Abstract: A variable power drivetrain engine control system for a heavy duty vehicle such as a tractor/trailer combination or truck is disclosed. The engine control system provides higher output capability for the engine of the vehicle in accordance with certain detected conditions. If the vehicle speed falls a predetermined DELTA miles/hour below a LEARNED SPEED of the vehicle, the engine is enabled to operate at a higher power output capability until the vehicle resumes the LEARNED SPEED. Further, high output capability is enabled when the vehicle deceleration is in excess of a predetermined deceleration rate. Again, the high output capability is disabled once the vehicle retains the LEARNED SPEED velocity. The quantity DELTA can be variable with respect to actual vehicle speed to provide more responsive operation of the variable power drivetrain system thereby providing improved responsiveness to road conditions in accordance with relative vehicle speed.

Abstract: A microprocessor engine control for a diesel engine powered truck is provided with a grade-holder vehicle speed control by another algorithm that is effective to cause the engine operation to move from one horsepower vs. speed curve to another when the vehicle encounters a change in load, such as when the vehicle encounters a change in grade.

Abstract: A microprocessor engine control for an internal combustion engine powered truck is provided with a clutch priority engine speed control by the inclusion of a clutch pedal switch for sensing incipient clutch engagement at vehicle launch. The microprocessor executes an algorithm that takes control of engine speed away from the driver until the launch is successfully completed. The algorithm causes the engine to operate at a speed that has been predetermined to minimize wear and tear on the powertrain. The algorithm includes a false start feature that resets the alogrithm in the event of an aborted launch.