1. Method for operating a vehicular powertrain including an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine, said electro-mechanical transmission selectively operative in one of a plurality of continuously variable and fixed gear operating range states, the method comprising: commanding operation of the electro-mechanical transmission in one of the continuously variable operating range states; commanding operation of the engine in a closed-loop speed control mode, the closed-loop speed control mode always comprises operation of the engine; monitoring operator inputs; monitoring a transmission output shaft speed measured by a transmission output speed sensor; and terminating operation of the engine in the closed-loop speed control mode when a time-rate change in the transmission output shaft speed exceeds a threshold absent a change in the monitored operator inputs.