Date: Thu, 16 May 2002 16:06:57 -0400
Reply-To: David Katsuki <dkatsuki@THEWORLD.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Katsuki <dkatsuki@THEWORLD.COM>
Subject: Re: Vanagon bogging - any possible diagnoses OTHER than the AFM?
In-Reply-To: <F266wMrNUaM14pKR16000000010@hotmail.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed
Chris,
This sounds like a classic example of the AFM wear problem. The problem
is that the pot connected to the AFM flap eventually wears through the
resistive substrate and starts to make an intermittent connection, which
causes the controller to get confused (hence fixed by cycling the ignition).
There are four well known cures (assuming that is the problem) which are
described in the archives:
The most expensive is to replace the AFM.
The next most expensive is to install the dealer-supplied upgrade harness
(part no 025 906 302), which has, I believe, a transformer and a capacitor
in it, and costs over $100.
The third is to add a capacitor (tantalum, bipolar, 22 mfd, 25 volt) across
two of the pins (either open the AFM case or add to the cable. I forget
what pin #s)
The fourth is to open the AFM case and clean the wiper contacts and then
realign the wiper or loosen the resistor substrate and move it so that the
wiper wipes a non-worn track.
All of these are described in the archives.
I don't think a bad engine ground (the one from the head to the body on the
drivers side) causes the hesitation symptom, but a piece of replacement 1"
ground strap should cost a couple of bucks, and you should probably replace
it any way if it looks corroded.
Dave
90 Westy
The At 03:14 PM 5/16/02 -0400, Chris Earl wrote:
>I have read all the archival correspondence regarding bogging, which has
>become a problem for my '87 Westfalia. After about an hour at highway
>speeds, it starts to lose power. This never happens below 50mph or on
>country roads where the velocity changes frequently, no matter how long I've
>been driving. The bogging can often be cured, albeit temporarily, by turning
>off the engine and turning it on again.
>
>Hoping to avoid costly replacement of the AFM, I am wondering what other
>things (fuel system, wiring and exhaust system have been suggested in the
>past) should be checked before springing for the new AFM and ground wire.
>
>Thanks!
>
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