A flow regulator for automotive vehicles of the type having a computer-controlled emission control system. The flow regulator has an electric vacuum regulator (EVR) valve that regulates the vacuum signal provided to a vacuum regulator valve in accordance with the current signal supplied to the EVR valve by the engine controller unit. The vacuum regulator valve includes a control chamber and a valve chamber that are separated by a movable diaphragm valve assembly. The preload on a biasing spring acting on the diaphragm valve assembly can be adjusted during calibration of the flow regulator for setting a first calibration point. An adjustable flow restrictor provided in the inlet portion of the vacuum regulator valve can be varied during calibration for setting a second calibration point. In operation, the flow regulator is operable to generate substantially linear output flow characteristic between the two calibration points as a function of the current signal in a manner that is independent of changes in manifold vacuum.