MOT emissions test curiosity

Howard

Howard

Howard

Soldato
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Evening all,

Just asking this out of academic interest really! Had my MX-5 MOTd this morning (passed, of course ;) ) and was looking at the emissions test results.

Now it's a pre-cat test, but how is it different to the >1993 (or is it 1994?) test?

Limit is 3.5% Carbon Monoxde and 1200 Hydrocarbons PPM. Mine got 0.07% and 51PPM respectively. Is that good? Lol


Are 'modern' emissions tests that are done at idle measuring the same things, but with a lower tolerance?


Cheers :cool:
 
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Hmm, I got it on my last printout, or maybe I'm just remembering what was on the screen? I'm pretty sure it has to be close enough to 1 on my car.
 
What was your lambda reading? Out of interest.
Click to expand...

Pre cat tests don't measure Lambda.

Mot emmisions are:-

First used before 1st August 1975
Visual smoke test

First used before 1st August 1986
Metered test at idle (non-catalyst test)
max 4.5%CO by vol
max 0.12%HC by vol (1200ppm)

First used before 1st August 1992
Metered test at idle (non-catalyst test)
max 3.5%CO by vol
max 0.12%HC by vol (1200ppm)

For cars first used after 1st August 1992 you have to check the 6th, 8th and 9th characters of the VIN plate. These tests are applicable for post 1st August 1992 factory cars and for post 1st August 1998 amateur built cars. An example standard is show below for a Caterham R500:
Seven 1.8 R500 16v
Max idle CO 0.5% vol
Min idle speed 750
Max idle speed 1200
Max fast idle CO 0.3% vol
Max fast idle HC 200 ppm
Min fast idle lambda 0.95
Max fast idle lambda 1.09
Min fast idle speed 2500
Max fast idle speed 3000
Min oil temp for test 75 deg C

For cars first used after 1st August 1992 but before 1st August 1995 that don't fit in the above VIN Code groups there are a further set of rules depending on the date of first use:
Metered test at idle (non-catalyst test) max 3.5%CO by vol
max 0.12%HC by vol (1200ppm)

First used on or after 1st August 1995 with no VIN group:
Max idle CO 0.5% vol
Max fast idle CO 0.3% vol
Max fast idle HC 200 ppm
Min fast idle lambda 0.97
Max fast idle lambda 1.03
Min fast idle speed 2500
Max fast idle speed 3000
 
Last edited by a moderator:
amigafan2003 said:
For cars first used after 1st August 1992 but before 1st August 1995 that don't fit in the above VIN Code groups there are a further set of rules depending on the date of first use:
Metered test at idle (non-catalyst test) max 3.5%CO by vol
max 0.12%HC by vol (1200ppm)
Click to expand...

That's what earlier MX5 imports are under like mine which is handy. :)
 
Yes, the same rules also apply to kit cars that use Zetec engines out of 92-95 Mondeos - no vin code group on a self built kit car :-)
 
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