# Exhaust manifold to pass SMOG - High NOX



## jrm2007 (Oct 12, 2007)

after about $4-$500 in to trying to pass my smog on this altima i bought for a deal i thought, it was discovered my exhaust manifod is cracked and allowing oxygen to get in and throw of my NOX. Failed SMOG. 

Any tips on removing exhaust manifold. I got as far as taking of heat plate but thoght twice about taking off the entire exhasut manifold. with my luck, was worried I was going to strip a dang bolt and make the situation worse.

any tips and removing??? does anyone experience on using Nissan or aftermarket exhaust manfiold, such as the one made by dorman. 

please advise. any info will be helpful.

thanks.


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## stock98altima (Sep 30, 2007)

NOx will not be produced from a cracked exhaust manifold, the only thing that will produce is highr O2 levels in a SMOG/emmisions test.

Nox is only produced when combustion chamber temperatures exceed 2500 degrees

look at your combustion chambers, high carbon can increase temps, as well as alot of other factors.


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## jrm2007 (Oct 12, 2007)

how do i check my combustion chambers? any experience on replacing the exhaust manifold?


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## jo31b (Oct 24, 2007)

I think the high NOx level would be from your crack, a leak in the exhaust would cause the system to change your air fuel mixture and maybe how much exhaust your EGR is recirculating to control the combustion temperature.


I haven't replaced a manifold so I can't help you on that one.


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