Understanding emmision readings!

[ro284]

Can anyone explain what the readings from MOT emmisions test are and relate too please, as in what gases, parts per how much, etc.
cheers Bob

[Ricco_04]

The year of car depends on what tolerences you have.

Very basicially you have :

HC - Hydrocarbons
CO - Carbon Dioxide
NOX - Nitrogen oxide (not tested on my rex think this is year dependant?)

You will also have your Lambda tested which is how well your fuel is burning with the air provided.  Usually on later cars (say 1999 onwards) the optimum reading is 1.0 with a tolerence of 0.3 plus or minus.  For the FD the tolerence starts something around 1.65 IIRC.

Sure someone will have more detailed info for you.

[ro284]

Thanks Ricco, the reason i asked is my FD sailed through it\'s MOT even though i use premix, when i enquired i think the guy said the reading was 0.3 and the \'good range is up to 0.20, so i was well in! so well happy with that, but i might have got a zero in the wrong place there trying to explain it! it\'s a 92 K reg, no Apexi as yet!
Bob

[kbareham]

Bob
There is some info on the testing procedures here:
http://www.motuk.co.uk/manual_730.htm

The limits applied to UK cars are here:
http://www.bobmckay.co.uk/p_emissions.html

This is the reason that I wanted to get a pre 7/92 car, to avoid confusion about test requirements. It has been stated for imports that the dates differ, allowing later cars to be tested against the pre 92 limits. I don\'t have anything to back that up though.

Rgds
Keith