A powertrain system includes an engine coupled to a multi-mode transmission configured to transfer tractive torque to an output member coupled to a ground wheel. A method for operating the powertrain system includes identifying an undesirable operating region for the multi-mode transmission associated with driveline growl including an input torque range and an output torque range. In response to a command to traverse the undesirable operating region from a first operating region to a second operating region, a fast engine torque transition is executed including controlling the engine as a fast-adjusting torque actuator to control input torque from the engine to the multi-mode transmission and correspondingly controlling motor torque from a torque machine to the multi-mode transmission to maintain output torque from the multi-mode transmission responsive to an output torque request while traversing the undesirable operating region from the first operating region to the second operating region.