Date: Tue, 5 Oct 2004 09:19:06 -0400
Reply-To: Matt Sutton <msutts@EARTHLINK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Matt Sutton <msutts@EARTHLINK.NET>
Subject: Re: Update- rocky results, etc.
Content-type: text/plain; charset="US-ASCII"
Hi Joy,
First off, sorry to hear about the persistent problem. I think I know
what it feels like, though when I went through this I wasn't thousand of
miles from home.
Symptom-wise I had pretty much what you are describing: van starts, runs
for a while, but after warming up starts losing power, bucking, black smoke,
horrible over rich smell. Couldn't figure it out myself, and brought it to
well-meaning mechanics. Over almost a 4 week period, many fuel injection
parts were replaced: O2 sensor, AFM, Temp sender, Hall sender in the
distributor, and eventually even the ECU. All to no avail, and boy was it
expensive.
In my case, it turned out to be the wire that actually goes from the O2
sensor to the ECU, carrying the signal that tells the computer what's going
on. That wire (green, on the left hand side of the engine bay) is a coaxial
cable, like the ones used to go between stereo components: Shielded/grounded
on the outside to protect from interference, with the signal carried on the
inside. If there is any short, connectivity, inductance, whatever, between
the two- as there was in mine- the ECU pretty much loses it's mind and
doesn't know how to proceed. In the end I replaced over a thousand dollars
of parts for a problem that could've been fixed in an hour by someone who
knew where to look.
I don't really blame the mechanics on this- they weren't VW people, and
the Bentley wiring diagrams only hint about the nature of that cable. I've
definitely made any shop interactions I've had since a full time
collaboration, though.
About the Fuel Pump/ Pressure issue: From what I understand, the only
job the pump has is delivering a constant flow of adequate volume; so if the
pressure is too high, the pump is doing it's job fine. The fuel pressure
regulator may be bad, though- any excess pressure should be routed back to
the fuel tank on the return line. The regulator is a $60 part, but it is
testable while in the engine, I think. It is in the center of the engine
bay, just forward of the distributor, with 3 fuel lines and one vacuum hose
attached.
Good luck Joy,
-Matt Sutton
Brooklyn NY
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