I was looking at my AFM from my 87 TII and I just kept asking myself why. Mainly what i want to know is how that little flap works and if its necessary or not. I dont think the s5's have them do they??? Basically what i was thinking was...Could I just make a 3" pipe going all the way from my turbo to my cone and just drill a hole and insert the sensor?? Im sure theres much more too it but thats all I could come up with for now. Can anyone enlighten me?

 

The faster your car is moving, and the higher the RPM's of the engine, the more air being sucked into your intake cone. As air goes through the AFM, the air pressure pushes on a flap with a spring. There is an electrical connection connected to AFM that sends the signal back to the ECU how much air is being sucked in.

 

k, cool
do the 89-91's have the flap too?? I noticed that the flap dosent actually seal anything so is it really necessary?

 

Well sort of, its not realy a flap, its a cone shaped thing that moves forwards and backwards. The only way you can get rid of it, is to go Haltech, or some other stand-alone computer. Otherwise your car will not run. As far as I know there is no other way around it.

 

even if you got rid of the flap and kept the sensor?

 

The sensor I think is just a resistor. The resistance value changes as the flap moves. Without the flap the sensor wouldn't work. I'm not positve here, but pretty damn sure.

 

Alright, thanks that makes sense now. Anyone else have any thoughts on this?

 

It may be possible, but I highly doubt it. If I were you, I wouldn't start disassembling/constructing anything unless you have an extra one lying around. If you break that, you'll be kicking yourself when Mazda charges you an arm, a leg, and most of your left ear for the new one.

 

definatley, i was gonna pick one up off ebay before i tried anything.

 

Your car will not run without your Air Flow Metering valve it is in the same circuit as your fuel pump. The flapper door opening during starting and for exceleration and RPM's operates your fuel pump. The door is open more during starting and cold conditions and closes until just bearly open at normal idle. The faster you go, the harder you stomp on the gas the more the door opens the more pressure/volume the fuel pump delivers. I found used AFM's on Carparts.com for very reasonable rates 45.00, hope this helps a little. Gary

 

A volume airflow sensor measures airflow, or air volume. The sensor consists of a spring loaded flap, potentiometer, damping chamber, backfire protection valve, and idle by-pass channel. As air is drawn into the engine, the flap is deflected against the spring. A potentiometer attached to the flap shaft monitors the flap movement and produces a corresponding voltage signal. The strength of the signal increases as the flap opens. Airflow sensors that only measure air volume must have their readings adjusted to account for differences in air temperature. This is done by air temperature sensor that is mounted in the induction system. The computer uses these 2 input signals to determine th e amount of oxygen entering the engine.

Mass airflow sensors do the same job as a volume airflow sensor and an air temperature sensor. It measures air mass hence the name. The mass airflow sensor converts air flowing pass a heated sensing element into an electronic signal. The strength of this signal is determined by the energy needed to keep the element at a constant temperature above the incoming ambient air temperature. As volume and density of airflow across the heated element changes, the temperature of the element is adjusted to maintain the desired temperature of the heating element. The computer monitors the changes in current to determine air mass and to calculate precise fuel requirements.