That VW specialist does not know how to troubleshoot emission failures.
Excessive NOx is usually caused by over-advanced ignition timing and/or
a defective catalytic converter. Bad valves usually show up as excessive
HC. So will an ignition miss or a lean condition miss fire. A rich
mixture will show up as excessive CO. Many cars use an EGR valve to
recirculate the exhaust gasses into the engine during part load
conditions. This dilutes the mixture with an inert gass, effectively
lowering the peak flame temperature which lowers the production of NOx.
The waterboxer does not have this device. The 3-way cat when working
reduces all 3 pollutants as long as the mixture is near perfect. That is
why we have the O2 sensor.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Melvin Mudgett-Price
Sent: Wednesday, August 25, 2004 11:11 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Failed Emissions Check

Took my van for its Ohio e-Check yesterday. The engine has 20,000 on a
rebuilt Boston Bob. It passed with flying colors 2 years ago. This time
it failed on Nitrous Oxide emissions, they are supposed to be around
900, mine were 1,900.

I called my regular mechanic (VW specialist) and he said there was
nothing he could do, when van's start failing their emissions test
that's usually the end for them. This sounds like total bs to me and I
don't know why he doesn't seem to want to even look at the van. Called
another VW shop and they said no problem, bring it in.

Now to my question. What sort of things would cause the "NO" to be high.
I would like have some idea not because the mechanic will try bamboozle
me but because I don't like to be in the position where he could.

Thanks
Melvin
83.5 Westy