whatbrown

I have spent over $600 this week on smog related items. These were just to get the ses light to turn off. Today, I went to smog my car and it failed the sniffer. Everything was fine except the nitrous oxide levels at 15mph. The levels at 25mph passed fairly easily. Does this make sense? My car was at only 1300 rpm in the failed test and 2000 in the one that passed. They have to do it in second gear apparently. Why would my levels be way lower at 2000 rpm than 1300 rpm? What can I do to lower my levels at lower rpm? I hate California.

whatbrown

Somebody please help me. Would running the test with the car cold help. I heard that nitrous oxide is caused by high combustion temperatures.

wait4me

iTrader: (10)

EGR valve not working probably. And you need to make the Vehicle run as hot as possible durring the test. 600!!! you should have just bought tuning software and shut off the codes...

GOaT Cheese

You probably failed in the Nitrates of oxygen (NOX) area, and not the Nitrous Oxide area. Nox is a byproduct of combustion, or more accurately, excessive combustion temperature. That being said, enter the EGR valve, the EGR valves primary function in life is to reduce NOX by introducing inert gasses to occupy combustion space in the cylinder, thereby cooling the flame front and reducing NOX. You also have a three way catalytic converter that also greatly ruduces NOX. What may have happened is that the Catalytic converter may not have been fully ignited at the lower speed and wasn't converting NOX like it is supposed to. At the higher engine speed, the converter "lights off" and works as designed. If you have a weak catalytic converter or a shaky EGR systrm, you could fail the NOX portion of the test. You can try and run the **** out of it on a local freeway, get it really hot (so the cat will work) and immediately smog it without any cool down time (they call this pre-conditioning). This usually works, alot of people try and smog cold cars and fail. Also make sure your EGR system is working perfectly. One more thing, look at your printout, if the "02" reading (oxygen content) is real high, like 2-3% then your Catalytic converter is bad and needs to be replaced, the 02 level on a good cat should read around .01 to .02%.

whatbrown

02 level is .48-.58%. I tested the car twice today. The second time the car was hotter as I had floored it up and down the bouelevard a couple of times. The numbers for nox and pretty much everything else that run were worse. If nox is directly related to temperature, why can't I just run it cold? The other numbers are all well within spec.

whatbrown

My main concern is that the nox levels were way higher at 15mph than 25mph. Is this because the egr can't be entirely effective yet? Is it the cat? How can more rpm's produce less nox?

GOaT Cheese

The higher RPM reduces NOX because the the converter is hotter. It is kind of a catch 22, The higher temp lets the cat reduce nox IF the cat is in good shape, if the cat is questionable, then the higher temp does hurt you. Your oxygen content is a bit high, that means the converter is weak, not bad, just weak. If it just won't pass after running it hard you may have to replace the converter. Or if you think there may be an issue with your EGR system you could look into that. What I would be worried about testing it cold is higher HC and CO numbers, which are much tighter than NOX. I don't know off the top of my what your car is allowed. You can try going to the local drug store and buying some Isopropyl rubbing alcohol, and adding 12-16 ounces to half a tank of fuel. The alcohol will cool the combustion temperature quite a bit and maybe you will pass, don't add too much though or the car will run like crap and you will fail in other areas.

whatbrown

I think I will test the car somewhat cold. Has anybody tried this? My co and hc numbers passed pretty easily, and only my nox is concerning me. I think it's worth a shot.

Doc

iTrader: (9)

All this for the Peoples Republic of Kalifornia? Does anybody think Aahnold's Hummer have any problem passing emissions? Think of all the money that you have spent on this crap and think about what you could have done with it for mods that would have it running stronger?

whatbrown

I do think about that Doc. I have other issues with the car that I can't deal with now because I have spent so much money on the smog crap. Does anybody think smogging the car when it's cool is a good idea? Like I said, it's only nox that was bad and the other areas passed easily.

2xLS1

iTrader: (25)

It might help if you described the car a little. Like what kind of car? Stock? Mods?

whatbrown

The car is a 96 ws6. It has shorty headers, catback, and k and n. Other than that, it is stock performance wise. I think I failed the nox portion of the test because my car runs really hot. I tested it when it had been driven hard just prior to testing. I think if I warm the car up completely, then park it for a few hours, and test it after that it would pass.

whatbrown

Failed smog again today. Car was tested while engine was cool. Nox numbers were similar to when engine was hot. It's weird because the nox easily passes at 25 mph, but fails pretty badly at 15mph. Do you guys think it's an egr issue?

brad8266

iTrader: (23)

Kalifornia sucks *****!!!

Id tune it and set stoich at like 16:1 just for the damn sniffer and then reflash back to 14.7:1 afterward. That way youll be nice and lean for the test, which will reduce emissions.

How many miles are on the car anyway? The cats may be going bad.

NHRAMAN

iTrader: (1)

ENGINE MUST BE HOT...

GOaT Cheese

I think your catalytic converter is just too weak. What was the O2 numbers for the last test?