Date: Mon, 16 Nov 1998 17:36:10 -0800
Reply-To: David Thompson <David.Thompson@EDWARDS.AF.MIL>
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: David Thompson <David.Thompson@EDWARDS.AF.MIL>
Subject: Re: Having an annoying problem with my 85 GL.
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I have an intermittant problem similar tothe one described below. With (of course) a twist... With no consistent operating conditions (outsite temp etc.). My Van will fade from a chipper cruise at highway speeds (4000 rpm) to a weak 2800 rpm (or so), until I turn the ignition key off and immediately restart the motor. The van will then either do the same thing again instantly, in 5 minutes, or in 5000 miles. Of course it never manifests when I take it to a mechanic, except once: It started to do it consistently and the O2 sensor tested bad so it was replaced. It worked for awhile but then the problem came back. I was then sad.
Is there any way I can tell if it's the cat?
What soleniod is the writer below referring to? Is there a way that I can tell if this item is the problem?
Any other suggestions? I have to assume this is a common problem because the same thing happened with my old '86 Syncro Westfalia. The car was totalled, so it became a non-issue in that case.... I'd hate to have to resort to this fix again!
David Thompson
david.thompson@edwards.af.mil
1990 Syncro Westfalia
>>> "Mark A. Williamson" <mwilliamson@ABCH2O.COM> 11/16 1:55 PM >>>
I once experienced something similar with my 88 Wolfsburg Weekender. For
me, it turned out that the catalytic converter has become "clogged" due to
inadequate combustion of fuel. This led to the inability of the cylinders
to vent properly after the combustion cycle and the on-board computer sensed
a pressure high enough to make it think that the cylinders were "full" and
no fuel was injected for the next combustion cycle. The engine would not
completely stall however, because the next cycle fuel WOULD be injected and
combust- to a point. When, ultimately, back pressure could not be vented
adequately the engine "died." I replaced the catalytic converter and the
problem was gone and has not returned.
The fouled catalytic was (apparently) caused by a solenoid that crapped out
(intermittently), leading to unburned fuel gunking up the catalytic
converter. The ignition problem was corrected shortly before the catalytic
converter problem arose, as I though that the ignition system concern would
cure the "total" problem. It turned out to be only half the problem.
Summary/Suggestion(s): Check that fire is being delivered to the spark
plugs (correct frequency/timing and voltage). If correct, the back-pressure
may be building up and causing the "brain" to think the cylinders are full
of fuel. Then, the catalytic converter may be fouled. I am not sure if
simply check the compression on a cylinder will clarify this potential
condition, as the compression test will not distinguish between fuel and
burnt fuel.
Mark Williamson
Denver, CO
88 Wolfsburg Weekender
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