I just bought a 94 Z28, for the most part everything is in good working order but it fails emissions terribly.
HC = 2.22 standard = 0.80
CO = 15.00 standard = 16.5
NOx = 2.50 standard = 3.08

I'm pretty sure its due to a performance chip the previous owner had installed.
Problem is I need to know where that chip would be located. is it the chip that really easy to replace located in the small panel on top or is it somewhere else?

 

There is no "chip" in a 94 or newer F-Body. The chip is sealed in the PCM, and can only be flash programmed. You would have to make a copy of the existing file, and let someone with TunerCat take a look at it to determine if it is stock or otherwise.

Have you checked to make sure there is a healthy catalytic convertor in the correct location?

 

Wait a second..... like I said before. The car runs great and other then the performance CHIP seems to be running normal.
If there is a problem with the cat. Something else must be causing it. I think it's whatever they did to the ECM.... any suggestions?

 

If it has a 'chip', it will be plugged into the harness between the harness and the PCM. To check, pull the PCM out and see if there is a little black box plugged into it. As before mentioned, A good cat is needed to pass. My car has a Jet chip plugged into it and I passed Cal emissions testing. Does you car idle smooth or have a miss that would make it run rich? What are your O2's showing at idle?

 

Well, I pulled out the PCM athe other day and didn't see anything like that. My guess would be that the guy that told me this misunderstood what was being done to his car. As for the idle, it's good. About where it should be. There is a noticable difference in sound. Sounds a little tuffer then it should. More like an engine with exhaust work and a mild cam. No loss of power either. As a matter of fact, I raced my 11.4 second Z28 and it kept up much better than expected. I'm thinking I'm going to flash a stock profile to the PCM, and throw a spare cat on there for the emissions test.