Scanner problems

[Scot Sealander]

Jason Weir wrote:

> Oh yeah and another thing, the scanner reads 10 hg at idle but a 
> vacuum gauge at the map sensor reads 18? again am I missing something 
> here? 

They are both reading right....  You have to keep in mind the reference
of both.  The scanner is reporting absolute pressure in the manifold, 
which is referenced from 0 inches of absolute pressure.  So the scanner 
value is 10 inches of mercury above 0.
 
The vacuum gauge is reporting reduced barometric pressure in the 
manifold.  That is, reduced from normal atmospheric pressure of about
30 inches of mercury.

Ideally the two values would add up to about 30.  You have 10 inches
and 18 inches, or about 28 inches total, a reasonable value.

Scot Sealander    Sealand at clarityconnect.com