MAP Sensor

[Murphy, Ian]

Ideally your DIS should adjust advance according to the mass of the air
charge, in the same way that you need to adjust fuelling according to the
air charge. With a differential (gauge) sensor you could read the same value
of pressure for different combinations of throttle opening and atmospheric
pressure. But the density of the air charge and hence the required advance
would be different. Only an absolute sensor could tell the difference, or a
gauge sensor in combination with either a baro sensor or the throttle
position sensor.

What kind of system are you using and do you know what kind of strategy it
uses?

Ian

> -----Original Message-----
> From:	Mike Blakey [SMTP:mike.blakey at baesystems.com]
> Sent:	Wednesday, March 14, 2001 8:27 AM
> To:	diy_efi at diy-efi.org
> Subject:	RE: MAP Sensor
> 
> Thanks Ian,
> 
> If this is only being used for DIS, does a differential sensor not give a
> better 
> result due to the fact that as atmospheric pressure changes so will the
> ratio and 
> the advance accordingly?
> 
> 
> 
> 
> 
> Ian.Murphy at Arrows.com on 09/03/2001 13:17:43
> Please respond to diy_efi at diy-efi.org@INET2 at wtgw
> 
> To:	diy_efi at diy-efi.org@INET2 at wtgw
> cc:	 
> Paper Mail:	
> Subject:	RE: MAP Sensor
> 
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> 
> MAP stands for Manifold Absolute Pressure, so substituting a gauge
> (referenced to atmosphere) pressure is incorrect. MAP is often used to
> calculate charge density and hence fuelling using thermodynamic / fluid
> dynamics maths involving Ideal Gas laws.
> 
> Of course, if you include a Baro sensor when designing a system, you can
> infer MAP from a gauge sensor.
> 
> Ian
> 
> > -----Original Message-----
> > From:	Mike Blakey [SMTP:mike.blakey at baesystems.com]
> > Sent:	Friday, March 09, 2001 11:08 AM
> > To:	DIY_EFI at lists.diy-efi.org; efi332 at lists.diy-efi.org
> > Subject:	MAP Sensor
> > 
> > My company has changed my e-mail address so I've resent this post...
> > 
> > I have made my own MAP sensor from a differential bridge sensor (-1 to 0
> > bar). It 
> > works fine but I'm unsure of the expected range on a manifold, so far
> I've
> > only 
> > managed to get down to -780 mbar. If this is about typical I can alter
> the
> > gain and 
> > span to get better resolution over the expected range.  My sensor also
> is 
> > differential to atmospheric pressure, where as the OEM sensors do not
> seem
> > to be, 
> > is the correct?
> > 
> > 
> > 
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