Minimum engine torque, 4x: General: Dashpot

To avoid jarring when suddenly decelerating, the dashpot function will request engine torque for a brief period so that it can then be reduced gradually. This also reduces emissions.

Fig 1: Identifying RPM Pattern - Dashpot

Courtesy of SAAB-SCANIA OF AMERICA, INC.

You can compare this function with the throttle damper on older injection or carburetor cars where the throttle movement towards idling was slowed down.