DIY_EFI Digest V5 #432

[Tom]

Newer Ford MAF's are not even close to being linear.. or easily modelled by
a single multi-ordered equation.

You can get an approximation of yours by using one of the Data Loggers
available for your DSM. (1g I assume since the 2g maf is good for 40 lb/min
or are you building a 10 sec car?) With an unmolested air meter, log the air
mass and compare that to the frequency of the meter. You can either use a
multimeter, S-AFC, MASC, or other gizmo to get the raw maf frequency signal.

Regarding the other thread.. There is no reason to vent the BOV to the
atmosphere. Don't be a riceboy.

-tom

> Date: Wed, 03 Jan 2001 22:06:07 -0500
> From: Rob O <rjo1 at home.com>
> Subject: Re: MAF transfer curves
>
> Anyone got charts for the KV flowmeters used on the Talon/Eclipse/Laser?
> I'd like to use something like the pro-flo 75MM bullet but need to do a
> voltage/frequency convertor and have no clue as to where to start on the
> conversion tables
>
> Rob_O
>
> "Shirley, Mark R" wrote:
> >
> > At least on the Ford MAF's I had transfer functions for,
> > they were all linear voltage 0-5V with a little rolloff on
> > both ends.  These were Hitachi parts.
> >
> > -----Original Message-----
> > From: Bruce Plecan [mailto:nacelp at bright.net]
> > Sent: Wednesday, January 03, 2001 9:55 AM
> > To: diy_efi at diy-efi.org
> > Subject: Re: MAF transfer curves
> >
> > Some are even frequency.
> > I wouldn't say anything universaily applies about MAFs
> > Bruce
> >
> > > Different transfer curves for MAFs?
> > > Is this true?? I was led to believe that voltage output was linear
> > > with respect to airflow for all makes. The only difference being
> > > the sizes and connectors used. I don't mean to question Chris but
> > > This would have some serious implications for my flapper-conversion
> > > project so I'm very curious.
> > > Thanks,
> > > Rod
> > >
> > >
> > >
> > >
> > >
> > > >Date: Sat, 30 Dec 2000 00:36:47 -0500
> > > >From: Chris Conlon <synchris at ricochet.net>
> > > >Subject: MAF transfer curves
> > >
> > > >I was wondering a bit about MAF transfer curves.
> > >
> > > >I seem to remember people mentioning that some MAFs (GM perhaps)
> > > >had a voltage output that was linear with respect to airflow.
> > >
> > > >In the archives I found that someone else, using a Bosch MAF,
> > > >found that airflow varied as the square of voltage. (Or, voltage
> > > >output varied as the square root of airflow.)
> > >
> > > >Looking at the curve for a random Pro-flow MAF
> > > ><http://www.pro-flow.com/24flow.htm>
> > > >it appears that airflow varies as the cube of the voltage. (If you
> > > >plot V vs the cube root of airflow, you get a straight line.) As
> > > >near as I can tell these units are intended for Ford applications.
> > >
> > > >I wonder what other transfer curves are out there? Are there any
> > > >logarithmic MAFs?
> > >
> > >    Chris C.

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