Barometric pressure

[rr]

Actually they do a pretty good job of it. There is an SAE paper on the Delphi
site that covers the whole enchilada:

1999-01-0206
Barometric Pressure Estimator for Production
Engine Control and Diagnostics

Look through the 1999 papers list & you'll be able to download it. This link
should get you close:

http://www.delphiauto.com/index.cfm?location=655

BobR.


Programmer wrote:

> I can see a full time baro--but how would a regular MAP take a BARO shot at
> 75% throttle and be accurate ?
>
> Lyndon.
> ----- Original Message -----
> From: "Bruce" <nacelp at bright.net>
> To: <diy_efi at diy-efi.org>
> Sent: Thursday, September 14, 2000 8:09 AM
> Subject: Re: Barometric pressure
>
> >
> > There are several strategies.
> > Some take a glance at startup, then others at 3/4 throttle, do a review of
> > it
> > The earlier ones use a full time baro sensor.
> > (the above, reference GM)
> > Bruce
> >
> >
> > ----- Original Message -----
> > From: "Programmer" <nwester at eidnet.org>
> > To: <diy_efi at diy-efi.org>
> > Sent: Friday, September 14, 2001 10:04 AM
> > Subject: Re: Barometric pressure
> >
> >
> > > I never knew the Baro value changed...until next key on. One reason is
> > that
> > > you can start an EFI down here, drive to Banff--and it's running on the
> > rich
> > > side till you stop for gas <G>... suddenly, it's fixed. The 3000 ft
> > > elevation change isn't updated till next key on cycle. If they're using
> a
> > > WOT run for an update, I dunno--IMO it's not the whizziest idea in the
> > park.
> > >
> > > Lyndon.
> > > ----- Original Message -----
> > > From: "Jason Haines" <jhaines at lingenfelter.com>
> > > To: <diy_efi at diy-efi.org>
> > > Sent: Thursday, September 13, 2001 11:08 AM
> > > Subject: Re: Barometric pressure
> > >
> > >
> > > > On the newer GM vehicles, (such as the 1994 application originally
> asked
> > > > about) the MAP sensor is used to determine the barometric pressure. In
> > > > addition to setting the barometer to the MAP reading at key up, the
> MAP
> > > > readings are also compared to the stored barometer reading under
> > different
> > > > conditions (WOT being one of them) and changed based on the expected
> > > > pressure drop in the system at different RPM levels, throttle
> positions
> > > and
> > > > air flows (in MAF based systems). Different vehicles, ECMs etc. have
> > > > different levels of complexity of this model.  It is my understanding
> > that
> > > > one of the reasons for doing this form of barometric pressure
> updating,
> > in
> > > > addition to whatever issues the OE may have, is to comply with EPA and
> > > CARB
> > > > requirements for altitude compensation (manufacturers are no longer
> > > allowed
> > > > to have separate high altitude calibrations).
> > > >
> > > > Some appilications do use a separate barometric pressure sensor but
> this
> > > is
> > > > rare (I only know of one GM application).
> > > >
> > > > The above information applies to GM vehicles but should be true for
> many
> > > > other applications. They all want to save money on sensors so they try
> > to
> > > > reduce the content on the ECM and in the vehicle (plus, less parts
> means
> > > > less parts to go bad).
> > > >
> > > > Just my $0.02
> > > >
> > > > Jason
> > > >
> > > >
> > > > > As far as I know--it's only a snapshot at key on.
> > > > > I don't know how it'd do it at WOT...if exhaust was
> > > > > partially plugged, it'd really wonk the settings.
> > > > >
> > > > > Lyndon.
> > > > > ----- Original Message -----
> > > > > From: "terryk" <terryk at foothill.net>
> > > > > To: <diy_efi at diy-efi.org>
> > > > > Sent: Wednesday, September 12, 2001 7:00 PM
> > > > > Subject: Re: Barometric pressure
> > > > >
> > > > >
> > > > > > Correct me if I'm wrong, but doesn't some early code measure it at
> > > WOT?
> > > > > >
> > > > > > TK
> > > > > >
> > > > > > ----- Original Message -----
> > > > > > From: "Programmer" <nwester at eidnet.org>
> > > > > > To: <diy_efi at diy-efi.org>
> > > > > > Sent: Wednesday, September 12, 2001 5:17 PM
> > > > > > Subject: Re: Barometric pressure
> > > > > >
> > > > > >
> > > > > > > The MAP sensor (at key on).
> > > > > > >
> > > > > > > Lyndon.
> > > > > > > ----- Original Message -----
> > > > > > > From: "bob r johnson" <bobj_johnson at juno.com>
> > > > > > > To: <diy_efi at diy-efi.org>
> > > > > > > Sent: Wednesday, September 12, 2001 7:03 PM
> > > > > > > Subject: Barometric pressure
> > > > > > >
> > > > > > >
> > > > > > > > Could someone tell me, on a 94 Z28, what sensor measures
> > > barometric
> > > > > > > > pressure?
> > > > > > > > Thanks,
> > > > >
> > > >
> > >
> >
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