Date:         Thu, 10 Apr 2003 07:34:13 -0700
Reply-To:     laurasdog@WEIRDSTUFFWEMAKE.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Steve Delanty <laurasdog@WEIRDSTUFFWEMAKE.COM>
Subject:      Re: Vanagon Syndrome
In-Reply-To:  <2785FB32.0F9A4A34.0000D61A@aol.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed

>I have lived in denial for three years.  This is what happens, after about
>1 - 2 hours of driving, the darn thing would just quit on me (like its out
>of gas or lost its spark).

Uh huh...

>After replacing all these parts and still fighting with the darling
>beastie, I discovered this list and have spent a couple of hours reading
>the "Vanagon Syndrome" archives and found two promising fixes; a new
>wiring harness for the air sensor and a capacitor installation.

I have the fancy wiring harness. I also added the AFM capacitor. In my case it
didn't help.

>Can anyone tell me what size capacitor and where and how to install it?  I
>assume I can get the wiring harness from a parts store or dealer.

Here's the scoop on the capacitor:
http://www.geocities.com/harald_nancy/intermitt._syndrome.htm

The capacitor allegedly does the same thing as the harness.
The capacitor will cost under $2. The harness will most assuredly
cost more. Try the capacitor first. Neither helped me.
-----------

I'm certainly not a digifant expert, and I've only owned a vanagon
a couple months, but I'm not a stranger to electrical troubleshooting
and based on a bunch of hours with a scope and VOM peering into
the engine hole, and from what I've read on the web, here's MY
OPINION about vanagon syndrome.... FWIW

I think that "vanagon syndrome" can be caused by a wide range
of things, all of which confuse the AFM until it blows it's mind.
A quick key-off reset clears it's mind and all is well... until next time.

It's also my opinion, from all I've read on the web, and from my
own testing that a large percentage of the time this is caused
by flaky electrical connections and especially by insufficient
grounding. Many folks have apparently fixed their problem by
finding and repairing a missing/broken/loose/corroded ground
connection. The 2 flat ground braids, one on the left side head
and one on the nose of the tranny are the 2 major ground points
between the engine and body and MUST be clean, tight, and in
good condition.

Check these items FIRST, before you spend money and time
replacing parts !!!

In *most* cases, random replacing of parts; O2 sensor, AFM,
fuel filter, etc. doesn't seem to help except to lighten the wallet.

Unfortunately, the stock grounding mat be barely adequate at best.
I did some careful measuring with an oscilloscope and found an
amazing amount of voltage measured between the engine block
and the body. When the alternator is charging at moderate current,
there was over 1/4 volt of DC voltage between engine and body and
another 1/4+ volt of 3-phase alternator noise riding on top of the DC
voltage.

Since the O2 sensor output voltage is only around 1/2 volt, it's not
hard to see how a 1/2 a volt of DC offset and AC noise on the engine
ground would screw the ECU bigtime...

The fact that these noise voltages increase with increased alternator
output explains why some folks find that vanagon syndrome gets
worse when lights, cooling fans, AC, etc are on.

So. After my findings with the oscilloscope on the engine ground I
did 2 things. First, I added a noise supression capacitor on the
back of the alternator. This capacitor is stock equipment, but they
have a tendency to disappear with time, as people forget to put
them back on during an alternator replacement. Mine was missing.

I don't know the value for the stock capacitor, but I used 0.5 uF
250 volt ceramic disc capacitor on mine. Or you can goto the
FLAPS and buy one for almost any make and model of car
and it should work fine. Even the condenser from a points type
distributor will work good. These are typically 0.25 - 0.5 uF at
a couple hundred volts.

The capacitor connects from the + output stud on the back of
the alternator to one of the ground studs on the alt.

Whatever else you do, if your alternator is missing this capacitor
GET ONE!  I was rather surprised at how much it reduced the
electrical noise resident on both the engine ground and on the +12
volt line. It's the first line of defense for providing a clean noise free
environment for the ECU. I think it is VERY important.

The second thing I did was to add a #2AWG wire directly from
the back of the alternator to the body at the front of the engine
compartment,  well away from the stock ground points on the
left side. This gives the alternator charging current a nice direct
path to the body of the vehicle and reduces the current thru the
stock ground braids, which helps reduce the DC voltage drop
problem I was seeing across the stock flat braid.

These 2 "fixes" reduced the electrical noise by a factor of about
10:1 and has made my wasserboxer run noticeably smoother,
and I believe it has also cured my vanagon syndrome.

Since the price of 2 feet of #2 wire and some fat crimp lugs for
the ends is only a few bucks, and the alternator capacitor is
probably a few bucks from the FLAPS or less from a wrecking
yard, I think it's probably a worthwhile shot for most syndrome
sufferers to try. What else can you do to a vanagon for under $20 ?

Sorry for the length of this, but I'm hoping it might help some VS
sufferers out there.

Please keep me informed of any results, good or bad from
trying these 2 things.

Happy motoring,
Steve