I have 1994 chevrolet s-10 Blazer.
Emission was failed for HC too high.
I replace EGR valve, and ECM with PROM.
Cause EGR didn't get signal from ECM, but still don't get.
and I replaced catalytic converter 2yrs ago.
NO limit 938 my car reading 2963
HC limit 141 my car reading 15
CO limit 1.14 my car reading 0
Welcome to the forum. I don't know what you're asking. The EGR system is inoperative on yours. This results in higher combustion temperatures and excess oxygen both of which contribute to the formation of NOx gases. Fix the EGR system and your NOx emission should come down.