Emissions related question

I had my biennial smog check today. It passed inspection (only just) and so had a question for anyone who could shed any light on this. The NOx emissions were very high and in general the HC and CO emissions were also high on the 15mph test. The 25mph test got much lower readings. The results were as follows -

15mph - %CO2 15.1, %O2 0.1, HC(ppm) 46 (max allowed 74), CO(%) 0.31 (max 0.61), NO(ppm) 515 (max allowed 525)

25mph - %CO2 15.1, %O2 0.0, HC 11 (max allowed 58), CO 0.07 (max allowed 0.61), NO 357 (max allowed 812).

I'm not sure how to interpret these results especially as no fault codes have been set. Assuming that the high NOx levels are due to a lean mixture (high combustion temp) or a faulty O2 sensor why am I not getting any fault codes. Also some of the other readings suggest a rich mixture (such as the high CO readings). Also cannot understand why the drop off on the 25mph test as the rpm is only about 15 higher.

I cannot find the report from the smog test 2 years ago but as I recall the NOx emissions were also high on that test so I don't think it is something that has happened recently.

I've seen people on this forum brag about passing their emmisions tests with flying colours, and others who have failed. What can be the difference? Stricter California emmisions is one possible answer, but, I think it has to do with a poisoned catalytic converter. Since the cat is supposed to convert CO, CO² and NOx, I would guess this is your problem, as most others failing emmisions tests. The Metro has a 3-way Cat, and 95 and later models are equiped with two cats, an upstream converter bolted to the exhaust manifold, and the downstream converter, underneath the engine, near the oil pan.

Read this link for more info on poisoning of cats. http://en.wikipedia.org/wiki/Catalytic_Converter

Jai

Thanks for the input. I don't follow this forum enough to have read other people's posts regarding emissions but I agree it is relative. I believe most states do not have any form of emission controls anyway and the others that do have varying max levels so the whole thing is subjective without looking at the exact numbers. I believe the emission standards here in Southern California are more strict tham the rest of the state. While it is great that we are trying to reduce pollution I wonder in general how effective it is if many others are not doing so as the global weather and winds move air around from place to another all the time and California air does not simply stay in California.

What struck me was that the Ave number for all cars tested which is quoted on the test report is really low and makes my car's reading look bad. Ave numbers are for 15mph - HC 9, CO 0.02, NO 57 and at 25 mph HC 7, CO 0.03, NO 50 - all way below my readings.

Anyway to test the Cat?

hot_sd

"...While it is great that we are trying to reduce pollution I wonder in general how effective it is if many others are not doing so as the global weather and winds move air around from place to another all the time and California air does not simply stay in California..."

The first part of your thought above is key. Responsible behavior requires controlling the emissions at the source. Dying forests (acid rain) in the Northeast due to coal-fired power plants in the Midwest were an issue a number of years ago. Federal regulation was required to begin to address that one. Asking nicely (voluntary compliance) gets you nowhere when somebody's bottom line is involved. When the public interest is at stake, legal precedent has established that private profit-making ventures, or private behaviors (the vehicles we choose to drive) can be subject to certain restrictions.

My '96 1.0 l 5-spd (143k at the time) passed emissions here in CO, despite a P0420 code, relating to CAT efficiency, being thrown (the CEL was not lit during the inspection), so either sensors can be a little 'sensitive,' give bad readings, or my CAT's actually failing, despite the emissions being 'OK.' But as I understand the OBD-II system, it's intent is to be an 'earliest-possible' warning system for the operator, sending codes significantly in advance of total system failure.

Although the E-test values were well below what the state requires for this region (the rest of the state has no E-test, AFAIK), the values were marginally higher than the previous test, two years earlier (when in the hands of the PO).

-Mike

then you have to figure in all of the collectable cars and no offense to anyone but the "redneck" cars (affluent in Florida!) :)

sorry i couldnt help the last post :)

My mom has a 95 Grand Prix and when it was time for the emission test, the NOx numbers were so high that it failed, the car runs great, no check engine light, so I was stumped. After tearing into the intake, I found that the passage that is in the intake manifold for the EGR valve was totally blocked with sludge. After I cleaned it out, made sure the EGR valve was working correctly, it passed without any problems. I also had a co-worker with a 93 Grand Prix with the same engine that did the same thing and passed without problems after it was cleaned. Pull your EGR valve and make sure everything is still flowing as it should.

As for the emission tests, I am a firm believer in the Echeck program here in Ohio, however there are only a few counties that have to be tested, the county I used to live in and still work in is one of them. The county I live in now does not require it, and let me tell you, there are sooooo many cars that would fail the test in my county, it makes me sick, literaly, drive behind one of them for a few miles..... And then to top it all off, we had so many people complain about 19.50 for the test every other year, they took the money from the tobacco settlement to pay for the test, so they didnt get any more complaints about the cost!!!!!! And to make matters worse, if you fail, all you have to do is make up a reciept that you spend $250 ( I think that is the amount now) on trying to fix it, and then they give you a waiver, what is the point of even testing if you still allow the cars that pollute to still drive??????:banghead:

Emissions tests should be every car, every year, no exemptions!!!!!

Thanks for the reply. Unfortunately, my model (1.3L engine) has no EGR valve and so that is something that cannot be checked. My guess is that the cat is slowly dying - I guess I will find out if I still own this car in a couple of years and it goes for the smog check.

The emissions test here in southern cal is pretty strict although as I said in a previous post unless everyone is sufficiently concerned about the environment to have such strict rules not just in this country but globally then all this would only have a limited effect. I personally would like to see the development of and the move to cleaner fuels hopefully in the not too distant future.