Chevrolet Repair: emissions failed, chevrolet corvette, law dictates

Question
ok.  I just bought a 1984 chevrolet corvette.  The cat converter had been replaced and the guy I bought it from hadnt had it in his name more than a year so naturally I assumed (I know, I know) that he got it smogged to transfer it into his name.  Not an uneducated guess entirely.  I mean he did have to smog it to transfer it but assumeing it was done legitimately was based on the new parts.  The fact that he speaks very broken english didnt help the process, but here I am.  Going back to him as California law dictates would be more hassle than it would be worth I'm afraid due to the language barrier.  Well now for my question........

I guess I should just post the results from the emissions test that I had done some two days ago and see what you might be able to deduct from them:

15 MPH results:
    CO2% 7.70
    O2%  9.69
    HC(PPM) MAX.     128    
            MEASURED 105    PASS
    CO (%)  MAX      0.80
            MEASURED 0.83   FAIL
    NO(PPM) MAX      1106
            MEASURED   70   PASS

25 MPH results:
    CO2(%)  8.15
    O2 (%)  9.11
    HC(PPM) MAX       103
            MEASURED   76     PASS
    CO (%)  MAX      0.60
            MEASURED 0.76     FAIL
    NO(PPM) MAX       936
            MEASURED   79     PASS

Over all it failed as you can see.  What would cause the CO levels to be high?  Barely I might add.  Also what would cause the NO levels to be so low?  Well under the limit.  Should that be a concern?  I just need to know what component would cause these levels to be off.  Is it possible that what ever is causeing the CO level to be high could also be causeing the NO level to be low?

 Thanks
 Allen Pinney

Answer
Here in Michigan, we haven't smog tested for quite some years.  If your HC was high, I would say raw gas and suspect a rich mixture.  The CAT is supposed to take the gasses and make CO2.  Since CO is getting out, one would assume the CAT is bad, but maybe it is just overwhelmed.  The job of EGR is to take exhaust gas and reburn it for a cleaner exhaust gas.  If that is failing, it could overwhelm the CAT.  Check the EGR system.  Is it vacuum operated?  Is the hose good?  Disconnect it and see if things change at all.  Use a vacuum pump and operate the EGR valve.  Is it moving?

Good luck.