FI Guru's, MAF sensor Options

[r_towle]

Hi,
What does a generic Mass Air Flow sensor measure?

Does it measure volume? velocity? pressure?

And, is there a generic one that could be read via a serial cable to a laptop?
A kit is cool, or a homemade version is also fine.

Rich

[banger]

Actually it does what the name implies... It measures the MASS of the air flowing. They are pretty simple devices. If you buy a Ford MAF, you connect it to 12V and Gnd, and it will output an analog voltage proportional to the amount of air flowing through it. It is fairly linear, and there are charts on the web that will tell you how much air corresponds to a given voltage output. If you have a multimeter, you can measure the voltage, then look it up on the chart and see the amount of air. Ideally you would want to find one that is from a car with similar horsepower to the one that you will be putting it on. Otherwise you will decrease your resolution if you get one to big, or run out of resolution if you get one too small. The principals of them are pretty simple. The old VW ones basically had a flap that would move in response to the airflow. Most modern sensors are the heated wire type. They use 12V to heat a wire to a specific temperature, as airflow increases, the wire cools, and they have to add more power to keep the wire at that temp. They measure how much additional power is needed, and this gives you the reading for airflow.