You can check that the computer is _responding_ to the O2 sensor by watching
them dance... Check the voltage at the O2 sensor wire at the test connector
(positive VOM lead to O2 sensor wire, negative to ground). Measure in the
0-4V range (approx.). With the engine full warm and running at 2000rpm you
should get crosscounts from .2-.8V (+/- .15V) one to two times per second.
If no, could be problem with ECU, but check harness first. Next best guess
is airflow meter.  In the shop I'd try replacing ECU and airflow meter
w/known good parts, AFTER checking wiring harness using the Bentley pinout
guide (I STILL haven't memorized all the terminals on the main plug, can you
imagine?)- not wanting to fry a perfectly good part with a bad harness. Not
that it seems like yours is bad, given the thing's running well, mostly.  By
the way, HOW high are CO readings? Where is HC in all this? What's the
German smog check? Are you in Germany?

Coby Smolens, Owner
Valley Wagonworks
VW Bus and Vanagon Repair
1535 Sir Francis Drake Blvd.
San Anselmo, CA 94960
415 457-5628
www.wagonworks.com

> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM]On Behalf
> Of Pabst Michael
> Sent: Tuesday, June 01, 1999 5:38 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: 86 digifant running rich
>
>
> Here's my puzzler: 86 digifant. Runs good but: High CO emissions
> at idle as well as at fast idle (3krpm), fails the German smog
> check, 15 mpg (on long as well as on short distance rides),
> checked compression, temp sensors and replaced OXS sensor.
> Digifant unit defective ?
> Michael
> 86 7-seater
> 80 Westy
> 86 Quantum
>