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Originally Posted by Max777
Well, I know that the trap door sensor is a bit different from a "hot wire" style MAF, and that this is used for fuel on the stock ECU.
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Yes, two different ways of doing this same thing.
They both measure "mass air", or the amount of air flowing into the intake / engine.
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so what's different between a pressure sensor and a MAP sensor? I thought that these were the same thing, no? And if you cant have both, then why does this car have both systems?
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Good question...
IN GENERAL:
A "pressure sensor" can only see pressure or positive pressure relative to "0 atmospheric (pressure).
A "MAP sensor" (remember, "MAP" stands for "manifold absolute pressure") senses both pressure *and* vacuum.
The "absolute" part means it ignores "relative to 0 atmospheric (pressure)".
What this means is that MAP sensors start at "absolute vacuum" or very near that level - this is it's zero point.
(Absolute vacuum is considered 30.0inHg or "-14.7psi" - most people don't like seeing "-" and "psi", but it's easier to explain this way.)
At sea level or "0 atmospheric pressure", a MAP sensor will actually "see" ~14.7psi.
http://wiki.xtronics.com/index.php/P...nversion_Table
Now, in the FC's case, Mazda does call the non-turbo FC's pressure sensor a...well, "pressure sensor".
The turbo FC's pressure sensor is called a "boost sensor".
That just confuses the whole issue. :P
This the learned, the non-turbo FC pressure sensor is actually a "1-bar MAP sensor" (reads vacuum up to "0" atmosphere); the turbo FC pressure is actually a "2-bar MAP sensor" (reads vacuum up to ~15psi of boost).
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I mean, a "pressure sensor" is fundamentaly the same thing as a MAP sensor, they both sense pressure, or am I totally missing something?
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Yes, in a sense.
I hope the above clears things up.
-Ted