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High Nox levels. Help

 
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Old 08-25-2009, 08:23 PM
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High Nox levels. Help

I went to go smog my 99 Lude base and it failed because of high Nox levels. The car has a air/fuel ratio and its always in the red(lean zone) or led dissapears when cruising at 70. At 80 it shows stoich yellow range. I was wondering what i can do to fix it. The car has DC 4-2-1 ceramic headers. I noticed that it doent have a donut gasket or any gaskets to the converter. what can i do?
thanks
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Old 08-25-2009, 08:51 PM
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Re: High Nox levels. Help

High Nox means high combustion temps in the cylinder. A lean A/F will definitely send the nox flyin.Other contributors are high compression ratios, over advanced timing and even vaccum leaks... Do you have any internal mods that would raise compression??? If so yer pretty much S.O.L. If not... try to obtain the 14.7 stoich and check yer timing. Also a tune up (oil change, air filter etc etc) makes a big difference as well... Also make sure yer CAT is nice and toasty before throwing it on a smog dyno... oh yeah get that gasket on their....good luck

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Old 08-25-2009, 08:59 PM
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Re: High Nox levels. Help

when i bought the car the only eng. mods are aem intake and the DC headers. Do the headers need the Donut Gasket? I also noticed a little crack happening on the headers where 4 and 1 meet
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Old 08-25-2009, 09:01 PM
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Re: High Nox levels. Help

Yes you need that gasket... and that crack is most likely the culprit. The lack of gasket and the crack are the same if not worse than a vaccum leak... I would find a new header OEM or aftermarket doesn't really matter as long as I'ts CARB approved. change the oil and clean up the air filter and you should be good
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Old 08-25-2009, 09:04 PM
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Re: High Nox levels. Help

Where can i get the Donut gasket and can you acually weld the headers. they are the powder coated headers?
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Old 08-25-2009, 09:13 PM
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Re: High Nox levels. Help

I think the diameter is the same as stock for the gasket but I'm not positive. You should be able to pick one up at any parts store for pretty cheap. As far as welding goes... You can weld ceramic coated headers. I'ts a lot of work but can be done. You'd have to grind the coating off and mig weld it. sand it down and put some high temp paint on it. Taking it out of course...
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Old 08-26-2009, 11:15 AM
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Re: High Nox levels. Help

cool thanx for the help
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Old 08-26-2009, 11:20 AM
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Re: High Nox levels. Help

if going aftermarket on Header ...again
dont buy ceramic!!
purchase stainless steel
look in resource guide for help!!
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Old 08-26-2009, 11:56 AM
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Re: High Nox levels. Help

you can get the whole exhaust gasket set on ebay too. Might as well if you have to take the header off anyway.
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