A low pressure drop air flowmeter for an automotive engine is disclosed. The meter includes a main air flow passage, a relatively small venturi tube receiving a portion of the air flow, a pressure port for sensing stagnation pressure in the main passage, a pressure port for sensing static pressure in the throat of the venturi, and a set of stationary swirl vanes disposed adjacent the outlet of the venturi and operative to impart a swirl to the remainder of the air in the main passage, thereby creating a reduced pressure at the venturi outlet for amplifying the pressure difference between the stagnation and static pressures without appreciably increasing the pressure drop across the flowmeter. Also disclosed is a solenoid valve having a single valving member operative in one position to communicate the stagnation pressure to an absolute pressure transducer and operative in another position to communicate the static pressure to the transducer.