Hello Fellows
I bought a 1992 f250 5.8 v8 197k miles that did not pass smog in California. Before I had it tested, I replaced the oil, air, and oil filters, and pcv. The truck runs and idles really well and so I was surprised that it didn't pass. It tested high for: HC 487, CO 9.99 and a check engine light with 173 The tech at the shop mentioned It might be the oxygen sensor or at worst case the Cat Converter. It turns out the fuel pressure regulator was causing it to run extremely rich. I ended up replacing the plugs, coil, cap and rotor, oxygen sensor, fuel filter, fuel cleaning additive, fuel pressure generator, and oil again since I think that fuel was getting into the oil. I also removed and cleaned the idle control valve. I really feel a difference in power and idle stability now. I have driven it a few times to see if the check engine light come back after codes were cleared.... no light I'm happy to say.
I am ready to have it re tested now before my 30 day re test runs out, but wonder if there is anything else I can do before I take it to re test. Any suggestions would be greatly appreciated. Thank you much and hope you had a great Thanksgiving.

 

Just don't get it tagged as a gross polluter. I don't know how many times you can fail before they tag you. best to run the codes & see if any come up. Hopefully you cleared th first ones.