Date: Mon, 17 May 2021 11:34:26 -0700
Reply-To: Neil <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Neil <musomuso@GMAIL.COM>
Subject: Re: Crummy Vanagon performance
In-Reply-To: <CAB-k8XVaVmU=CXQv8T15N4v-YAN9QjEDU6eJrUzS8jO=7OOMfA@mail.gmail.com>
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Hi Gil.
"Cat" = catalytic converter.
I'm not saying a fault at O2 coax wire is the issue but presence of a
fluctuating voltage at O2 sensor may not rule out an intermittent
fault at coax wire on van. Easy to check that with VOM while slowly
flexing the end of that coax. It's also easy to do a visual inspection
of the coax. IF there's an intermittent fault there, the most common
failure point is near the end of coax where O2 sensor connects; the
inner wire shield breaks and stray strands of coax contact that
exposed point of inner wire.
The link you show is for Digifant pro training manual so, no. You want
"Digijet". I haven't verified the links but the .zip link here should
work:
https://www.thesamba.com/vw/forum/viewtopic.php?t=419312
Google should reveal other possible sources of that manual.
If this were my van, even though a lot of tests have been done, I'd go
through the pro training manual procedures in order to systematically
eliminate possible causes. At minimum, the manual provides useful
descriptions of parts involved which can be of use to the average
Vanagon owner.
Another caveat: I am by no means an expert or even a higher level
amateur, particularly on Digijet. That said......
In terms of a given part or parts not being designed for decades of
use, something "small" like a worn pivot point at switch arm inside a
throttle switch can be a source of a frustrating intermittent fault.
Given the years of service a Vanagon has been through and well
intended DIY work that may be done, something like the aux air
regulator and throttle switch connectors being inadvertently swapped
on the later model year 1.9 , can occur. (thanks to Dennis for that
tip).
First google search result for "Vanagon syndrome TSB vw"
https://www.thesamba.com/vw/forum/archive/index.php/o-t--t-682604--.html
I wasn't trying to lead you towards the AFM as being the fault. But.....
Though this is a test procedure for voltage dropout on the Digifant
(2.1 engine) AFM:
https://www.thesamba.com/vw/forum/viewtopic.php?t=369815
the 2.1 and 1.9 AFM pinout schemes are likely the same so the test
should work on the 1.9 AFM. That said, IMO, words like "should" and
"likely" should not apply to electrical work so a look at Digifant and
Digijet wiring diagrams should shed some light. In lieu of that AFM
test, open the AFM, use a magnifying glass to closely inspect the
resistive strip for excess wear.
If you see sloppy looking and or non OE looking silicone or adhesive
at the AFM cover, beware that someone else has been inside it. i.e.
who knows what they've done. e.g. some bend the wiper arm to place it
at a new patch of resistive material. That may or may not work.
Neil.
On 5/17/21, Gil Ngai <eyebawlgil@gmail.com> wrote:
> Neil here is a response form my mechanical friend Ron to your comments:
> The inner lead on green shielded O2 cable on vehicle harness may be
> shorting to cable shield.
>
> No. O2 sensor signal observed to be oscillating as expected.
>
>
> A failed and clogged cat might cause what you see.
>
> Catalytic Converter? (From Gil)
>
> Try to recreate the issue(s). Note if they *only* happen once the
> engine is warmed up.
>
>
> A PDF of the Digijet pro training manual can still be found online AFAIK.
>
> What's the best place to find this?Is this the right manual?
> http://cabby-info.com/Files/DigifantProTrainingManual.pdf (From Gil)
>
> I doubt Vanagon syndrome is the issue but to me, the VW TSB on VS
> indicates that VS can also happen in Digijet.
>
> Can you please email Technical Service Bulletin? Thanks!
--
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>
