High NOX levels for smog check.

So went in for my smog check and my NOX level was double the standard. We ran the obd and no code came up. I checked the plugs and they are pretty new. Checked vacuum lines they seemed ok. Ran a sea foam system clean in fuel and intake. The levels came down but still too high. Changed the spark wires and coils. It came down a little more. Determined it was the catalytic conv. Got a whole new cat, pipe and flow master. Ran it on a dyno now it's back to where I started at double the standard at 1100. Any suggestions?

 

Might wanna check your egr valve. If there is one not sure. But a bad or not hooked up correctly egr will cause high. Nox.

 

Cool thank you lefty. Do you have a procedure for testing?

 

Hummm. No.lol my experience is with jeeps to be honest. If their similar you can test it with a vacuum gauge to see if the diaphragm moves. Otherwise I got nothing sorry. You could look in FSM and see if there's a procedure. It's linked in the stickys.