Method and apparatus to determine rotational position of an internal combustion engine

A control system for a hybrid powertrain which determines engine crank angle position based upon signal inputs from electric machines of the powertrain is provided. The hybrid powertrain comprises an internal combustion engine and electric machines and an electro-mechanical transmission selectively operative to transmit torque therebetween. The electric machines are rotatably fixedly coupled to the internal combustion engine via a transmission input shaft. Control modules are adapted to execute a control scheme to determine engine crank angle position. The control scheme comprises code to determine an input shaft angle based upon rotational positions of the electric machines. An offset angle of the input shaft and an angular twist between the engine and the transmission are determined. An engine crank angle offset is determined based upon the offset angle and the angular twist of the input shaft.