Date: Thu, 19 Aug 2010 09:50:25 -0400
Reply-To: "A. Hurley" <ahurley@SHOPVIEWIT.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "A. Hurley" <ahurley@SHOPVIEWIT.COM>
Subject: Re: AFM track cleaning wisdom
In-Reply-To: <BLU0-SMTP15A497AE4ADAEB31B1EE1BA6970@phx.gbl>
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
I've been reading up on this - preparing to up the big grade to
Lewiston today.
I went over the engine last night and noticed the lid to the AFM on my
85 Vanagon just came right off, revealing the wiper blade, etc.
It's a pretty new 2.1 engine in the 85 Vanagon.
Andree
On Wed, 11
Aug 2010, Karl Wolz wrote:
> IIRC, you have an '85? I was told that the capacitor fix only worked on the
> digifant system, so if you have the original digijet 1.9L, the capacitor fix
> will do you no good. My engine used to cut out just as you're describing,
> especially after a long high speed run or after a stiff limb (or during).
> Quite aggravating. We never did find the reason for the cutting out, but it
> is well chronicled at VW dealerships, though most have probably forgotten
> the issue by now.
>
> One dealership mechanic was convinced that the problem (which occurred while
> the van was still under warranty) was poor grounding; he installed one
> ground strap after another, to no avail. We replace the ECU, the AFM,
> countless ground straps and other electronic parts. Eventually, we replaced
> the entire engine and the problem went away. No one was ever able to
> adequately diagnose the issue.
>
> Oh yeah, we did clean the wiper track in the AFM - no joy there either.
>
> Sorry,
>
> Karl Wolz
>
> |-----Original Message-----
> |From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> |Mike "Rocket J Squirrel"
> |Sent: Wednesday, August 11, 2010 3:59 PM
> |To: vanagon@GERRY.VANAGON.COM
> |Subject: Re: AFM track cleaning wisdom
> |
> |As I mentioned, I had the thing open a few years ago and moved the wiper
> |to a fresh portion of the track. I did this as you describe: by ovaling
> |the mounting holes, so I phrased it wrong, I didn't move the wiper but
> |the track. My bad.
> |
> |I've only put about 15,000 miles on the thing since, I doubt the wiper
> |has worn through the new portion of the track yet. But I will inspect
> |and report.
> |
> |I'm following up on the mechanic's suggestion as he felt that the
> |symptoms I described last week (see "Mystery engine cutouts") may be due
> |to a bit of schmutz on the track.
> |
> |Anyway, in Ye Olde Days when I was a broadcast engineer, we used to
> |clean the Shallco program attenuators (coined-silver contacts) with
> |Hoppe's gun oil. That's probably a bit gummy for a AFM potentiometer,
> |but there may be some other cleaner/preservative I can put on the track
> |while I have it open.
> |
> |Mike S and David-The-B both point out that abrading the track with a
> |pencil eraser is dumb, dumb, dumb. Point taken. See their posts for
> |details.
> |
> |To David, thanks for mentioning that capacitor -- yes, I have a 22uF
> |tant cap wired in to reduce wiper/track noise.
> |
> |Just for the record, Richard-K asks for general AFM track servicing
> |information and says that he has "some `bogging' problems similar to"
> |me. I want to say to Richard that I would not describe the problem I had
> |as "bogging," more like an abrupt loss of power, mixture slamming toward
> |full lean condition, ignition continuing, then after 3 to 4 seconds,
> |abrupt return of full power.
> |
> |Out of curiosity, does anyone know what the ECU tells the engine to do
> |if the AFM wiper loses contact with the track? Cut off fuel?
> |
> |--
> |Rocky J Squirrel
> |84 Westfalia: Mellow Yellow ("The Electrical Banana")
> |74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
> |Bend, OR
> |KG6RCR
> |
> |
> |
> |Tom Young wrote:
> |> As I recall, and I may be wrong, the issue here with the AFM track isn't
> |> that it's dirty, it's that hours and hours of wear and tear at a
> |> particular spot actually result in the surface material being etched
> |> away, causing the ECU to think "Oh, the AFM's vane is closed!" and
> |> reacting accordingly. So I'm not sure that cleaning has much to offer
> |> here.
> |>
> |> I've had good results by opening up the AFM (air-cooled, and I'm
> |> assuming the water-cooled engine's AFMs are the same), removing the 4
> |> screws that hold the wiper circuit board, removing the circuit board
> |> itself and then ovalizing the 4 holes in the board that the screws pass
> |> through. You can then re-install the circuit board in just a slightly
> |> different position, giving the wiper a new track to pass over.
> |>
> |> Tom Young
> |>
> |>
> |> ----- Original Message ----- From: "Mike "Rocket J Squirrel""
> |> <camping.elliott@GMAIL.COM>
> |> To: <vanagon@GERRY.VANAGON.COM>
> |> Sent: Wednesday, August 11, 2010 2:30 PM
> |> Subject: AFM track cleaning wisdom
> |>
> |>
> |>> My mechanic dude suggested the the cause of the engine's periodic but
> |>> brief loss of power during grade climbs last week might be a dirty spot
> |>> on the AFM track and suggested gently cleaning it with a pencil eraser.
> |>>
> |>> I opened it once before, a few years ago, to move the wiper to a fresh
> |>> bit of track. I'll open it again to clean the track.
> |>>
> |>> Is the pencil eraser trick good enough, or would it benefit to use some
> |>> kinda cleaner?
> |>>
> |>> --
> |>> Rocky J Squirrel
> |>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> |>> 74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
> |>> Bend, OR
> |>> KG6RCR
> |>>
> |>
>
Sincerely,
Andree Hurley
| 
