Date:         Sat, 4 Nov 2006 13:06:33 -0500
Reply-To:     Geza Polony <gezapolony@SBCGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Geza Polony <gezapolony@SBCGLOBAL.NET>
Subject:      Re: AFM Voltage Ratios

This is a question I've been asking for a long time, both here and on
westfalia.org, and no one seems to know. You're right, there must be SOME
concrete relationship between manifold pressure and AFM output voltage, but
no one seems to know what it is. The Bentley doesn't help, either. I took
mine off and measured the voltage using a hair dryer to simulate the air
flow, but that doesn't really tell you anything except that the voltage does
change, and pretty much evenly.

Without knowing what the voltage should be for a given set of AFM
conditions, it's impossible to calibrate the AFM. And you can bet that, with
most of these AFM's having 20-odd years on them, the voltage output "ain't
what it used to be." That would mean that at some point in the scale of air
flow, the engines are running too rich or too lean.

Unless there's something we're not getting. Why wouldn't the voltage data be
available?

??

Geza

On Fri, 3 Nov 2006 18:22:51 -0800, jon <jon@KENNEKE.COM> wrote:

>Does anyone have data on AFM voltage (out of the resistive divider) versus
>manifold pressure? I would think they would directly correlate in some
>linear fashion.
>
>Yes, I think of these types of things on a Friday night. ;)
>
>Jon