Airflow meter discussion

[Ludis Langens]

Jon Snoddy wrote:
> 
> Isn't that what a map sensor is (two sensors that measure pressure on either
> side of the throttle)?  Assuming there isn't a meaningful pressure drop
> across air filter (or at least that it is linear), it measures the delta
> between the manifold pressure and atmospheric?

Nope.  MAP = Manifold ABSOLUTE Pressure.  One sensor on the manifold
side of the throttle.  It measures absolute pressure - or, pressure
relative to a complete vacuum.  Atmospheric pressure isn't measured, at
least not directly.  Some/many systems use the MAP sensor to sample the
atmospheric pressure before the engine starts.

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
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