Abstract: A maintenance method for periodically maintaining the operating condition of an exhaust gas recirculation valve for controlling recirculation of internal combustion engine exhaust gas from an exhaust gas path to an engine intake air path in which the valve is periodically driven to a maximum open position and then back to an initial position, such as a closed position when engine operating conditions are such that there is no driveability or emissions penalty associated with such valve maintenance and when sufficient battery drive voltage is available to drive the valve as required for maintenance thereof.

Abstract: In a powertrain including an internal combustion engine coupled to a transmission, engine ignition timing is controlled to minimize the impact of severe mechanical load disturbances, such as resulting from transmission shifts into or out of park or neutral positions, wherein the ignition timing is gradually varied to match the characteristic of the load disturbance being compensated, and variation in ignition timing is delayed in accord with transmission responsiveness, such as indicated by transmission temperature, until the disturbance is actually impacting powertrain mechanical load. Control stability is improved by temporarily suspending potentially duplicate control operations until the mechanical load disturbance has been compensated.

Abstract: Integrated dilution control for diluting internal combustion engine intake air through control of relative timing between engine cylinder intake and exhaust valve events integrated with control of recirculation of engine exhaust gas through an external exhaust gas conduit with periodic recalibration of modeled relationships between dilution control parameters to correct for effects of dilution control system aging. Internal dilution provided through control of relative valve timing further may be maximized and external dilution provided through the external conduit minimized.

Abstract: Internal combustion engine control and diagnostics provides for delivery of a fuel quantity and intake air to engine cylinders and for an ignition signal to ignite the air and fuel, wherein misfire conditions in the cylinder are diagnosed over all operating conditions through a reference period model of the components of measured reference periods not attributed to a misfire condition and through removal of such components from measured reference periods yielding a resultant reference period component sensitive only to misfire conditions. The magnitude, position, and stability of the resultant component indicates misfire severity, location, and persistence.

Abstract: A spark plug boot assembly providing for simplified assembly of a tubular boot and an ignition cable having a terminal with a circumferential rib or protuberance thereabout, wherein the tubular boot includes a plurality of aligned bottom stops spaced along the longitudinal boot axis from a plurality of aligned flexible arms reaching into a central boot bore, with a bi-directional locking position formed between the bottom stops and the flexible arms for locking, upon full insertion of the ignition cable through the bore, the rib or protuberance in the locking position.

Abstract: An automotive internal combustion engine air/fuel ratio control system is diagnosed by monitoring the oxygen content of catalytically treated engine exhaust gas for sustained deviations into regions of saturation in which the catalytic treatment device is characterized by low treatment efficiency. The oxygen content of catalytically treated engine exhaust gas is periodically sampled under test conditions and the samples processed into representative values for comparison to a predetermined range. Persistent excursions outside the range indicate a fault condition in which the air/fuel ratio control system operation is not supportive of efficient exhaust gas aftertreatment.

Abstract: Internal combustion engine air/fuel ratio control provides for individual engine cylinder air/fuel ratio balancing through sensing of individual cylinder air/fuel ratio and through comparison of sensed individual cylinder air/fuel ratio to a target air/fuel ratio with air/fuel ratio control command correction prescribed on a cylinder-by-cylinder basis. The target air/fuel ratio may be determined as an overall average cylinder actual air/fuel ratio. An additional control loop is provided for driving a value representing overall engine air/fuel ratio toward a desired air/fuel ratio, such as the stoichiometric ratio. Correction values are learned gradually for each engine cylinder and stored and recalled as a function of an engine operating level.

Abstract: Automotive vehicle electronic devices are diagnosed through communication with a flexible diagnostic tool which automatically switches between a wide variety of communications protocols as required for diagnostic communication tasks presented to the tool. Simultaneous communication with a plurality of devices under a plurality of communications protocols is supported by the tool wherein communication hardware is available for parallel communications under the various protocols via various communication channels and is apportioned for each active diagnostic communication task for the duration of that task.

Abstract: Integration of vehicle speed and engine control functions in an automotive vehicle internal combustion engine controller compensates for mechanical lash between a cruise control actuator and an engine intake air valve without sacrificing control responsiveness through a parallel control approach, and improves overall control stability and controllability in the absence of mechanical lash through a selective control approach established to provide for smooth transitions between control modes. Improvement in the integration of deceleration fuel cutoff control with cruise control operates to prevent torque disturbances caused by control transitions in sensitive engine operating regions.

Abstract: Control and functional isolation of an actuator applied to an internal combustion engine through an interface module which is interposed between the actuator and a controller having a control function, with state of the actuator estimated, converted to standard units of measure, and corrected in the interface module in response to an estimate of a parameter influenced by the actuator state, the parameter expressed in the standard units of measure, and the corrected state applied as feedback to the controller which, through application of the control function, issues to the module a desired state. The desired state is restored by removing a correction value from the desired state, is converted to actuator position units, and is applied to control actuator position.

