Well I inspected my car before I started working on it and after I Worked on it.
Its a 90 Accord EX with 241K Miles about 500miles on rebuild.

Before:
HC PPM: 15 MPH Limit 125 reading 144

CO%: 15 MPH Limit .50 Reading 6.80
25 MPH Limit .73 Reading 1.12

NO ppm: 25 MPH Limit 1591 Reading 1767


Then After I did rebuild and cleaning up the thing:

CO%: 15 MPH Limit .50 Reading .92
25 MPH Limit .73 Reading .98

NO ppm: 15 MPH Limit 1636 Reading 2277
25 MPH Limit 1591 Reading 2111

Well I have a couple ideas but i want to know what you guys think.

Apparently I have a small exhaust leak, but I have no idea where it is buying some of that exhaust sealer stuff and see what i can do.
Also I have a overheating problem, which i thought was good, but i have no idea if it overheated during the test.
Also, i have replaced filter, o2 sensor, cleaned EGR.
I have three ideas of what parts it could be TPS, MAP or Catalytic converter.

 

If you haven't cleaned the EGR ports, I would start there. They are almost certainly plugged and will cause high NOX. Check DIY forum for EGR cleanout procedures.

Check PCV valve and hoses carefully for leaks, splits, or blockage.

Check the exhaust by adding some engine cleanout to the running engine and look for smoke at exhaust leaks. Leaks ahead of the O2 sensor might cause excess fuel to be added attempting to balance the fuel/air mixture.

Suggest having a cold cooling system leak test to locate any external leaks. Hopefully, new head gasket is good.

good luck

 

You pulled all of the EGR plugs (5 or 6, can't remember) and cleaned the ports under them?

EDIT: way to slow at typing, I see TX posted....also to correct myself I think the 90 had welded plugs that are a bit different.

 

I did not do the plugs as i will do those tomorrow. All hoses are good.

Now I did find a exhaust leak after the 02 sensor right before the catalytic converter that someone welded on. I put some brake fluid through intake and cause it to smoke and a lot came out from that area, everywhere else was good.

Can carbon build up cause high Carbon Monoxide? Thanks for the help.