On Tue, 16 Jun 2009 13:03:10 -0700, David M <covrambles@YAHOO.COM> wrote:

>My 1987 Wolfsburg 2.1L automatic just failed the AZ emissions test for
the first time. >-David (Tempe, AZ)

David -

I had exactly the same problem with my 85 and adding a new cat did not
change the NOX much at all. Before you do anything, check all your exhaust
system flanges and gaskets. Any leak creates an air pulse which fools your
O2 sensor and makes the car run too lean and with high NOX. Next thing to
check is the entire intake system. Look for leaks, loose clamps, bad
gaslets, bad cold start aux air regulator valve, etc. Any air that enters
your engine that doesn't pass thru your AFM will also make the engine run
too lean and results in high NOX readings. Be sure you check for intake
and exhaust system leaks before you invest in a cat. When you determine it
is the cat, avoid cheap aftermarket ones - they don't seem to work that
well.

Walter
85 Vanagon 1.9