Ok so I have been browsing all the smog related posts but I want to make sure I got this right before I either do it myself or take it to a shop. So first and foremost I will list my results:
HC at 15mph 288 and should be 83
HC at 25mph 247 and should be 48

CO at 15mph .85 and should be .48
CO at 25mph .85 and should be .46

Now so far everyone I have talked to in person said to change the cat but I have read that you should only do that if you NO is over. Also the EGR valve mostly has to do with the NO so I dont need to check that either, right?

My plugs, wires and fuel filter were done june of 07
My oil and airfilter were done 3 days before I failed my test
and I also filled the tank with 91

Now I did just notice that my AIR pump hose is not connected to my K&N but I would think if that would have been a problem the smog guy would have noticed it.

So its going to be fuel system, misfiring or vacuum?


Oh and the only aftermarkets I have are the flowmasters, msd, and K&N FIPK which is smog friendly.

 

Are you OBDI or OBDII? Based on you allowable HC it sounds like you are OBDI.

You are way high on HC so something is definitely not right with the basics
of air, fuel and spark. How many miles on your car? What is your gas mileage?
Does it seem down on power? Any SES codes?

 

What were your NOx results?

High HC AND high CO generally means its running rich. But the NOx results may be significant if they are close to the limit.

 

I have the OBD1. The car has been a little down on power but I thought it was the gas I was using but I am getting around 15 mpg. I have 130,000 miles on it. The engine light isnt on but I havent hooked it up to a computer yet. Should I?

Did I forget to mention its a 95 z28?

 

Yes, not all codes trigger the SES light.

 

Unless you have your foot in it constanly you should get better then 15 mpg
all around and at least 20-22 for highway. Sounds like its running rich to me.
If your optispark is original I'm sure it's a contibutor as well. If you did not replace
the O2 sensors when you did the plugs you may want to check and see if they
are working properly. I would not make a decision on the catalytic until you
resolve the high HC condition. Have you done a leak down test for the injectors?
Do you know if you have an adjustable fuel pressure regulator and if it's set
properly?