Date:         Fri, 5 Mar 2010 11:02:43 -0600
Reply-To:     Tom Hargrave <thargrav@HIWAAY.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Tom Hargrave <thargrav@HIWAAY.NET>
Subject:      Re: AIR FLOW METER
Comments: To: Loren Busch <starwagen@GMAIL.COM>
In-Reply-To:  <86476e251003050843g368a823jca11f9b772dc33b@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"

Hot wire works by passing a constant current through a tungsten wire then measuring the resistance. More airflow = more cooling = cooler wire = less resistance across the wire.

The key to having something like this work is to start with a map of the old AFM system (CFM = resistance) and a map of the hotwire system (CFM - resistance or voltage drop). Then you would build a controller that would take the hot wire measurements & supply the correct corresponding resistance to the old system.

Thanks, 
Tom Hargrave
256-656-1924

Our Web Sites:
www.kegkits.com
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www.andyshotsauce.com


-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of Loren Busch
Sent: Friday, March 05, 2010 10:43 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: AIR FLOW METER

On Fri, Mar 5, 2010 at 8:17 AM, pdooley <psdooley@verizon.net> wrote:

> Somebody should come up with a MAF interpolator for this vehicle.
>

I assume you are talking about what some have called a 'hot wire' setup
rather than the moving vane.  At least two people or groups have
experimented with that idea that I'm aware of.  And ran into some problems
that are or would be difficult to get around, nonlinearities in making such
work with the existing Vanagon engine control system. Both of the attempts
that I'm aware of seem to have come to a halt, heard nothing for several
years now.
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