PistonHeads.com Forum

Evo IX emissions?



Original Poster:

4,671 posts

163 months

Tuesday 25th September 2012
quotequote all
So, in Colorado, after a vehicle is 5 years old, you have to get it emissions tested every year. This can be avoided by driveing through a certain number of roadside testing stations at certain intervals, a feat that this year sadly I failed to achieve.

As a result, I had to go to a emissions testing station. Which was comic in itself, as they only take cash, of which I had none on me, and the low fuel light was on.

After a quick stroll to the gas station to use their ATM, and another stroll back, with visions of hugely expensive failures looming, along with it running out of fuel pulling out of the test center, I passed.

Now, what was interesting were the actual figures.

For a start, the US doesn't use CO2 for taxation, so the Evo is set to run rich as standard, hence an almost comic CO2 gpm compared to UK spec cars.

What I'm wondering is, if anyone has any UK numbers to compare? I'm interested in seeing if the goal of chasing a low CO2 figure is at the expense of everything else, or if other numbers are comparable.

The form also has the required pass figures, and again I'm wondering if anyone can compare to UK testing - are these in the same order of magnitude, or just utterly laughably high, or low?

Readings Limits
HC gpm 0.0817 1.2000
CO gpm 0.7941 15.0000
CO2 gpm 413.4955!
NOx gpm 0.0551 1.5000


Not sure if this is the right place for this, but I figure it's probably the best location to get a response from another Evo owner. It might be worth mocing it elsewhere, mods, if you know of a better place.


6,523 posts

127 months

Tuesday 25th September 2012
quotequote all
We have to have our cars emissions tested each year but its not to do with the tax rather than a agreed limit for all cars of certain ages

I havent got any old emissions sheets with mine since my emissions test is often carried out after I have left the mot station wink


2,976 posts

129 months

Tuesday 25th September 2012
quotequote all
From the MOT Manual
If a vehicle, which is subject to the catalyst emission test, has a dual exhaust system, the test should be performed on both tail pipes and the results averaged. This is done by adding together the results and dividing by two, eg
Fast idle test
1st pipe:
0.4% CO, 25ppm HC, ~ = 1.01
2nd pipe:
0.2% CO, 15ppm HC, ~ = 1.03
Average CO: 0.4+0.2 / 2 =0.3%
Average HC: 25+15 / 2 =20ppm
Average ~: 1.01+1.03 /2 =1.02
Idle Test
1st pipe: 0.45% CO
2nd pipe: 0.35% CO
Average CO: 0.45+0.3 /2 =0.4%
The Results of this type of test must be entered manually onto the VTS Device.

no idea how to compare with above


Original Poster:

4,671 posts

163 months

Tuesday 25th September 2012
quotequote all
Thanks for that - unfortunately, I've no idea, either.

Oh well, thought it might be interesting to compare and contrast; should have known it wouldn't be that simple!

Nearest CO2 figure I could get for a UK spec car was 347g CO2, so my 413 seemed quite high.


9,998 posts

117 months

Thursday 27th September 2012
quotequote all
CO2g/km is published for most modern cars sold in Europe and is around 320 g/km for the CT9A Evos, but I believe this is over a standard course/test, not a stationary one with the car on idle. The engine would typically run leaner when idling/low load, so you would expect lower CO2g/km under these conditions, but your figures aren't a million miles away from what's published.

As for the particulates and other gasses, my Evo always ran squeaky clean when it had the cat in, the readings were pretty much 0.

One of my test results were as follows:

Fast Idle

CO % vol. Max limit: 0.200, Evo: 0.029

HC ppm Max limit: 200, Evo: 12

Natural Idle

CO % vol. Max limit: 0.300, Evo: 0.017!!!!

Edited by youngsyr on Thursday 27th September 12:33



Original Poster:

4,671 posts

163 months

Thursday 27th September 2012
quotequote all
Ta for that.

The emissions test was actually on a dyno, and as I noticed yesterday, my figures are per mile, not kilometer, so it actually looks like the numbers are pretty comparable.