breaking in new cat for emissions?

[tac0meat]

does a catalytic converter need to be "broken in" before it will work? i just failed my emmission only on the NOX part, i was at like 2000 ppm which was way too high, they said it was either my egr or cat. i dont have an egr so it must have been my cat. got the bad cat replaced and after about 50 miles i got it retested and it still failed, it brought the numbers much closer to passing but not enough. the guy at the inspection place said that i need to put a few hundred miles on the cat before it really starts to work like it should

 

[Alec]

Sounds reasonable, but I don't know if it's true. The cat works with heat and chemistry. The compounds in the cat have to fully heat up to interact with the exhaust to clean it in a nutshell. This is one reason the truck should be nice and warm when you get it inspected. You also want the truck warm so the engine runs in closed loop mode which is cleaner.

But anyway, since a cat works on heat and with the compounds inside it, it would seem reasonable that it would need a few heating and cooling cycles to work properly.

 

[Texan01]

Run it for a week, then take it fully warmed up to the inspection place. Also put new plugs in to get it to burn cleaner if it's been a few years since they were replaced. (Unless you've got fairly new plugs and it's not missing)

Last time I replaced a cat was on my old '76 Chevelle and I think I waited a week or so before I took it back to get sniffed and it passed then.

 

[kontinu1]

how much did it cost to have to cat replaced? Mine also failed a while back. (private inspection passed it). Dec. i have to get it inspected again I may have to get a new cat also. I don't have an egr valve.

 

[tac0meat]

cost me 185 total, that was just to replace one cat, the place said it was the rear cat that was bad, the front one was ok. i dunno if this is the going price, but it was alot cheaper than 300 for just the cat on my friends honda.

 

[williecume]

are they inspecting it right then or is there a long wait (like an hour+)? the cat could be cooking just enough that the engine goes into cold start mode and dumps more fuel.

but it would be safe to run it for a week. also did you change the o2 sensors?

 

[tac0meat]

im usually not waitin any longer than 5 minutes before they put it up. ive put about 500 miles on it, and gone through several heat/cool cycles on it. im gonna have em check it again on monday. the guys at the shop know me so they have been doing "trial runs" instead of using up my one free reinspection, so if i have to go back a couple of times it doesn treally cost me. i have not changed my o2 sensors lately and if im still too high when i get it checked on monday, ill look into those. my dilution was right at 14.6-14.7 which is right where it ought to be so i dont think too much fuel is being burned. all other numbers were very good and well below the limits. except for the NOX, but we'll see how it goes monday