operation of an internal combustion engine, wherein exhaust gas generated by the engine is directed through an emission control device, includes determining instantaneous rates of storage for a constituent of the exhaust gas, such as NOx, as well as the capacity reduction of the device to store the exhaust gas constituent as a function of a calculated value representing an amount of SOx which has accumulated in the device since a prior device-regeneration (desulfation) event. The calculated accumulated SOx value is also preferably used to schedule a device-regeneration event, as when the calculated accumulated SOx value exceeds a predetermined threshold value.

Abstract: A method and system for diagnosing catalyst operation in an internal combustion engine having a two-bank, three EGO sensor structure includes monitoring when the EGO sensors switch states between rich and lean and determining the ratio between a switch count of the post-catalyst EGO sensor signal and a switch count of a pre-catalyst EGO sensor signal over a selected time period. If the exhaust bank is a one-sensor bank having only a post-catalyst EGO sensor and not a pre-catalyst EGO sensor, the system uses the switch count from the pre-catalyst EGO sensor in the two-sensor bank to calculate the switch ratio, thereby allowing calculation of two switch ratios without two matched pairs of EGO sensors. The switch ratio indicates the efficiency of the catalyst and may be compared with later-generated ratios to monitor converter efficiency over time.

Abstract: A method for controlling an engine coupled to a transmission is described. The method is especially suited for a transmission having at least one gear in which an over-running clutch is present. The invention describes a method for adjusting an engine operating parameter to maintain transmission input speed at or below a synchronous transmission input speed when the transmission is in the gear with the over-running clutch. The synchronous transmission input speed is based on transmission state and transmission output speed. Alternatively, vehicle speed can be used in place of transmission output speed.

Abstract: Method and electronic control system using a unique driver demand (calibration) table stored in system memory to provide torque output values specific to a 4×4 mode of operation of the vehicle drive unit. For example, the torque output of the electronic control system for a 4×4 low mode of operation is controlled using a unique calibration table stored in system memory for 4×4 low mode of operation, while the torque output of the electronic control system for other modes of operation is controlled using one or more different, other calibration tables stored in system memory.

Abstract: A method and system for operating a lean-burn internal combustion engine in cooperation with an exhaust gas purification system having an emission control device, wherein the system includes a controller which calculates current levels of a selected exhaust gas constituent, such as NOx, during lean engine operating conditions based upon the difference between a determined instantaneous feedgas NOx concentration and a determined instantaneous device efficiency. The controller discontinues lean engine operation when the tailpipe NOx, expressed in terms of either grams-per-mile or grams-per-hour, exceeds a predetermined threshold level, either instantaneously or as averaged over the course of a device purge-fill cycle.

Abstract: A method is described for limiting a change in torque transmitted through a vehicle powertrain when in a predetermined range. Such a method minimizes transmission gear separation, or “clunk”. In one approach, the rate of change of powertrain output is limited when powertrain output is near zero transmitted torque. The limitation is not used under other circumstances so as not to hinder driver performance.

Abstract: A method for controlling cycling of an air conditioning compressor coupled to an internal combustion engine interrupts normal cycling based on operation conditions. In addition, normal engaged and disengaged cycling durations are adaptively estimated in real-time. The method of the present invention achieves improved fuel economy and improved drive feel. As an example, improved fuel economy is achieved by engaging the compressor during braking or when the engine is being driven by the vehicle. As another example, improved drive feel is achieved by engaging the compressor during transient conditions when drive feel is unaffected.

Abstract: A method and system for controlling the operation of “lean-burn” internal combustion engines determines a current rate of vehicle NOx emissions, and determines a threshold value for permissible vehicle NOx emissions based on at least one current value for the intake air-fuel ratio, engine speed, engine load (e.g., brake torque, manifold air pressure, or throttle position), and/or vehicle speed. A differential NOx emissions rate is calculated as the difference between the current rate and the threshold rate, and the differential rate is accumulated over time to obtain a differential measure representing the amount by which cumulative NOx emissions have fallen below permissible levels therefor. Lean engine operation is disabled when the differential NOx emissions measure exceeds a predetermined excess vehicle NOx emission value. In this manner, vehicle NOx emissions are favorably controlled even when the engine is operated “off-cycle,” i.e.

Abstract: A method and system for diagnosing catalyst operation in an internal combustion engine having a two-bank, three EGO sensor structure includes determining the ratio of the arc length between the post-catalyst EGO sensor signal and the arc length of a pre-catalyst EGO sensor signal over a selected time period. If the exhaust bank is a one-sensor bank having only a post-catalyst EGO sensor and no pre-catalyst EGO sensor, the system uses the arc length from the pre-catalyst EGO sensor in the two-sensor bank to calculate the arc length ratio, thereby allowing calculation of two arc length ratios without two matched pairs of EGO sensors. The ratio indicates the efficiency of the catalyst and may be compared with calibratable or experimentally-determined thresholds to monitor converter efficiency over time.

Abstract: Optimum MBT and BDL ignition timing value are obtained from calibration values stored in stability limited (SL) and optimum power (OP) calibration tables using a power index (PI) value that is indicative of the relative desire of the driver for fuel economy or power to interpolate over the range of values in the SL and OP tables to calculate values of MBT and BDL that are optimal for all altitudes and levels of driver demand. The ignition timing value used at any point in time is preferably the lesser of the MBT value and the BDL value. The calibration values for MBT and BDL ignition timing are associated with cam timing values in cam timing tables so that ignition timing changes in lock step with the cam timing.