Abstract: Internal combustion engine misfires are diagnosed through monitoring of change in engine speed wherein an acceleration spike index is generated for each cylinder event over a number of engine cycles in a test period and is corrected in accord with sensed part tolerancing, and wherein the corrected acceleration spike index is compared to at least one misfire threshold. For each engine cylinder, a degree of misfire severity is diagnosed at the end of the test period in accord with the frequency of excursions by the corresponding misfire index above the at least one misfire threshold.

Abstract: An improved powertrain control which recognizes the occurrence of positive engine torque caused by accelerator walk-in by the operator during coast-sync-coast downshift, and effectively prevents or arrests speed flare via engine torque management controls. The engine spark timing is normally not responsive to coast-sync-coast downshift conditions, however, when the occurrence of accelerator walk-in results in excessive positive engine torque likely to cause, or actually causing, engine speed flare is detected, spark retard is controlled to a predetermined value, thereby controlling the transmission input torque and allowing smooth application of the on-coming element for completion of the shift.

Abstract: A lubrication system for multi-plate clutch assemblies is controlled to provide increased lube flow. During steady state operation, lube flow is increased periodically for a short time interval. At other times during steady state operation, the lube flow is maintained at a level requiring minimum fluid flow for the system.

Abstract: In a motor vehicle power train including a fuel injected internal combustion engine and a hydraulic automatic transmission, an improved engine fueling control strategy for maintaining proper engine RPM in the presence of an automatic transmission Park or Neutral (P/N) to Drive or Reverse (D/R) range shifting. Communication between the Engine and Transmission Control Modules enables precise anticipation of rapid engine intake manifold absolute pressure (MAP) increases associated with P/N to D/R range shifting. Additional fuel is injected immediately preceding the MAP increase in order to maintain the proper engine air/fuel ratio necessary to prevent RPM sags and engine stalls during the clutch engagement. Once the clutch engagement is complete, the additional fuel is progressively eliminated.

Abstract: A shift pattern control for a multiple speed ratio transmission wherein an inference-based control overrides the normal shift pattern to automatically achieve manual pulldown operation under conditions for which such operation would be advised and expected. The inference-based control is achieved with a fuzzy logic technique by which vehicle parameters influencing the desirability of manual pulldown operation are measured or estimated, and used to establish an aggregate measure of the overall need for engine braking and downshifting. In the preferred embodiment, the fuzzy logic parameters include vehicle speed, grade load, engine throttle position, time of braking and time of deceleration. The parameters are applied to membership functions to indicate the truthfulness of the specified conditions, and logical combinations of the truth indications are formed, weighted to reflect their criticality, and combined to form an aggregate measure of the overall need for pulldown operation.

Abstract: A traction control system provides coordinated use of axle torque management via engine spark, engine fuel, and transmission gear ratio. Primary torque management is provided by retarding the ignition timing to reduce engine torque. When the spark retard reaches a determined limit value, the vehicle automatic transmission is upshifted which reduces axle torque and engine speed, thus reducing the amount of spark retard required to control a slip condition, thereby increasing the authority of the spark retard system. The limit spark retard threshold is established as a function of the temperature of the catalytic converter so as to prevent an overtemperature condition. Further, fuel control is ultimately used if control of ignition timing is incapable of bringing the acceleration slip under control. This condition may exist, for example, when the spark system authority of control is insufficient due to limitations placed upon its authority in response to a sensed hot catalytic converter condition.

Abstract: An improved control of a motor vehicle torque converter clutch (TCC) which detects a condition of TCC engagement when open converter operation is required, and activates an override mechanism to disengage the TCC independent of the normal TCC control in response to the detected condition. This ensures that the TCC is disengaged when open converter operation is required, thereby permitting continued operation of the vehicle in conditions where the vehicle would otherwise be inoperable. When unwanted TCC engagement is detected, the control activates a clutch priority valve by intentionally commanding the engagement of two or more range clutches. When so activated, the clutch priority valve exhausts all but one range clutch and hydraulically disables engagement the TCC. When the vehicle speed is sufficiently high to permit TCC engagement, all but one of the range clutch pressure commands are eliminated, and the clutch priority valve returns to a normal state to permit TCC engagement.

