An internal combustion engine includes an advanced vehicle system
controller (VSC) that calculates a total power demand to meet a driver
wheel power demand plus any accessory loads and independently schedules
an engine speed and load operating point to meet the total power demand.
A reduction in available engine brake power that is not associated with a
driver input, and would ordinarily cause the VSC to respond by raising
engine speed, is detected. The driver wheel power demand is reduced to
compensate for the reduction in available engine brake power such that
the VSC does not need to raise engine speed to meet the driver wheel
power demand. A magnitude of the reduction may be determined according to
a calibration map to allow a trade off to be made between driveability
and noise, vibration, and harshness.