Abstract: A system and method for monitoring engine performance utilizes a monitoring micro-controller that integrates with an engine/vehicle controller to receive data indicative of the current operating conditions of the engine/vehicle. A duty cycle map is defined within the micro-controller by a plurality of sectors bounded by a specific performance curve based on two or more engine operating parameters, such as engine torque and speed. Each sector corresponds to a range of values for the specific operating parameters. During iterations of the monitoring routine, current data indicative of the specific engine operating parameters is sensed and compared with the range of values for each duty cycle sector. A duty cycle parameter, such as elapsed time or fuel consumption, is maintained for each sector. When the current engine operating conditions fall within a particular target sector, its corresponding duty cycle parameter is updated.

Abstract: In a microprocessor-based automotive control system including flash memory and a RAM cache sized substantially smaller than the storage capacity of the flash memory, a caching technique is operable, in accordance with one aspect of the invention, to move areas of the flash memory into and out of the cache. The flash memory is updated by the contents of the cache each time the a new access is attempted to an area of flash memory or after a predefined time period has elapsed since such an access has been attempted. In accordance with another aspect of the invention, 9 bit storage within the flash memory is disallowed and only word (16 bit) or longword (32 bit) storage is allowed therein, so that the flash memory is addressable only on even boundaries thereof. A software algorithm is operable to modify a request for access to an odd flash memory address so that the request properly points to an address of the cache that contains the actual data of interest.

Abstract: A fault recognition system is implemented as an adjunct to fault determination software of an on-board engine control module (ECM). The ECM activates a "Type A" or "Type B" fault code for each signal received from a plurality of sensors disposed about the engine when that signal exceeds a predetermined threshold. A "Type C" fault is recognized and activated when all of a predetermined group of underlying "Type A" or "Type B" fault codes have been activated. The "Type C" fault is displayed, while the underlying faults may or may not be displayed. The "Type C" fault provides a better and more immediate indication of the source of the engine problem than any of the underlying faults. Only those underlying faults that aid in the recognition of the source of the engine problem are displayed. The remaining faults underlying the "Type C" fault are masked. When the "Type C" fault becomes inactive, any underlying fault codes are unmasked for subsequent evaluation.

Abstract: A system and method for detecting and correcting power imbalance between cylinder banks of an internal combustion engine utilizes, in one embodiment, temperature sensors at the exhaust manifolds for each cylinder bank. A differential temperature value .DELTA. is generated and used to determine which cylinder requires modification of its operating conditions to equalize the power output between the opposing banks. In one embodiment, the sign of the value .DELTA. is used to determine which cylinder bank has the highest exhaust temperature, and the value .DELTA. is provided as a multiplier to engine operating algorithms implemented by the engine control computer to derate the subject cylinder bank. In another embodiment, the value .DELTA. is used to uprate the bank having the lower exhaust temperature, indicative of a lower power output.