Abstract: Ignition drive circuitry for generating sequential first and second arcs across electrodes of spark plugs in internal combustion engine cylinders for contributing supplemental combustion energy and for enabling simple, robust misfire detection with a first arc generated through rapid discharge of a storage element and the second arc generated through interruption of said discharge through a transformer primary ignition coil.

Abstract: A self-diagnosing ignition drive circuit for applying a first ignition drive signal to a spark plug in an internal combustion engine cylinder for generating an arc across the electrodes thereof to ignite an air/fuel mixture in the cylinder and, following a delay period, applying a second ignition drive signal to the spark plug for generating a second arc across the electrodes to contribute combustion energy and to provide for measurement of the frequency content of energy trapped in an ignition coil during combustion. If the frequency content includes a predetermined frequency, improper ignition in the cylinder is diagnosed through excitation of a natural frequency of a misfire detection circuit coupled to the ignition coil corresponding to at least one engine cylinder.

Abstract: A solderless filter circuit disposed in an electrical connector assembly for filtering electrical signals carried by conductors in the connector assembly including, without solder connections, low cost capacitive and inductive circuit elements providing reliable electrical connection with the conductors, for example in a Pi filter configuration for low pass signal filtering in a convenient filter package. Integrated capacitor elements include modified electrical leads in the form of conductor seats and are packaged with a ferrite block in at least one housing retained within at least one of two mating connectors.

Abstract: Paint flow control interface circuitry for passing electrical signals across a paint booth barrier including a feedback signal indicating a paint flow parameter from a parameter transducer within the paint booth, includes passive resistive intrinsically safe barrier circuit elements coupled with buffer circuitry for minimizing the voltage drop across the interface circuitry. Light filtering of the buffer circuitry output signal with minimum filter lag yields an accurate indication of the paint flow parameter with high signal to noise ratio and minimum signal lag, for application in closed-loop paint flow control. Additional transducer voltage supply signal feedback provides for closed-loop voltage supply control across the interface circuit.

Abstract: Automotive controller lookup table reference values are reduced as necessary so as to be stored in standard controller memory device locations by reducing, through a minimum number of standard reduction values, the magnitude of any reference value requiring more than one standard location for storage and by recording the number of standard reduction values applied to each reference value so that, upon retrieving any one reference value, the proper magnitude adjustment may be expediently made thereto to restore the reference value magnitude to its original value.

Abstract: Internal combustion engine exhaust gas recirculation (EGR) system diagnostics provides for intrusive analysis of the performance of the EGR system in two phases which are alternately activated while the engine is in a stable, hot idle operating region. A first phase approximates EGR system performance through an abbreviated opening of an EGR valve to permit a limited amount of EGR pass to an engine intake air passage so that limited measurement of the effect of the EGR on intake air passage pressure may be made with minimum disruption of engine performance and emissions control performance. If the first phase indicates a potential EGR system problem, the second phase is activated and the first phase is deactivated.

Abstract: Significant restriction in an automotive internal combustion engine intake air filter is diagnosed over a wide range of engine operating conditions including low intake airflow rate conditions by qualifying transduced pressure drop across the air filter using airflow rate through the filter. A diagnostic count is maintained and updated in accord with detected significant restriction conditions. Adjustment values applied to the diagnostic count vary in accord with the degree of confidence associated with each detected significant restriction condition, such as indicated by varying engine intake airflow conditions.

Abstract: Engine control responsive to temperature modeling error during an engine startup period following an engine latency period through time measurement of the latency period and modeling of the effects of the latency period length on a difference between a measured temperature parameter and the temperature of certain critical engine parts, such as engine cylinders, intake valves, fuel injectors etc. Compensation may be provided through variation of an engine fueling command during an engine startup period including during engine cranking as a function of temperature measurements and of the time length of the latency period. The compensation may decay gradually toward zero compensation as the modeling error decreases.

Abstract: Resolution of redundant displacement sensor information to form a displacement value in an automotive electronic throttle control system provides for a varying contribution by each of a plurality of redundant sensors to the formation of the displacement value in accord with diagnosed variations in the fault status of the sensors. The number and type of fault conditions attributed to a specific sensor of the plurality over an analysis period are used to determine the relative degree by which that sensor will contribute to the displacement value formation. As an increasing number of fault conditions are attributed to a sensor, the relative degree of contribution of that sensor will gradually decrease. When severe fault conditions are attributed to a sensor, the relative degree of contribution of that sensor will rapidly decrease.

Abstract: Integrated control of internal combustion engine fueling including control of fuel injectors and control of purge valve position to vary the rate at which fuel vapor trapped in a canister is purged to an engine intake manifold, determines the mass of purge vapor reaching the intake manifold, estimates the mass of purge vapor reaching each engine cylinder, and adjusts the engine cylinder fuel injection mass in response thereto to provide an accurate overall cylinder fueling insensitive to the purge rate, allowing the purge control operations to be aggressively driven while ambitious cylinder air/fuel ratio standards are maintained. Feedforward purge control proactively adjusts purge control commands in response to desired cylinder purge mass and to purge vapor flow dynamics and feedback purge control trims the purge control commands in response to a difference between the desired cylinder purge mass and estimated cylinder purge mass.