87 Buick 2.5L engine fails smog test in Ca.

Had my 87 Buick 2.5L 102K miles on it smog tested yesterday and it failed NOX readings both @ 15mph and 25mph. The numbers were twice that is allowed 1400-1500ppm
and allowed is 750-800ppm. The HC and CO are both in the low range of allowed. I did a tune up of plugs and filers and oil change first and warm the car up before the test. I thought it might be the EGR valve and when we tested it with vacuum it didn't move or even pull a vacuum. So I bought a new one and tested it and it was the same. Any ideas what the problem might be? Could the catalytic converter really clean up that high of NOX? reply to dave snipped-for-privacy@hotmail.nospam.com (remove the nospam)
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Check the EGR valve diaphragm with the engine running - it should move when the engine is revved after it's warmed up. Also if you manually push it open at idle, the engine should run rough or die - if not the passages are probably clogged and need cleaning.
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Robert Hancock Saskatoon, SK, Canada
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