Abstract: An improved torque converter clutch (TCC) engagement control method utilizing a combination of pressure control and flow control methodologies to ensure consistently smooth and timely TCC engagement. The engagement is initiated with a pressure control methodology in which the duty cycle of a PWM actuator is selected to produce a desired pressure differential across the TCC clutch plate. However, if the flow conditions are such that the pressure control methodology fails to promptly initiate engagement of the TCC, as detected in relation to the speed difference across the torque converter, a flow control methodology is substituted for the pressure control to initiate clutch engagement. In this case, the duty cycle of the actuator is adjusted to a value which provides full or near-full fluid flow. This control is maintained for a predetermined period, or until the speed difference across the torque converter indicates initiation of TCC engagement.

Abstract: An improved shift pattern control in which successive upshifting and downshifting is avoided in conditions of above normal loading by inhibiting upshifting to a speed ratio having insufficient gradeability in relation to a measure of the actual loading. In essence, the control continually monitors the gradeability of the various forward speed ratios of the transmission in relation to a measure of the actual grade load to determine their excess gradeability, and removes from the shift pattern those speed ratios having insufficient excess gradeability. This ensures that the transmission will never be upshifted to a speed ratio that has insufficient gradeability for the given driving condition, thereby eliminating the successive upshifting and downshifting which occurs with conventional shift controls.

Abstract: A control valve arrangement for a torque converter and clutch assembly is operable to control the torque converter outlet pressure at one pressure level during clutch engagement and at another pressure level during clutch disengagement.

Abstract: A power shutdown sequence provides for an orderly power shutdown for master and slave processors sharing a single power supply while at the same time allowing the master and slave processors to retain all the information learned regardless of failures. If the master senses a shutdown condition, it sends the slaves a power down signal confirming its intention to power down the system and commanding the slaves to initiate shutdown procedures, including the storing of variables to memory. In addition, the master also initiates shutdown procedures, and after a minimum time determined sufficient to allow the slave to complete their shutdown procedures, the master powers down the system. The slaves may also initiate their own powerdown procedures if a failure in the communications link with the master is sensed.

Abstract: A transmission shift control having both multiple shift pressure moding and adaptive pressure schedule adjustment. A predetermined pressure schedule is used to develop an open-loop pressure command for the post-fill phase of the on-coming clutch in each upshift. Regardless which shift mode is selected, the controller measures the duration of the shift and compares the measured duration to an expected duration which will occur if the shift progresses as desired. The deviation, if any, is used to develop an adaptive correction amount, which is applied to shift mode dependent tables. In the base (Normal) mode, the pressure is determined in accordance with the pressure command from the predetermined pressure schedule, adjusted by an adaptive correction amount from a Normal mode correction table. In the Performance mode, the pressure command from the predetermined schedule is adjusted by adaptive correction amounts from both the Normal mode correction table and a Performance mode correction table.

Abstract: An improved powertrain control which recognizes the occurrence of engine speed flare during low torque upshifting, and effectively converts the shift to a power-off upshift via an override of the normal engine torque management controls. The engine spark timing is retarded by a predetermined amount during every power-on upshift for the reasons described above. However, when the occurrence of engine flare is detected, the control increases the spark retard to a maximum valve, substantially eliminating the transmission input torque. As the on-coming element smoothly applies and decelerates the input, the flare condition terminates, and the spark timing is returned to the predetermined amount for completion of the shift.

