We'd recommend ensuring your Chevy Corvette is not running hot (cooling system running efficiently) and the fuel system is not lean; along with ensuring the EGR system is functioning properly. These are the three main things which could cause high NO. NO is created when engine combustion temps rise above 2500f. Any of the three conditions mentioned above can cause the engine to run hotter than normal; and the temp gauge will not necessarily indicate this.
Any vacuum leak can introduce "unmetered" air to the fuel mixture, leaning the fuel mixture and causing high NO; as well as very low CO. Along with vacuum leaks, any emission sensor problem which would indicate to the computer less than necessary fuel should be delivered to the combustion chambers will have the same effect; such as defective oxygen sensor, mass air flow sensor or the like.
We'd recommend a "fuel feedback test" to ensure your Chevy Corvette's emission sensors are working properly, the computer is receiving the sensor(s) signals, and commanding the fuel injectors to richen or lean out the fuel delivery.
Next is the EGR system. The EGR system introduces exhaust gases (inert gas) to the fuel mixture, lowering combustion volatility and reducing combustion temperatures.
Addressing the above mentioned concerns will more than likely lead you to finding the fault responsible for your Chevy Corvette high NO smog check failure.
