Help: Can't Pass Smog

Hi Guys:

Need some help getting my car to pass smog. Two years ago, I barely passed smog. Was quite high on HC. So I installed a new after market catalytic converter (Bosal). Needless to say, the old catalytic converter was shot. It rattled like crazy when I pulled it out.

Passed all emissions except for NO. My reading at 15mph was 2700 and at 25mph it was 750. I changed my spark plugs and EGR valve but the readings didn't change at all. Any idea what could be the problem? Could this be the new catalytic converter? I looked on Bosal's web site but it doesn't state that it can't be used in California. However, it doesn't state that it is a three way cat converter as well. The guy at Autozone, where I purchased the cat, doesn't know either.

Based on those readings do you guys think it's the cat or do I have another problem somewhere else. I checked for vaccum leaks and didn't find any.

Any help is appreciated.

Thanks,
Claude

High HC is from poor ignition or a lean mixture

High CO is from a rich mixture

As for NOx... EGR problem... but you replaced it... there are a few vacuum lines to the valve that the egr runs off of... not sure where to start look for problems

For now...
Check that your engine is heating up to normal operating temp... check the coolant system... maybe a thermostat problem?
Adjust the timing...
Lean the A/F mixture to increase engine temp or richen it to lower it... this may increase HC or CO but the Cat should take care of the rest.

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Quote:

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Originally Posted by http://www.naftc.wvu.edu/technical/indepth/CNG/CNG2.html

NOx emission mainly depends on combustion temperature and combustion duration...Time is the second factor in the occurrence of NO. The contribution of NO formation is more significant , if the mixture is burned early . Because the early burned mixture has more time to reach equilibrium. Another appearance of time factor is at different engine speeds. At higher engine speeds contribution of NOx is lower due to the less time required to achieve the engine cycle.

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Retard ignition timing a little... thats what I got from online to help reduce NOx.

Other then that maybe the fuel octane... haven't searched on that yet.

Other then that I'd guess you're right and the cat isn't a three way.

Doubt it could be a thermostat. I replaced that about two years ago because it broke. The A/F mixture is interesting since I recently replaced the carburetor. I didn't have a propane tank to properly set the A/F mixture however. I didn't think that it could effect NO though. I'll try enriching the mixture. Would I have seen any side effects from running with a very lean mixture? Didn't smell anything abnormal from the exhaust and the car has been running well. I have noticed that fuel efficiency hasn't been great lately though.

Thanks,
Claude

don't retard the timing. in cali it has to be set to stock or you fail. you might be able to get away with one degree off.

dang you guys are strict strict.