MAF vs MAP

[Bruce Plecan]

-----Original Message-----
From: Chris Conlon <synchris at ricochet.net>
To: 'diy_efi at efi332.eng.ohio-state.edu' <diy_efi at efi332.eng.ohio-state.edu>
Date: Monday, September 14, 1998 2:38 AM
Subject: RE: MAF vs MAP


>Dr. Bruce wrote:
>> > Other than the reduced flow restriction of a MAP over a MAF are there
other advantages??
>>
>> MAF has the "disadvantage" of having the delay of the hot wire
>> to change temperature.
>> MAP can be slight more accurate during transistions, because of the
above.
>> ...
>> Either of the following can be true
>>   A properly tuned MAF is better than a poorly tuned MAP
>>   A properly tuned MAP is better than a poorly tuned MAF
>
>I agree with this, especially with the last part. My additional few cents:
>
>MAP sensors can have very fast response times, this can be a good thing
>but only if you have your filtering in order, which may be tricky.
>
>MAP sensors may have better dynamic range (again, if the filtering is
>right), but may *need* better dynamic range and finer map resolution.

Well, I'd really been stuck on that, till lately when I was sitting around
with my CSH on, and it was explained to me, that some ecm use
steps at the cut offs, whereas gm does interpolations, so the table
size isn't as critical as one might expect.  Nother interesting note
the High rent FP demo only show a spark 17x16 or some such,
and one would think that for that money if there was to be a notable
gain they would have used it.  And that was on a 3 bar MAP
application............

>For instance if you want a wild-cam MAP'ed engine to idle well, your
>map had better provide fine resolution at low vaccum and low RPMs.

In the tune up notes, I mention using a "custom" pintle to get a good
idle with a MAP.

>My *guess* is a MAP'ed engine could run better than a MAF engine
>on the low end *and* on the high end, but *only* if the A/F map has
>enough resolution in all the right places. (I don't think most do.)
>Otherwise the simplicity of measuring the mass flow more or less
>directly will win out; a much coarser map can be used and you'll still
>get decent results.
>
>My $0.02, apply salt before consuming.

Naa, Doc says salt free diet for me.  ugh..
Cheers
Bruce
>
>   Chris C.
>