Date: Sat, 26 Nov 2011 09:45:54 -0500
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: vanagon syndrome strikes...advice?
In-Reply-To: <1wag94rdpvts49u2kgie26vt.1322280437419@email.android.com>
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In my opinion "Vanagon Syndrome" is a myth. It always comes down to an O2 sensor or circuit problem. Capacitors and active harness gizmos may slightly max or hide it but the problem is not fixed until that O2 sensor issue is corrected.
One thing that never gets mentioned is the O2 sensor heater. You need to make sure it is working. You need to make sure that it is not open and that near 12 volts is there with it connected. I have seen wiring issues where the plug has 12 volts with the sensor disconnected but due to a bad wire in the harness it drops off once the sensor is plugged in.
The sensor is almost like a battery. It works via a chemical reaction. I have witnessed the sensor working fine most of the time and then during a long trip it begins to fail to produce voltage. Run away rich here we come (the Syndrome). Stop for a while and then it works OK and after some time "it's happening again".
The sensor placement is really in a bad location. It is not in a consistently hot part of the exhaust. It is exposed to a lot of cooling air. It's sprayed-contaminated with rain, salt, road dirt and everything else coming right off that left rear tire. What were they thinking? Then we add some poor wiring that corrodes and combine some grounds and it a wonder things work at all.
The only Vanagon uniqueness here is how often it plagues us.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of David Hardy
Sent: Friday, November 25, 2011 11:07 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: vanagon syndrome strikes...advice?
So a quick update...I unplugged the O2 sensor (thanks Angus) and the problem went away - so I changed out the sensor and she ran perfect all day. Maybe I had vanagon syndrome *and* bad O2 sensor...who knows...but we are back in happy camper-land.
Love this list...
David
Sent from my Android
John Meeks <vanagon@gmail.com> wrote:
>David,
>
>Sounds like you've done all the right stuff to eliminate Vanagon
>syndrome as the cause of your problems..
>The first thing I thought after reading your diagnostic process was a
>failing catalytic converter. Could cause those symptoms when the cat
>gets hot.
>
>You might also check your voltages at the ECU per Bentley manual.
>
>John Meeks
>'91 Vanagon MV
>Northern Michigan
>
>Vanagon Rescue Squad
>www.vanagonauts.com
>
>
>
>On Fri, Nov 25, 2011 at 10:14 AM, David Hardy <david@planetmind.net> wrote:
>
>> Long story short...left Colorado for New Mexico in my new-to-me 1990
>> westy Sunday, when 2 hrs into the trip on I-25 I felt the dreaded
>> single engine "buck" - one simple stumble, then another 20 minutes
>> later, then another in
>> 10 minutes...then every few minutes or so. By the time we got to
>> Trinidad, she was stumbling pretty badly , but not bad enough to
>> stall out. stumbling was *not* accompanied by tach needle drop, and
>> seemed to do it when pressing accellerator after letting off. if I
>> pushed the clutch in during an "episode", idle would be erratic,
>> surging and sometimes dropping slowly to stall. hard to say whether
>> turning ignition off/on made it go away, as condition was very intermittent.
>>
>> Next morning replaced fuel filter and put in some injector cleaner.
>> One hour later down the highway, same deal.
>>
>> Got to Taos, read up and went to Radio Shack for a 22mf capacitor and
>> a soldering iron. Also got a new cap and rotor and a set of spark
>> plugs just in case. Installed the capacitor (electrolytic, didn't
>> have a tantalum), and put in new cap and rotor. thought all was
>> well...until about 2 hrs down the road from Taos to Albuquerque,
>> syndrome returned but a little different...this time it was not
>> stumbling, but hesitation - like a flat spot. pressing accelerator to
>> floor seemed to make it "catch" and clear the condition, but it would return 2-5 min later.
>>
>> So I got back in and cleaned the resistive pad in the AFM w/alcohol,
>> and loosened the screws that hold it's mounting plate and shifted it
>> about 1/2mm to get the wiper on a new track. Ran perfect for about 30
>> minutes on highway, but then it struck again and this time it was
>> pretty severe hesitation - gas pedal wouldn't rev engine, no power, it would just cough.
>> if I let it go to idle it would stall. turning off ignition and on
>> again cleared it totally - for about 3 minutes.
>>
>> So I opened things up again and moved the plate back. installed new
>> plug wires for the heck of it. Also got a new O2 sensor, but couldn't
>> get the old one off. haven't had a chance to test it yet...kind of a
>> pain to have to drive an hour to see if something fixed it.
>>
>> So, anyone have any recommendations? Also, does anyone know where I
>> can get a replacement AFM in Albuquerque?
>>
>> David
>>
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> David Hardy
>> Planetmind Internetworks
>> Nedernet, Inc.
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