Abstract: An open-loop clutch-to-clutch shift control system wherein the overlap between off-going and on-coming clutches in an upshift is regulated in accordance with a confidence term determined through a self-estimation by the control system of its ability to accurately determine the on-coming clutch fill time, and thus, its ability to effect a precise exchange of the off-going and on-coming clutches with little or no overlap. Under certain conditions, the confidence level is assumed to be low, and the clutches are controlled to result in a relatively high level of overlap. As the level of confidence improves, the timing of the clutch exchange is adjusted to reduce the level of overlap. When the level of confidence is high, the exchange of clutches is effected with almost no overlap.

Abstract: An ignition timing system generates ignition timing pulses from a basic ignition timing, a current knock retard and an adaptive knock retard. It includes a plurality of memory cells in a one-dimensional lookup table referenced to predetermined engine speeds and determines the adpative knock retard by multiplying a number derived from the cells at the current engine speed by a load gain factor based on current engine load. It updates the cells on a fixed time period basis. When sufficient knock has occurred in a time period, an increase is applied to the one or more cells closest to the engine speed at which knock first occurred during the period, with the amount of increase based on the maximum current knock retard during the period. Thus, updating is frequent and may occur even in transient conditions; and the correction is focused on the engine speed at which knock was initiated so as to prevent such knock initiation in the future.

Abstract: An adaptive pressure control for an automotive transmission in which the fluid pressure developed by an electro-hydraulic actuator is directed to a plurality of fluid operated torque establishing devices, wherein adaptive pressure corrections occasioned by actuator variability do not impair shift quality in operating regions known to be substantially free of actuator variability. Separate adaptive correction amounts are provided for each torque establishing device, and the amounts are compared to determine the portion, if any, occasioned by actuator variability. Such portion is utilized as a correction to an open-loop scheduled pressure to a degree which depends on the magnitude of the scheduled pressure.

Abstract: An adaptive transmission pressure control based on a measured interval of speed ratio progression includes a closed-loop control which compensates for factors that tend to extend the speed ratio progression. The control detects the rate of speed ratio progression during a first portion of the inertia phase of the shift, and employs closed-loop pressure control to maintain the detected rate of progression through completion of the shift. This ensures that the measured progression interval will accurately reflect the relationship between the scheduled pressure and the resulting shift ratio progression, regardless of factors which would otherwise influence the measured shift progression interval. Consequently, the correlation between shift quality and the measured shift progression interval is preserved.

Abstract: An improved method of scheduling ratio shifting in a vehicle transmission adaptively adjusts the normal shift schedule to avoid shift-related overheating of the torque transmitting devices of the transmission. In normal operation, transmission shifting is scheduled by comparing measured vehicle speed and engine throttle position values with predefined load data. In the background, the transmission controller determines the cumulative thermal energy stored in the torque transmitting devices. If excessive energy is indicated, the normal shift schedule is modified to allow extended operation in the lower speed ratios. When the cumulative energy indication returns to a normal level, normal shift scheduling is resumed.

Abstract: A transmission controller in which the throttle position sensor signal is used to determine the throttle position so that proper shift selection may be carried out. In the event that the throttle position sensor malfunctions, a value is calculated for the throttle position based upon the manifold atmospheric pressure, then used in place of the actual value for throttle position. Such a substitution remains in effect until the throttle position sensor is properly functioning once again and the actual value for the throttle position is suitable close to the calculated value so that reversion to the actual value will occur without causing shifts that will surprise the driver who is not expecting any such shift.

Abstract: A mechanical clutch is provided to selectively interconnect a forward or reverse gear member to a transmission shaft. The clutch is operated by a servo piston and fork structure. The servo piston is slidably disposed in a housing and urged in the forward select position by a spring. The housing and servo piston cooperate to define two fluid chambers which are maintained in a separated condition when the forward select position is established. One chamber is in fluid communication with a fluid system that is controlled to provide fluid at two distinct pressure levels, depending upon various vehicle operating parameters. The other chamber is connected with a selectively engageable fluid operated friction clutch which is effective to assist in establishing at least the reverse drive ratio within the transmission. The lowest level of fluid pressure in the one chamber is not sufficient to cause the piston to overcome the spring force and thereby move the clutch to the reverse select position.