London Low Emission Zone - Feasiblility Study

egr valve
nox is caused by heat, the egr valve gets rid of some of the heat by sending some of the exhaust gas back through the motor

the passing limit is 1500 my cars reading was 2700. I was wondering what could i do to lower it i changed the manifold, cat converter, graduated or did the cars timing, the first reading was 3200 the second reading was 3500 after changing the cat converter, i also took it to the mechanic and he put in some liquid which cleaned out the cars system. which lowered it to 2700 i really need some help all these mechanics have been ripping me off. I have spent almost 500 dollars fixing it i got a 95 accord with a vtech engine. The mechanic said the problem is the hoses are clogged I dont know if to believe him because i have paid so much already and there has not been a real big change. Can someone tell me what i should fix or if anyone knows of someone in connecticut who could help me out. I have seriously almost ran out of money. email me player2a2003@yahoo.com i mean i dont mind paying 300 as long as i pass the test. the only thing wrong is the Nox and i dont know what to fix. If someone knows of anyone who can hook me up just email me. Player2a2003@yahoo.com

The problem is with the exhaust gas recirculation valve. Its either stuck open, stuck closed or the lines going to or from it a plugged. That is the only thing that controls NOX. To replace the valve and clean the lines will probably cost around $300 or a little more.

Yes, the EGR is the most likely cause. Other causes are a bad catalytic converter, of a high operating temperature caused by a faulty thermostat, low coolant, or a cooling fan not working.

Unfortunately, I learned this during a vehicle inspection whereas it failed the emissions portion of the test.

HC and CO were low… no check engine light… cat is new (old had NO catalyst element inside)… new secondary ignition… new distributor assy (pick-up coil broke apart and the windings ended wrapped around the shaft)… new timing belt.

At 175,000 miles, it runs like a champ… I have one additional fact: this particular application came with no EGR valve (its sister car, the Geo Prizm, is configured the same way).

Short of me jacking with the ignition timing or the fuel’s octane level, has anyone had any experience with resolving this type of problem or working with this year model of Corolla?

me living in a state that has emissions tests done,i have worked on a lot of cars to get them to pass the test.i believe your timing is out of range just enough to have it fail.your best bet is to check the timing and correct it.or even find someone who will play with the timing just enough to get it to pass then put the timing back to where it was.also there is this stuff you can buy at your local parts store you put in the gas to help it pass.even putting in a few bottles of dry gas will help it pass.but that’s if you fail because the car is running too rich.

HIGH SPEED LOW SPEED
STD. READING STD READING
NOX(PPM) 878 1184 FAIL 970 1040 FAIL

make sure your exhaust is hot when going in the testing machine.

a hot cat converter works better than a cold one

My 92 Olds Cutlass Ciera 3.1 L V6 fails NOx emission. Other emission test criteria are OK. Got new catalytic converter and muffler on. They did not help. Any suggestion about part repairs or replacement to reduce NOx level? Thank you!
Thanks to Archer Christifori for taking time to respond to my question.
Here is some additional detail. A few years back, O2 sensor was replaced to pass other emission test criteria such as, CO, etc. It seems EGR is a deive to control NOx emission for many car models. I searched online, as well as going to AutoZone store to check out if my car model actually has an EGR. The store did not have it, Online websites have not led me to any "correct" part for this model year. So, I am presently under impression that Olds Cutlass Ciera 92, V6 3.1L does not have an EGR! Am I missing something here?

Also, I did try to replace MAF once. That did neither solve the problem !

Further suggestions are definitely welcome! Thanks.
Thanks to Hugg2dz for the ideas. Tried some of those a few years back. Want to find if there is any other effective way.

The EGR system is what reduces NOx emmissions… you may also want to check the O2 sensor as well.

NOx is a generic term for mono-nitrogen oxides,
and are produced with the combustion of fuel.
Nitrogen enriched gasoline is a recent product
of Shell that makes claims of all sorts of things.
In reality, this ‘nitrogen enriched gasoline’ is
nothing more than a gasoline additive. It is
just another of the additives that are allowed
by the EPA. Additives are required to be put
into gasoline to reduce emissions that are
produced by the fuel combustion. Between
those additives, and the catalytic converter
you get the most reduction of emissions.
(there are other things that contribute to
reductions, but the two mentioned here
do the most)

So, to answer your question, nitrogen
enriched gasoline reduces those harmful
emissions, BUT it isn’t really any better
than any other of the mandated additives
required by the EPA. All it, and all the
others additives, does is to help clean
those carbon emissions from inside the
engine. Additives are nothing more than
an engine detergent, no matter what the
claims made by the different companies.
(did you know that transmission fluid is
a very high detergent? Adding a half
pint of tranny fluid to your engine oil, and
about a pint to a tank of gas does much
to help clean the engine, and work as
a ‘top oil’ in the gas for an upper engine
valve lubricant. If nothing else, just the
pint to your gas with each tankful can
do well.)

tell me what this could be caused from? My check engine light came on too.

The reason you go to these places is so they can tell you how well it runs and what is wrong if you have a problem. Many times it can be as simple as a bad gas cap to a bad catalytic converter. I don’t know where you took it but they should have told you what was wrong from the test.

on the co’s it barly failed. and the car dose not have a egr valve what else could it be?

You most likely have two different issues to deal with.
CO is partially burned fuel, and is a sign of too much fuel for the air in the engine.
The causes can be —
1) Lazy or defective Oxygen sensor
2) MAP or MAF slightly out of range
3) Fuel pressure regulator out of range
4) Stuck open thermostat
5) Coolant temperature sensor out of range
6) Failing Catalytic Converter
The diagnostics involved require LOGICAL procedures in eliminating each of the causes, and there are tests to determine where the failure lies.
NOx is Oxides of Nitrogen, and is a result of very high cylinder temperatures combined with pressure (compression)
If there is NO EGR valve, then the manufacturer has chosen other methods of reducing the NOx, such as ignition timing modification, cam timing (some makes) temperature management, and PCM control of fuel, and of course the Catalytic converter.
Again, there are tests we can run to determine where the failure is.
Be very wary of anyone who looks at the failure report and says without testing anything, "ah, just throw a Cat on it" or "Just tune it up, it’ll pass".
It might do the trick, but at a possibly greater cost than actually testing the car to find the cause.
Your BEST option is to go to a Licensed REPUTABLE SMOG repair facility and pay them their diagnostic fee, and follow their recommendations. You CAN choose the shot in the dark method, ot the shotgun approach, but you will be less than satisfied, and probably some poorer for the experience.

Good Luck

In atmospheric chemistry ppm refers to ‘parts per million by volume’ so in essence 1 ppm = 10^-6 cu.metre

So V = 10^-6 cu.metres

Now use the ideal gas law (PV=nRT) to determine the number of moles (n) and multiply that by the average molecular weight of NoX to determine the mass.

This will give you the density/concentration of NoX

Notes:
M.W N2O = 44.0128 g/mol (you may want to use a MW more relevant to your problem)