Failed NCT because of high CO emissions! :(

Mr.Diagnostic

Sparks400 wrote:

If it's emitted from the exhaust it's an emission. I had a car fail on this high lambda (as you pointed out) due to a small hole further back in the exhaust system.

But it is not emitted from the exhaust.


The first thing to remember about emissions based on info from an NCT cert is that the NCT machine only shows and prints half the info required to form an opinion.

Mr Magnolia

Mr.Diagnostic wrote:

But it is not emitted from the exhaust.

Ok, still not clear to me what the measure of lambda is:o I thought it was too much air being exausted, is this just a resultant?

craichoe

Jesus H, just go get the car serviced.

High CO emissions could be any number of reasons and "Mr NCT" is just guessing. They'll need to bring it in and check various components.

Could be:
1. A Shattered CAT
2. Dirty/Malfunctioning Air Flow meter

P.S. Not getting your Car serviced for 2 years is just asking for trouble, regardless of mileage, do you even know when your timing belt was last changed !

JHMEG

Mr.Diagnostic wrote:

But it is not emitted from the exhaust.

sparky400 wrote:

Ok, still not clear to me what the measure of lambda is I thought it was too much air being exausted, is this just a resultant?

Air coming through a hole in the exhaust does not qualify as "emissions"!!:rolleyes:
What comes from the engine exhaust (thru the cat) are emissions.

Mr.Diagnostic

Sparks400 wrote:

Ok, still not clear to me what the measure of lambda is:o I thought it was too much air being exausted, is this just a resultant?

It is not a measurement, it is a calculated value. The calculation happens in the gas analyser. All of the exhaust gasses can effect the lambda value. Exhaust gas analysis is quite a complicated subject. If you are interested enough you could google "Brettschneider equation".

This is unlikely to help the OP much though. Best advice would be to get it serviced, 2 years is way too long, and get the garage to check gasses after.

Mr.Diagnostic

JHMEG wrote:

Air coming through a hole in the exhaust does not qualify as "emissions"!!:rolleyes:
What comes from the engine exhaust (thru the cat) are emissions.

I suppose it depends on what your defination of "emissions" is. Anything that comes out the exhaust is emissions in my book.
I posted in answer to Sparks who said that Lambda was emitted from the exhaust.

MAYPOP

craichoe wrote:

Jesus H, just go get the car serviced.

end of.

JHMEG

Mr.Diagnostic wrote:

I suppose it depends on what your defination of "emissions" is. Anything that comes out the exhaust is emissions in my book.

Well, I suppose fair enough. I would consider anything that comes out of the engine and through the emissions control system (cat being last part) to be emissions. But I wouldn't classify air drawn in thru a hole in the exhaust pipe and coming out the tailpipe to be emissions.

Either way the OP needs to get a service and get the car diagnosed. Revving the stone is not gonna help in my opinion.

Mr Magnolia

Mr.Diagnostic wrote:

It is not a measurement, it is a calculated value. The calculation happens in the gas analyser. All of the exhaust gasses can effect the lambda value. Exhaust gas analysis is quite a complicated subject. If you are interested enough you could google "Brettschneider equation".

Perfect, question answered.

Thanks Mr.Diagnostic.

Mr Magnolia

JHMEG wrote:

Revving the stones out of a car cleans out the soot, and is a common practice to clean out diesels as a smoke test is part of the NCT for diesels.

JHMEG wrote:

Either way the OP needs to get a service and get the car diagnosed.

Agree totally, off to the Garage with ya OP....


Post #4

Sparks400 wrote:

Injector cleaner & rev' the shoite out of the engine on the way down to the next test, this gets rid of any build up of soot/smoke etc in the exhaust system. Also, make sure the engine has had a good drive before the test and is well warmed up.

If the car hasn't been serviced recently you may need to do it. Oil change, oil filter, air filter.

Let us know how you get on

py2006

Will yiz relax! I will make inquiries in the next day or so re Service. I will let yiz know how I get on.

Anybody wanna buy an MX5?

Wossack

py2006 wrote:

Will yiz relax! I will make inquiries in the next day or so re Service. I will let yiz know how I get on.

Anybody wanna buy an MX5?

FSH?

theAwakening

i have a performance exhaust on my car. it a dual tip one. will i fail on emissions do ye think?

apologies if thats a stupid question.