my 96 turbo Integra pass emission 2years ago and now it fail. I did the same thing I did 2 years ago... put back stock ecu, injectors,spark plugs, remove charge pipe,BTC is at 16*.
HC 2.04 limit is 1.2
CO 11.08 limit is 15.0
NOx 4.1 limit is 2.0

I'm thinking that my Catalytic Converter might be gone. The NOx seem to spike up under acceleration/load. The HC seem to be pretty HIGH at low speed and go DOWN to almost nothing at high speed.

Here are a few thing I'm planning to replace.
Cap and Rotor
Denso O2 sensor
Universal 3" Catalytic Converter
Oil Change
Radiator Fluid

Please Chime in if you can help...

 

Well, if replacing the cat is already on the "to do" list, I think you'll need to complete those changes and see how it tests again.

Otherwise, ISO Heet or "Guaranteed to Pass" might be something to add to the gas tank to try improving those numbers. Either one will help with both HC and NOx, as they both burn cooler (NOx reduction) and cleaner (less HC) than gas.

 

x2