MOT Emissions Test

[111Robin]

I have one Mini that still needs to pass the emissions test, running twin HS4, but don't have a working gas analyser. Apart from colour tune type devices, is anyone using a gas analyser at home or are you just winding the jets up as far as possible while still being driveable ?. Last time it was mot'd I had access to an analyser so it wasn't an issue. I don't want to buy an analyser just for this, everything else is visual only on the exhaust so don't really need one.

[Peter Laidler]

Hi Rob, for the first couple of MoT's, my still pretty-much new, with mileage under a few thousand X reg Rover RCS-5 continually failed the gas test part of the MoT without a degree of 'fettling'. Then one of the younger testers found that there was a small-print type exemption for the minis. This solved the prob and it's been fine ever since. I'm sure someone here will be able to quote the exemption chapter and verse. Got to be worth a try

[111Robin]

Peter i don't think there's any exemption for mine, it's pre-cat, presumably your x reg is Mpi so maybe its different for that. I wound the jets up by hand the day before as,far as i could but was way above the limit on CO and HC so will need to get in with the SU wrench and wind them up further and take it back for retest but would like to know if it's ok before i go back. Maybe the needles I'm running are too rich, it's years since i built them and can't remember what they are. I think the last time it was tested it was running a single HIF so was easier to set up.

['S'-type]

If yours is pre-cat you should only have to meet the less demanding standard in the test as follows:

All vehicles Pre 1st August 1975 - Visual Only

All vehicles Post 31st July 1975, Pre 1st August 1986 - less than 4.5%CO and less than 1200ppm HC

All Vehicles Post 31st July 1986, Pre 1st August 1992 - less than 3.5%CO and less than 1200ppm HC[/b]

(this is where it gets complicated)
All vehicles Post July 31st 1992 Pre 1st August 1995 - 'BET test'. Natural idle - less than 0.3%CO. Fast idle - less than 0.2%CO, Less than 200ppm HC, between 0.97 and 1.03 Lambda.

If the emissions result from the 'BET test' is a fail, the Tester must then look for vehicle specific data and carry out a 'CAT test' or 'Non CAT' test depending on the available data in the annex. (Chances are any Mini will fail the 'BET (1992-1995) test' especially without a catalytic converter)

All Vehicles Post 31st July 1992, pre 1st August 1995 - 'CAT test' - Can the Tester find an exact match in the analyser database or the In-Service Emissions book?

What this means is if the vehicle is NOT listed in the database you only have to pass the non-cat test.

For cars from 1995 that are not mentioned in the annex of the database the limit is reduced to 0.5% CO 0. 3 for those listed.

To sun up if your car is pre 1992 you're looking at less than 3.5%CO
if it's 92-95 with no closed-loop Cat it's the same less than 3.5%CO
Post 95 cars it depends if they can be found in the tester database.

So get those jets turned up and you should be OK!

I had to research this as my son's car is a 93 last of the carbs with an open loop cat. They failed it on the more stringent test until I pointed out the above to them.

Government Doc has it all here
https://assets.publishing.service.gov.u ... dition.pdf
Mini model code XN is on page 128
not sure if link will work.

I should point out that it's based on how the car left the factory. People can't get round it by just removing the Cat and claiming it never had one!

[111Robin]

Thanks, just checked the same document, mine is 1989 so :
From 1/8/86 and before 1/8/92
3.5% vol CO, 0.12% vol HC(1200ppm)
No specific
requirement
but engine
must not be
clearly
above its
normal
idling speed

I'll just wind the jets up as far as possible while still being able to drive it, or just stop outside the test station and wind them up before the test.

[Peter Laidler]

Jeeeeees S-Type. I bet you were a chemistry teacher! Makes me wish I'd studied Chemistry instead of Fizziks. Got that Rob but didn't realise the age differences between my would-be X reg and your 89 reg. But it looks like you could easily slip into the let-out zone.

[111Robin]

No loopholes Peter, has to meet the limits prescribed. Emissions was the only thing I couldn't check before the test, knew it might be an issue, so had my SU jet spanner in my pocket. They did allow me to adjust them after it failed but I couldn't get onto the hexes without scalding my hand so had to give up. I have a week to take it back so will screw them right up and keep my fingers crossed.