What was the failure? Did they have dyno to test the NOx emissions to know
they were still high? Yes sometimes a cat can be fouled up and driving may
clean it. A sign of a cat failing is that it takes too much time to "light
up" and do its job. 

High NOx is usually caused by over advanced ignition timing, an excessively
lean mixture or excessive load. The Cat is the only device on the Vanagon to
clean it up. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
David M
Sent: Wednesday, July 10, 2013 2:40 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Emissions - does this sound right

 
�Took my Vanagon in for diagnosis/repair after it failed emissions��. I'm
not sure I can beleieve anything this shop says but they said it was running
rich and they adjusted the timing. They said this fixed the CO levels but
the NOX levels are still borderline.
They said because it had been running rich, I need to take the van away and
drive it hard for around 50 miles to clean out the cat. Does this sound
right? Sounded weird to me.
�
David (1987 Wolfsburg)