California Smog check - what is "NO"

[hpctoy]

I've got to get my 4runner smog check done. It's got 215k miles. Last time I had it checked, it failed and I had to take it to a repair station (lots of money!). Last time, they replaced an oxygen sensor. When the repair was done, it still barely passed: "NO" was at 507 ppm and max is 508 ppm at 15 mph. The car originally failed because HC was at 37 (34 is max) and NO was at 834 (508 is max).

I don't want to fail and have a bunch of crap to mess with. I've run fuel system cleaner through, changed plugs, changed oil and will fill with premium before the test. Anything in particular I can do for the "NO" numbers?

The 4runner runs great, averages 19-20 mpg, but it ran great before the last smog also.

Thanks for any ideas.

 

[JohnsD90]

Floor it on the highway a few days prior and hold it to really burn whatsever in the CAT's (haha stupid cali dual CAT's) out, and then when you bring them the truck to sniff it make sure the engine is up to tempurature and not cold.

 

[Stick Figure]

heat in the cats is key ... my last check the guy had to do it twice to get it to pass because the cats cooled too long... we even pushed it pretty hard on the free way before hand and it was tested almost as soon as we got there. I know mine is in need of new cats to be perfect though.

 

[bikerjosh]

JUst went through this. Replaced plugs, wires, pcv valve, oil, filter, cleaned maf & throttle body, replaced suspect 02 sensor; in the end I needed a cat. Walker sells CARB approved cats, should be able to get a universal (weld in) that is approved for around $150 online.

As the others have said though heat is key. You can go flog the crap out of your 4runner on the highway and if it sits idling at the smog place while they process paper work and set up the test it can cool down below the threshold. Even after my new cat install, the smog tech put a rod against the gas pedal and ran the vehicle at 3500 rpm to warm up the cat before he started the test.

Good luck, let me know if you need any help.
Josh
PS- your car has two cats correct?