Date: Mon, 1 Jun 1998 09:29:40 -0600
Reply-To: Fred Porter <fporter@EYRING.COM>
Sender: Vanagon Mailing List <Vanagon@vanagon.com>
From: Fred Porter <fporter@EYRING.COM>
Organization: EYRING, Corp.
Subject: Re: van running rich- running out of ideas to fix
Content-Type: text/plain; charset=us-ascii
Bill,
Is there soot coming out of the tail pipe, otherwise, the lack of power
could be caused elsewhere.
have you tried adjusting the mixture via the AFM? Put your multimeter
back on the OXS, pop the cover off the afm and then open and close it
little bits at a time. If all else is working properly, you should see
a response from the OXS as the ECU commands different mixtures in
response to the different AFM outputs you have set
I did this once on my afm (using Dan Houg's procedure) and found i had
to increase the spring tension 2 clicks, otherwise the flapper was
openening to much and causing a rich running engine. the response from
the AFM is pretty sensitive. Have you read the Bosch bible? It shows
that best HP is achieved with a slightly rich setting. But yours sounds
way to rich. If it is this rich, your OXS may be getting clobbered
really quickly. Adjusting to run right at stoich is difficult and if
the mixture goes ever so slightly lean, NOx content of the exhaust after
the converter goes way up.
later,
fred
William Dummitt wrote:
>
> For a couple of months now, I have been trying to troubleshoot an 87 syncro
> that persists in running rich. It always starts right up, but will die if
> left idling as the mixture gets richer. It can be driven (sort of) but
> usually dies at stop lights (always restarts) and has little power-hard to
> get above 50 mph or so. I've spent many hours on it, so has my local
> independent vw mechanic (he's not bad, but doesn't see many late-model
> vanagons). I have a good-running 87 van to swap parts from, but I STILL
> can't diagnose this problem. When I bought it it wasn't running
> particularly well, but I was confident that I could fix it. At the time it
> had the cat converter replaced with a straight pipe, no oxygen sensor. It
> also had a bad afm. I installed a converter and oxygen sensor and a good
> afm ( works fine if I swap it into another van) , but it still runs poorly.
> Here are the other things I've done:
>
> Checked fuel pressure (30 psi), swapped fpr to be sure.
> All voltmeter/ohmeter checks at the ecu connector per Bentley OK.
> Cleaned ecu connections, checked and cleaned all grounds, replaced ground
> strap from left head.
> New plugs, wires, cap, rotor, installed afm harness upgrade.
> Replaced temp sensor II- checks out OK with ohmeter.
> Swapped from good-running van: ecu, afm, coil, idle control valve.
> Emptied contents of converter to make sure it wasn't clogged.
> None of the above new parts or swaps had any effect on performance.
> A voltmeter on the oxygen sensor shows predominantly 0.8-0.9 v. with the
> usual fluctuations, so the sensor is definitely trying to tell the ecu that
> it is too rich. Disconnecting the oxygen sensor has no effect on the way
> it runs that I can discern. I'm starting to be suspicious of the main
> wiring harness but replacing that on the syncro will be a major
> job-probably will require dropping the gas tank and tranny.
>
> The engine is not in great health, but I don't think it's bad enough to
> blame for the poor performance. Compression is 135-135-90-120. Head
> gaskets had apparently been replaced (but not heads) by a real schlock
> mechanic-when I got it the ground from ecu to engine was disconnected, and
> the protective covers over the pushrod tubes were missing.
>
> I've gotten lots of advice from people on the list already, special thanks
> to Darrell Boehler and Kyle Wade, but I'm still stuck. Any ideas are very
> much appreciated.
>
> Bill
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