Date: Thu, 6 Feb 2020 09:30:00 -0800
Reply-To: Neil N <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Neil N <musomuso@GMAIL.COM>
Subject: Re: Vanagon Syndrome/AFM Mounting Orientation?
In-Reply-To: <CACARJKrkeD9QkQ6DP9jUhGLy0PBRP6cHPyhM+Foi-69x+neJGQ@mail.gmail.com>
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> One thing different about my installation (I-4 swap) is that the AFM
> is mounted upside down (plastic cap down) relative to what I believe
> to be the normal orientation. Does anybody know if this could be the
> culprit?
I can't find the tech bulletin re: 'Vanagon syndrome' but IIRC, it
applied to Digifant, Digijet used on the WBX and Digifant on other
engines.
The AFM wiper arm et al likely weigh very little so I'd guess they
should work ok upside down but the metal vane, maybe not? Could it
bind or move poorly due to bearing surfaces not working as designed or
the vane itself is sticking to body at certain spots?
Tencentlife on the samba Vanagon forum shows how to measure an AFM for
voltage drop. Doing so would give a rough idea of the AFM voltage
range.
This page posted by a VW enthusiast who seems to know his stuff:
http://faculty.ccp.edu/faculty/dreed/Campingart/jettatech/maftesting.htm
suggests that the MAF under Motronic obd2 and obd2 generates
Idle .9 volts.
2000/3000 RPM 1.5 volts.
3000/Wide Open = up to 3.8 volts.
This, or similar, might be true of a MAF used under other engine
management systems.
I'd guess that even just the difference in voltage values between a
MAF and AFM would be an issue for trying to run a MAF in place of an
AFM.
..... I see a PDF on Split Second web page that, in part, talks about
voltage outputs:
https://splitsec.com/wp-content/uploads/technotes/TN2_AFM_to_MAF_Conversion.pdf
I'm curious how a MAF could be adapted to engine management that does
not have a TPS. To me, that alone would be a deal breaker.
Neil.
On 2/6/20, Alex MeVay <alex@mevay.org> wrote:
> Hi All,
>
> I had "Vanagon Syndrome" (bucking and uneven power delivery due to
> mixture problems from a failing air flow meter (AFM)). In 8/2018, I
> replaced the AFM with an offering from one of our favorite vendors,
> which was a rebuild by Fuel Injection Corporation of Tracy, CA, and
> had the magic capacitor added internally. Syndrome cured, for a time,
> but here I am just ~12k miles and 16 months later with the same
> symptoms returning.
>
> One thing different about my installation (I-4 swap) is that the AFM
> is mounted upside down (plastic cap down) relative to what I believe
> to be the normal orientation. Does anybody know if this could be the
> culprit? The original AFM had, I believe, lasted the PO a long time,
> but failed maybe 1-2 years after I changed the orientation. I also do
> a lot of off-road driving, so vibration could also be an issue.
>
> Any other ideas? If I have to re-do my intake to change the
> orientation of the AFM, I think I'd like to consider other options.
> Has anyone had luck running MAF conversions (e.g., the offering by
> Split Second) with Digifant II?
>
--
Neil n
VE7TBN
1988 Westy 50º ABA swap: https://tinyurl.com/yap5hpwt
1981 Westy 15º ABA swap: https://tinyurl.com/y9n4xob8
VAG Gas Engine Swap Group <http://tinyurl.com/khalbay>
