Date:         Thu, 12 Aug 2010 11:51:55 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: AFM track cleaning wisdom
Comments: To: "Mike \"Rocket J Squirrel\"" <camping.elliott@GMAIL.COM>
In-Reply-To:  <4C63ECB1.7080904@gmail.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 08:44 AM 8/12/2010 Thursday, Mike \"Rocket J Squirrel\" wrote:
>Whaaaa..?
>
>Sez who?

The term "Vanagon Syndrome" has been rather corrupted.  The original
tech note from VW referred to a resonance effect under certain
conditions of steady throttle and load that could trigger an ECU
error mode.  The fix was an active circuit inserted into the AFM line
that limited maximum rate-of-change of the AFM signal.

This tech note was later extended to the 1.9l -- and indeed, I once
experienced the genuine article on a long straight road in Scotland
in '91, when my total mileage behind the wheel of a Vanagon was oh
say 500 or so.  It was in the '84 Westy that later became Dutiful
Passage.  A couple hundred miles earlier I'd experienced full-on 3-4
synchro hub failure, so you can see I was richly blessed.  And so I
was, with a sister (the then owner) who paid three thousand Scottish
pounds at the dealer for a transmission swap.

After a while VW quit giving out the little harness for free and
started charging serious money for it, and some bright spark thought
"I bet a few microfarads in the right place would do the job just as
well," and so it was.

But the law of unintended consequences came into play -- since either
device limited maximum rate of change of the signal, it would largely
cover up for little dropouts caused by track wear in the AFM.  For
once this was a good thing.

Thus saith the Lord.

Yours,
David