After all this does unplugging the O2 still fix the problem?
                                 Eric

Frank Condelli wrote:

>        OK, gurus I have a problem here that I have been unable to resolve
>and am asking your collective help.
>       1991 2.1 engined Vanagon.  Running way too rich, black smoke pouring
>out of exhaust tail pipe at idle and under acceleration.  At cold startup it
>seems to be running perfectly, no black smoke, when the engine warms up, you can
>hear it change rhythm, the black smoke starts pouring out the exhaust.  Let
>it sit until the engine goes back to cold and restart it will run perfectly
>until it warms up, drop in idle then black smoke again.
>       Unplugging the O2 sensor cures the problem, so I immediately though it
>was a bad O2 sensor.  I have done the following and NONE has resolved the
>issue.  New CAT, new OXY sensor (tried two), exhaust system is not leaking
>anywhere.  Checked & replaced Temp II sensor (original was giving same readings as
>the new one but replaced anyways). Checked throttle position switch, mechanical
>clicking and continuity test, OK.  Checked AFM, all readings as per Bentley,
>swapped in an AFM from a perfectly running 2.1, made no difference.  Checked
>air intake track, clear and free of obstructions.  Tried swapping computers,
>two different ones actually, all the same.  Checked all wiring from computer
>terminal plug to respective sensors, did all tests as per Bentley, all OK.
>Checked all grounds, all OK. Idle stabiliser valve humming, unplugging it will kill
>the engine, unplugging it by the yellow connector on the firewall drops the
>rpm.  Swapped in an Idle Stabiliser Control Unit from a known working 2.1, made
>no difference.
>       So..........WHAT am I missing ????
>
>Cheers
>
>Frank Condelli
>Almonte, Ontario, Canada
><A HREF="http://members.aol.com/BusFusion/bfhome.htm">BusFusion</A> a VW Camper camping event, Almonte, ON, June 10 ~ 13, 2004
>'87 Westy & Lionel Trains
>Member: <A HREF="http://www.vanagon.com/">Vanagon List</A>, <A HREF="http://www.bcn.net/~limbo/">LiMBO</A>, <A HREF="http://www.westfalia.qc.ca/">IWCCC</A> & <A HREF="http://www.ccvwc.ca/">CCVWC</A>
>Vanagon/Vanagon Westfalia Service in the Ottawa Valley
><A HREF="http://members.aol.com/Fkc43/stebro.htm">STEBRO/Vanagon Stainless Steel Mufflers</A>
><A HREF="http://members.aol.com/Fkc43/busindex.html">Frank Condelli & Associates</A> or http://frankcondelli.com
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