Abstract: The fuel control routine of an engine control module sets a cold enrichment schedule used for engine starting when the engine is cold. The enrichment value is dependent on coolant temperature. To prevent plug fouling in a new vehicle subject to short engine run times, the enrichment value is reduced if the mileage is below 50 miles, the coolant temperature is within set limits and the previous engine run time was shorter than a set period.

Abstract: An idle speed control motor under computer control positions a throttle stop for setting minimum throttle angles. The motor response to actuating pulses varies from motor to motor so that a gain factor is determined for each motor and is used to calculate the required pulse width to attain a desired throttle displacement. A gain learn program in the engine control computer runs when the ignition is turned off and is effective to extend the motor with a number of pulses of known width, measure the throttle displacement, and determine the gain factor by dividing a standard displacement by the measured displacement. The same program is applied to learning the gain of a throttle motor in an electronic throttle control system.

Abstract: In a method of traction control, fuel injectors are selectively disabled to unfuel respective cylinders of an engine to reduce engine torque output. The method provides for limiting the number of cylinders that can be disabled for acceleration spin control based on engine and vehicle operating parameters to improve traction control performance and provide protection for the vehicle catalytic converter.

Abstract: A communication method provides for an exchange of a multiple byte message between two processors. Interrupt suppression associated with the message transfer is minimized by alternating the processors between master and slave operating modes with each byte exchanged.

Abstract: The ratio air and fuel mixture delivered to the fueled cylinders of an engine of a vehicle is controlled while selective cylinders of the engine are unfueled to reduce engine torque output to inhibit excessive wheel spin during vehicle acceleration. The air/fuel ratio of the mixture delivered to the fueled cylinders is increased as cylinders are selectively unfueled to reduce engine torque output and power enrichment to the fueled cylinders is inhibited when any cylinders are unfueled to reduce engine torque output for traction control and for a time period after all cylinders are again fueled.

Abstract: A throttle follower controller for establishing a release throttle position upon the release of the throttle by the vehicle operator which is maintained at a specified value for a predetermined time if the vehicle transmission is experiencing an upshift or if an upshift will occur upon the release of the throttle to provide for a smooth upshift. Upon completion of the upshift or if no upshift will occur upon release of the throttle, a controlled transition of the throttle angle to a predetermined lower coastdown value is established to prevent drive-on while preventing a sudden harsh drive line jerk upon release of the vehicle throttle.

Abstract: Potentially damaging operation of a viscous converter clutch (VCC) is detected in relation to the slippage thereacross. The slippage is compared with a reference slip value indicative of excessive VCC slippage to develop a net overslip indicator. The value of the net overslip indicator changes in the direction of a first limit value so long as the detected slip is at least as great as the reference slip, and in the direction of a second limit value so long as the detected slip is less than the reference slip. When the net overslip indicator reaches the first limit value, the friction clutch is disengaged to release the VCC. According to a first embodiment, the transmission fluid temperature at the time of such deactivation is measured and stored, and the VCC is reactivated when transmission fluid temperature falls below the stored temperature, assuming other criteria for activation are also met.