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
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