Failed Emissions

[treel98]

My Bronco ii failed emissions on Friday. it failed due to oxides of nitrogen. Had more than the standards. Want to fix without taking it to a shop to have it diagnosed. I have no idea what it could be it passed 2 years ago and had not been driven since had fairly new gas in it so i don't know if that would make a difference.

Any advice would be appreciated.

Tyler

 

[adsm08]

NOx is produced by high combustion temps. The combustion temps must exceed 1500*F to create NOx. EGR systems are in place to reduce combustion temps and thus reduce the amount of NOx produced. The catalytic converter is there to catch the rest of the NOx, along with any excess hydrocarbons (unburnt fuel) and carbon monoxide, a normal but poisonous byproduct of combustion, and through a chemical reaction turn those three compounds into harmless carbon dioxide (not an environmental pollutant no matter how loud Al Gore, the EPA, and the green-****tards scream) and water.

Since you have a 90 you have no EGR. Assuming all the other numbers were in range it sounds like it is time for a new cat. Not the furry find that catches mice.

The only other things to check out are if the engine is running hot, or if it is running lean. Both can cause excess NOx. If the HC numbers are extremely low if may be lean.

 

[treel98]

Ill post the results and the numbers from the emissions paper tomorrow. But I'm going to have to guess that it is the catalytic converter.

 

[adsm08]

I'd say that's a safe bet.

 

[ab_slack]

Question for Adsm08, is it possible that there is some carbon buildup in the cylinder resulting in higher combustion temps?

The soft of thing Seafoam intake injection treatment is supposed to resolve? Even if technically accurate in theory, perhaps such a condition in an engine is more theory than reality?

Just taking a wild guess here, I would think that if there was lots of carbon buildup that it would need to be running rich in which case HC would probably be high in addition to NOx.

 

[WarHawk-AVG]

Try this as well

 

[treel98]

well passing emissions is the least of my worries as of noon today... transmission blew. now have to talk it over with parents on wether we are keeping it and puting more money into it or get rid of it

 

[kimcrwbr1]

When it rains EH. I was going to say if it hasent been run for a while take it on a road trip for a few hours and blow the cobwebs out. Kinna hard to do now if it dont go forward!

 

[naford]

Not to thread jack but just for curiosity. Could an air filter that is dirty cause these same symptoms?

 

[alwaysFlOoReD]

AFAIK on a carbed engine a plugged filter would cause a rich mixture which would actually cool the engine. On a efi engine I would guess that the o2 would correct the rich mixture but I don't see it running hot, just lose power.