More silly ideas-MAP2

[Peter Fenske]

Howday Terry and the rest of?

Baro is read via the Map sensor on key on no run
and at wot tps in run mode. There is a comparison done
against the previous Baro and if the reading is greater it
becomes the new baro.

Look in the AUJP code

:peter





"TK" <terryk at foothill.net> on 06/04/99 10:23:06 AM

Please respond to gmecm at efi332.eng.ohio-state.edu
                                                              
                                                              
                                                              
 To:      gmecm at efi332.eng.ohio-state.edu                     
                                                              
 cc:      (bcc: Peter Fenske/BCIT)                            
                                                              
                                                              
                                                              
 Subject: Re: More silly ideas-MAP2                           
                                                              








Seems to me I've seen code where the MAP is read at WOT for get a new Baro
reading. In fact doesn't the 747 have something in there about this?

Is this right Mr. Fenske?

Terry
-----Original Message-----
From: Matt S Bower <m.s.bower at cummins.com>
To: gmecm at efi332.eng.ohio-state.edu <gmecm at efi332.eng.ohio-state.edu>
Date: Friday, June 04, 1999 10:05 AM
Subject: Re: More silly ideas-MAP2


>
>
>Jeff M wrote:
>>
>> Bruce wrote:
>>
>> >In theory.  when you have Air Densities of 96% to 101% and the
>> >scanner shows the engine is at 98 K/Pa under both sets of conditions
then
>> >there is a fly in the ointment.
>>
>> MAP gives you pressure and BARO readings (one in the sensed same), and
>> density is calculated by adding air temperature computations via a MAT
>> sensor (aside from the changes humidity does to the equation, but no RH
>> sensors in GM vehicles yet ;-).
>>
>> To back up a bit, is not Barometric Pressure the measure of air pressure
>> relative to being at different altitudes and in varying climatic
conditions?
>> Then when the engine is exposed to these varying outside pressures, it
will
>> experience different cylinder filling (raw VE tables would not compensate
>> for this fully) while running.  And since warmer air is less dense (and
the
>> reverse as well), MAT needs to be added to the equation so (near) true
air
>> measuring can be performed.  So your fly has definitely landed but I
>> wonder if there is a need to compensate for this as it is already done on
>> better designed cars/computers.  MAP is used to measure barometric
readings
>> at start up  on many GM vehicles and as an example, the Syclone/Typhoon
use
>> the MAP to show on my scanner (Diacom Plus) Barometric Pressure, Manifold
>> Absolute Pressure and Boost Pressure, all supplied via the one MAP
sensor.
>> Maybe your program (vehicle?) does not do this BARO check and associated
>> compensation and if so then I would suggest extracting the computation
used
>> by the Sy/Tys (or others) to be incorporated into your vehicle's computer
>> program to get you what you want.
>
>I think you missed the point on this one.  He does have the baro check
>but he wants a way for it to continously read baro, not just at start
>up.  He wants to make the system more sensative, in a sense, to changes
>to be more accurate and try to make it self adjusting to changes is
>altitude or the such while he's at it.
>
>
> Another note on GM MAP sensors, they come
>> in many ranges depending on application (stay with me here) and not just
1
>> bar, 2 bar and 3 bar.  GM has found (as it gets it together) that the
>> reality of there being more than 1 bar of pressure at altitudes below see
>> level had a more dramatic effect on some vehicles than others so, GM has
1.1
>> and 1.2 and 1.25....... "1 bar" MAP sensors.
>>
>> More FYI:                                            multiply by
>> Bars to Atmospheres                           0.9869233
>> Bars to Inches Mercury                      29.529983
>> Bars to Inches of Water                    401.48716
>> Bars to Kilograms per sq centimeter     1.0197162
>> Bars to Kilopascals                           100.00 (exact)
>> Bars to Psi                                         14.503774
>>
>> >Weither do to filtering,  the design of the sensor, or pulsation
>> characteristics, that the >sensor is reading something is wrong.  Without
>> an emission lab to do the research >something needs done to compensate
for
>> it.   "My" baro/map idea isn't perfect, but it's a >whole lot better
than,
>> being in error all the time, IMHO.....
>> >Grumpy
>>
>> You are right about being better, and that is the challenge we all do
enjoy.
>>
>> Jeff Middaugh
>> tystorm at email.msn.com
>