Need help to lower NOx numbers for smog...

[DrifTkInG180sX]

what's up everyone... I failed smog but it was just the NOx numbers that were a little high...i recently fixed my egr problem and I was thinking it might be my cat...I attached a picture of my smog paper report so if you guys can take a look at it and let me know what i can do...thanks everyone..

[AKADriver]

I would wager the cat is functioning normally.

What EGR problem were you having? Malfunctioning EGR is the most obvious cause of high NOx emissions. A lean air-fuel ratio is the other, but your CO numbers are high enough that I doubt you're running lean.

[Var]

Try running some Seafoam through your engine to get rid of all the carbon. Carbon buildup increases compression ratio which increases temperatures which increases NOx. Also set your timing back by 3 degrees. If you have a DOHC, you can set it as far back as 17ºBTDC and for a SOHC you can set it back to 12ºBTDC and still pass the timing check. Also if you can convince the smog guy to run your car in first gear, then second gear your chances of passing will increase. Also you can sit in the car and rev it @ 2500rpm for 3 minutes before he smogs it. If the guy is cool he'll let you do it cause he's not allowed to do it himself. A hot cat is an effective cat.

[idlafie]

what's up everyone... I failed smog but it was just the NOx numbers that were a little high...i recently fixed my egr problem and I was thinking it might be my cat...I attached a picture of my smog paper report so if you guys can take a look at it and let me know what i can do...thanks everyone..

Drift,
Have you checked your catalytic converter to see if the honeycomb inside the cat is still in good shape? When I failed smog 3 years ago, I blew NO readings of 1031 at 15 mph & 891 at 25 mph. It turns out that I had a melted cat & I didn't even know about it....the car ran fine & all. Anyhow after swapping out my cat, I passed smog with flying colors. Never did figure out why the hell my cat melted.
Anyhow, I've attached a picture so you can see what happened to my cat.
ID
'95 SE

[thx247]

I've noticed on 3 DOHC motors they all burn through a little rubber vac line that comes off of that round disc thing just above the EGR valve on the intake side of the car.

[Pacman]

I've noticed on 3 DOHC motors they all burn through a little rubber vac line that comes off of that round disc thing just above the EGR valve on the intake side of the car.


My '91 engine did that, too. So, you can make that 4 engines.

[ghostuss]

Try running some Seafoam through your engine to get rid of all the carbon. Carbon buildup increases compression ratio which increases temperatures which increases NOx. Also set your timing back by 3 degrees. If you have a DOHC, you can set it as far back as 17ºBTDC and for a SOHC you can set it back to 12ºBTDC and still pass the timing check. Also if you can convince the smog guy to run your car in first gear, then second gear your chances of passing will increase. Also you can sit in the car and rev it @ 2500rpm for 3 minutes before he smogs it. If the guy is cool he'll let you do it cause he's not allowed to do it himself. A hot cat is an effective cat.

Trust this guy. Last time I checked, he was working at a smog station HAHA, damn Var. :goyou: