Electronic fuel injection system is the key electronic control system in the modern automobile.It can precisely control the fuel quantity and the ignition time based on the inlet flow

and the fuel can nearly burning on the theoretical air-fuel ratio.The property of better security

economy

power parameters and less emission of automobile will implement.So precise measurement of the inlet flow is very important.The present status

characteristics

problems and the future trend of the air-flow sensing technique for the electronic fuel injection system are introduced.And then a kind of measurement method which combined the theory of parallel plate capacitor with the vortex is presented.