Emissions

[Diamondback]

Ok, so now that I finally have this '90 2.9L Ranger running well, I have to get it to pass emissions. It passes with flying colors except for NOx. The NOx is double what it should be. In previous repairs to get the truck to run, I've replaced the fuel pump, fuel filter, fuel pressure regulator and the MAP sensor. Before I started working on it, the catalytic converter had been replaced. It's been on for 2 years and about 300 miles.

The mechanic that tested the emissions suggested that the catalytic converter was a cheap Autzone speacial and not an OEM replacement. He's saying that it is a 2-part converter and not a 3-part. He verified the timing and says that the only culprit has to be the catalyitic converter. Does this make sense?

 

[MAKG]

If there is no reducing bed in the cat, that would give you high NOx. But I didn't think you could even find those anymore, cheap or not.

So would advanced timing, or anything that would lean the mixture (such as vacuum leaks or a false-rich oxygen sensor reading).