Effectiveness of RAM induction? (AFM replacement)

[Bruce]

Before getting too warm and comfortable, you might look at an editor for a
MAF type system and see what your facing.  If you  were to look around you
probably could find a freeware editor for like a GM ID mask 6E calibration,
and then see how they handle the airflow in the calibration.   While the MAF
system sounds like heaven atta glance, you might really consider using a MAP
/ RPM strategy, to get your MAF reading.  If you really want to min the
restriction, then why not go all the way?.
  Just thinking aloud
Bruce






----- Original Message -----
From: "Diehl, Jeffrey" <jdiehl at sandia.gov>
To: "'Phil Hunter '" <ilphayunterhay at yahoo.com>; <diy_efi at diy-efi.org>
Sent: Saturday, October 13, 2001 1:46 AM
Subject: RE: Effectiveness of RAM induction? (AFM replacement)


> I was going to suggest much the same thing. I intend to run the two at the
> same time on the car.  And build a tunable circuit to make the MAP look
like
> the AFM while I'm in the car.  That is, if the MAP outputs a
frequency-based
> signal, I'll convert it to voltage.  Then I'll adjust the scale with an
> op-amp.  Then I'll have to plot volt v. rpm to see what kind of
> (non)linearity I have.  I believe chips exist which will do log and
exponent
> functions on analog signals.  I'll bet they can be tuned to produce
> different functions.  When the MAP looks like the AFM, the AFM is GONE!
>
> Hey, talk is cheep, but this is what I'm thinking anyway.
>
> Comments?
>
> Mike Diehl.
>
> -----Original Message-----
> From: Phil Hunter
> To: diy_efi at diy-efi.org
> Sent: 10/12/2001 11:33 PM
> Subject: Re: Effectiveness of RAM induction? (AFM replacement)
>
> Mark Agnello wrote:
> >
> > > Now here is what I'm planning to do...
> > > From the TB, I'll go through a hot-wire MAP.  I'll
> > > have to build a circuit
> > > to make the MAP look like the AFM for the ECU.
> >
> > Jeffrey,
> >
> > I am interested in doing something similar.  I have
> > an All Trac Turbo. Same 3SGTE engine, similar
> > restricted intake path.  Have you put any serious
> > effort into figuring out how to emulate the AFM with
> > a hot wire MAF? I have a spare AFM and I have been
> > trying to figure out how to build a calibrated test
> > bench that will allow measuring voltage vs airflow
> > characteristics of the stock AFM.  Any ideas?
>
> Here's what I'd do: forget the test bench, put a GM 3"
> MAF in line w/ the AFM on the car so the same air has
> to flow through both, the Grams/Second vs. frequency
> out of the MAF has been posted recently so that's your
> calibration, use something like a PIC micro to read
> both the MAF frequency and the AFM voltage(s) for
> datalogging, for the adapter have the PIC drive a D/A
> convertor into the ECM, you can test your adapter by
> measuring the voltage difference against the AFM while
> it and the MAF are both are still in the car.
>
> You might look back at what I proposed to adapt the
> DIY-WB to a NB input, since this is essentially the
> same circuit idea.
>
> phil
>
>
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