MOT and Emission

[is200 Newbie]

Another MOT passed and the first one with the "home made" exhaust I put on the car.

I am just interested to see what emission readings other owners have that still have the OEM exhaust on their car - I don't really understand the sheet that comes with the MOT read out but is as follows:

Fast Idle Test

CO % vol: Max limit = 0.2 / Actual = 0.14

HC PPM Vol: Max limit = 200 / Actual value = 59

Natural Idle Test

CO % Vol: Max limit = 0.3 / Actual Value = 0.16

Is this along the lines of an OEM exhaust?

 

 

 

[J Henderson]

Would love to tell you but I didn't even receive a printout of the emissions test when my car was MOT'd a couple of weeks ago. I thought that was strange.

[Britprius]

As long as you did not remove the cats, and there are no leaks in the exhaust system any modifications made will have no effect on emissions.

John

[madasahatter]

14 hours ago, is200 Newbie said:

Another MOT passed and the first one with the "home made" exhaust I put on the car.

I am just interested to see what emission readings other owners have that still have the OEM exhaust on their car - I don't really understand the sheet that comes with the MOT read out but is as follows:

Fast Idle Test

CO % vol: Max limit = 0.2 / Actual = 0.14

HC PPM Vol: Max limit = 200 / Actual value = 59

Natural Idle Test

CO % Vol: Max limit = 0.3 / Actual Value = 0.16

Is this along the lines of an OEM exhaust?

 

 

 

CO % Vol: Max Limit = 0.2 / Actual = 0.01

HC PPM Vol : Max Limit = 200 / Actual Value = 12

C0 % VOL :  Max Limit = 0.3 / Actual Volume = 0.01

This was mine on 23.3 2017 Standard Exhausts.

[Vintagesixtysix]

My last MOT

 

2006 manual 90,000 miles

OEM exhaust

 

Fast Idle Test

CO % vol: Max limit = 0.2 / Actual = 0.03

HC PPM Vol: Max limit = 200 / Actual value = 51

Natural Idle Test

CO % Vol: Max limit = 0.3 / Actual Value = 0.30 (not sure that this isn't an overprinted value of max limit)

 

 

 

 

Sent from my Iphone using Lexus OC

[johnatg]

I agree with John - exhaust changes downstream of the cats will have no effect on emissions.

But for the record, the emissions reported are relatively high.

My most recent MoT for the Lexus reads 0.01% CO and 12ppm HC on fast idle and 0.01% CO on Natural idle.

Incidentally, my wife's Mii reads 0.00% CO and 2ppm HC on fast idle and 0.00% CO on Natural idle.

Even my 25 year old MX-5 is cleaner  - 0.02% CO and 55ppm HC on fast idle - Natural idle figures not reported.

I wouldn't read too much into any of that though - a lot depends on the exact state of the engine tune on the day, how long the engine has been running for and so on - probably most importantly the state of the cats and the forward Oxygen sensors. And look at the trend over a number of MoT reports - if the emissions are rising over time, it may indicates deterioration of the cats and or Oxygen sensors..