i smoged my car last week and failed, nox max at 15mph is 711 measured was 1208...changed cat and failed again at 1003?! at 25mph passed with 680's on both trial(max is 754 at 25mph) and everything else passed too...dont know what the hell it could be? someone help me out quick? i'm going to try changing the o2 sensor and cleaning out the intake mani and use some additives, i need to bring the nox level by 300 what else can i do??

 

did you change your oil, cap and rotor, spark plugs, spark plug wires?

 

i dont think any of those will change the nox level

 

[QUOTE=HmgLauj69] i'm going to try changing the o2 sensor [QUOTE]

oh, i thought you changed your o2 sensor. that's your problem right there.

 

NOx is mostly produced by high combustion chamber temperatures. Many cars use a EGR system to reduce the combustion temp, some others get by using valve overlap.

What mods are you running?

Without knowing your mods, I would look at reducing ignition advance and if you have them setting the camgears as 0,0.

 

EGR valve sound right u probly got carbon biuld up in it poor actone in it should clean it out
should pass

 

i have a person that do dirty smog and he tells me every thing that is wrong most the time is egr valve and u said eveything els pass right?????

 

integras don't have egr valves. Like stumpy said, you have to reduce your combustion temp.? Do you consume a lot of oil? If you do, I would suggest using a heavy weight oil just for the test. Maybe using higher octane will also bring down the temps.

One thing is for shure though, make sure you check your timing and checking your cam timing wouldn't be bad too. If your timing is at spec, reduce it by 2 or 3 degrees.

 

PASS!! just smoged it again today for the third time and passed!, when i first smoged nox was 1200, second time at 1056, third was 530... all of which was at 15mph (max limit 711)....first time: everything was stock, second time: new cat, third try: changed oil, 02 sensor, ran my tank near empty then pumped 91 octane instead of what i always use 87, but most importantly SEA FOAM! this stuff is awesome! i dont think the others did much, the sea foam brought my nox level way down, over 500! some good stuff