More silly ideas-MAP2

[Matt S Bower]

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