Uphill-Driving Detection

Compared with driving on a level surface, tractive resistance during uphill driving increases by the component of the downgrade force. This requires increased engine power to maintain a constant speed. Increased engine power is achieved by having the throttle open at a slightly later stage. A downshift to a lower gear occurs to increase the engine speed depending on the road speed. Assuming that the speed is to be kept constant, the throttle valve angle must now be reduced, which in turn would result in an upshift. The result would be damaging back-and-forth shifting if the gradient were to be negotiated at a constant speed. Characteristic maps are stored in the control unit's software to suppress shifting of this type. The characteristic maps suppress back-and-forth shifting and provide the engine with the optimum traction force.