Date:         Sat, 5 Jul 2014 15:15:01 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Update on AFM testing procedure
Comments: To: Neil N <musomuso@gmail.com>
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              mail.com>
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At 02:16 PM 7/5/2014, Neil N wrote:
>usually clean it when I replace the air filter. David's comment below
>makes me think that "yes", it burns off any oil during use. There is a
>protective mesh on this MAF.

The one that I read up on long ago would heat the filament to at
least red hot, possibly white hot for a short time at some point in
either startup or shutdown cycle, possibly both.  Being platinum it
was much more resistant to that sort of insult than to anything touching it.

In use it would maintain the wire at a specific temperature and
monitor how much current was required at that moment to do so.  That
would allow calculation of how much heat the wire was losing to the
flowing air and thus what mass of air was contacting the wire in each
measurement cycle.  And finally from that the mass flowing through
the intake.  I think maybe they kept the wire hot enough that
differences in intake air temperature were swamped - just short of
glowing tickles the back of my mind somehow.  What I'm not sure I
understood at the time and certainly don't remember now was how they
measured the temperature of the wire so they could control it.  I
have a bit of a feeling that it was something diabolically clever
that I thought would have to conflict with what else they were doing
with the wire,

The wire needs unobstructed airflow (and hence heat transfer) on its
surface and because it's so thin very small particles on the surface
can have considerable effect.  I think it really has to run squeaky
clean all the time.

Yrs,
d