Still Will Not Pass Smog (nox)

[sjtilney]

1995 3.4L

So I took my car to have it smogged and it didn't pass because the nox was really high. I replaced the ERG valve, both o2 sensors and put in a 180 degree thermostat, I took it to have it retested and the nox was still high, it actually was a little higher. anything else I can do besides sell the car?

[youngsc]

Re: Still Will Not Pass Smog (nox)

Cat converter?

[BLLDOGG]

Re: Still Will Not Pass Smog (nox)

seafoam

[sjtilney]

Re: Still Will Not Pass Smog (nox)

If was the cat converter I beleive everthing would be off, not just the nox. What is the deal with seafoam. Has anyone ever actually made their car pass smog because of it?

[97rs4life]

Re: Still Will Not Pass Smog (nox)

it is said to help pass smog, but I don't know of anyone that did it and passed where they didn't pass before it. Maybe someone here will chime in, MI doesn't have those crap laws. :)

[Camaro Dom]

Re: Still Will Not Pass Smog (nox)

lol but michigan has plety of crap on its own... nothing like rising taxes in an economy so bad we dont sell out the arena where our hockey team is in the playoffs...

EDIT: on topic... the egr valve itself might not be bad, but maybe theres a carbon buildup in it. i dunno if seafoam would neccessarily get to it (the brake booster line feeds from the back of the intake and the EGR is at the front... i think that the best way to handle it would be to take off that upper intake and make sure there isnt any blockages.
NOx emissions are created by excessively high combustion chamber temps. the EGR is the biggest contributor to that. I'd also take a scan tool and see if you cant manually operate the egr valves. there may be hotspots in the combustion chamber, so i'd try the seafoam next, and maybe new spark plugs... past that dude, i dont know...