3 Bar Map Sensor, What for???

Discussion in 'Fox 5.0 Mustang Tech' started by somersdp, Dec 20, 2003.

  1. I have read about people getting a 3 bar map sensor, so what is the purpose of that? I dont really understand and where are they getting them. I have never seen one advertised. Im sure there is more people wondering but nobody has ever asked on the forums before. Thanks for the help guys.
  2. I have no idea what a 3 bar map sensor is. If I had speed density I'd just convert to mass air rather than try to upgrade it.

    Now that I think about it.... I think what they're talking about is the German way of measuring pressure. It is measured in bars. One bar is like 7 PSI. So I guess that would mean they have a 21PSI MAP sensor?????? Just my guess.
  3. I'm not very knowledgable in this area, but I do know they're used in boosted situations. Just going by the name of MAP (manifold absolute pressure) sensor, my guess is that a stock sensor will not register beyond atmospheric pressure, which is 1 bar absolute pressure (0 psig). As soon as you run boost (over 14.7psia) you'll need a 3 bar sensor. Which by my understanding, should read up to 44.1psia or 29.4psig.

    Of course, I could be way off cuz I'm just guessing here...
  4. That sound right to me. I know that all the featured cars that are in mm&ff that are running any boost usally have a 3 bar. Thanks guys.
  5. It's used on aftermarket fuel injection setups. I have one on my ignition , but it's only used to retard the timing under boost.

  6. On a speed density system, the map sensor is connected to the manifold to measure vacuum and send that signal to the computer. On a mass air car, the same sensor is left disconnected from the manifold, and thus measures atmospheric pressure. Occasionally people will get confused and either leave it disconnected from the manifold on a SD set up, or connect it to vacuum on a mass air set up -- either way, it really screws things up.

    How all that connects with the notion of a 3-bar map sensor I don't know - so this post will let me follow along to learn something.

    My car has a 5-bar oil pressure gauge and sender allowing it to measure up to 75 psi. The other poster gave the correct correlation of what a bar is - one atmosphere (14.7 psia) at standard temps.
  7. go on turbomustangs.com and search, the topic has been discussed there many times.
  8. Thanks guys, I know this doesnt apply to everone but I know I still want to be informed as much as possible, ya know.