This is some notes that I borrowed.
Air Flow Sensor Potentiometer
This is one of the very important pieces of the system. It is operated by the air flow sensor, the circular metal plate that deflects under the influence of the air flowing into the engine, which in turn is determined by the throttle opening. It is a fair bit more complex than a volume control on your stereo, but it does the same thing. As the air flow sensor is deflected by the air stream, the shaft upon which it rotates moves sliding contacts over a track of resistive material and this feeds the computer with a voltage reading which allows it to control the precise amount of fuel required by the measured air flow. Now every time the throttle is operated, the air flow sensor deflects and moves the sliding contacts across the resistance material and that can happen a few million times, I guess, in the lifetime of a car. So the track wears and the computer can then be fed with a certain voltage at one throttle opening and with just a very small movement the sliding contacts encounter an area where no resistance material remains, so the voltage indicating air flow drops to zero. The computer doesn’t know what to do, so erratic operation is the result.
Post time: Aug-22-2017