Originally Posted by 240sxTuck

Not as bad as mine, lol. Gross Polluter all across the board! I just got mine done hot, which is pricey, but easy to do. I plan on passing legit next time i need to smog it.

Cat should be the last thing you replace. I would start small. Go ahead and seafoam it (probably gonna wanna change your spark plugs afterwards). Check for vacuum leaks. Make sure all your solenoids are hooked up right, and working (EGR, SCV, AIV). Make sure it's timed and idling correctly (20 degrees BTDC, 700 +/- 50 RPM). Make sure there are no exhaust leaks. Check for EGR, BPT, AIV, and SCV function. If all that checks out, replace the cannister.

I'm no expert at all, but your results makes me think there's something wrong with your valves or timing (assuming everything else i mentioned is working). Check valve lash, and make sure they're all seating properly. I would also do a compression test on all 4 cylinders. It can tell you if you have a bent valve, or if they're opening early. It might also be a good idea to check your injectors, make sure they're not staying on too long. It's bizarre to me that your HC and CO are fine on the low speed test, but GP on the high speed test, and your NOx is the opposite. What was your CO2% for each test? High amounts of HC and CO means there's not enough heat to burn off all the fuel in the cylinder, and won't produce a lot of CO2. High NOx can mean there's too much heat in the cylinder.

It would also help to know how well the engine runs. is it smooth or rough? are their any RPM ranges where it starts performing poorly?