16 replies to this topic

[robson]

Afternoon all, my mini failed its mot on headlights (died on the way there!) and secondly on emmissions. Im running a 1380 stage 3, so its not the easiest to do, no cat either (94 carb engine) so they are quite strict on emmissions. After searching, i have seen that you can remove the breather pipe to the carb, or take off the manifold to servo feed (bypassing the over run valve)

I do not run the breather pipes into the carb, they are just in the engine bay therefore i run the carb breather blocked, by unblocking this and making the car idle quite badly, will this lower the emmissions? Also, when people do run the breathers into the carb, when they remove the pipe for the mot, is the goal or that just to stop the gas not entering the carb or is it to let the carb breathe cleaner air, by opening up the pipe.

Also, How would removing the servo/manifold pipe actually aid in the emmissions as my understanding was that it just enabled the servo to work correctly. Thanks

[The Matt]

Well, the techniques you have mentioned for getting a car through the MOT are bodges really. I guess the idea is that the manifold would suck in air, effectively making the engine run a little leaner.

If it's a '94 carb with no cat it needs to pass a default emmissions test, which means the CO has to be less than 3.5% and the HC has to be less than 1200 ppm. You should be able to squeeze it down to that with some carb fettling to be honest. Are you using a single 1.75" SU? Unless the car is running quite badly.

[Dan]

I believe that doing either is just a way of massively leaning out the engine on command. That has the effect of reducing the emissions but is not good for the engine's health. Most of what is drawn through the engine ventilation system is water so wouldn't affect the emissions anyhow. If the system is working properly there should be little oil vapour present. In your case all you should have to do is remove the plug on the emissions inlet at the carb. At your own risk of course and don't make any power runs with it unplugged, unless you like buying pistons.

[Big_Adam]

Could do what I did. MOT man twiddled it down. Went home. Twiddled it back up.

But thats was beacuse I had no idea how to properly set a carb up, which is why it was MASSIVELY over the limit.

[robson]

i tried it for about 30 seconds just now, idles but very badly. I thought that was the case too mini mad me however apparently not... mine are way within the limits you set, however im being tested as per having a cat (94) and i dont run one. I told the guy a cat would do nothing to a carb engined car but he didnt respond. So if i just do the little carb breather trick, he runs it on a fast idle for about a minute, will any harm be done?

[robson]

running a 1.75 HIF, very well setup currently.

Just phoned up, they said all 94 cars have to have a cat and so have to be tested as per cat fitted, meaning:

CO< 0.2%, HC < 200 ppm, Lambda 0.97 - 1.03

Surely no carb engined mini can achieve this, even with a cat (pointless)

Will the breather trick affect all aspects? the CO will be, not sure about lambda and HC

[The Matt]

Well, they're actually talking through their backsides!

This has been covered loads of times to be honest. Their emissions test database should tell them that the vehicle should be tested to default settings.

Take it to a garage that knows how to test cars properly!

[robson]

this guy even does minis for a mini resto company!

How can i prove he is wrong so that he has to do it to default?

[The Matt]

Well, he should be checking the engine number with the numbers stored in the database. Then the database should tell him what limits the vehicle should be tested to.

The other thing..........

Is it the original engine? Is the engine older than the original one?

[robson]

its not the original no, however the way he was saying it, even with my original engine in, the car would still need to be tested according to the machines 1994 setting - cat fitted. the engine is the same year

[The Matt]

Ooook, after a little SEARCH:

this

this

and this

Should help your cause!

[The Matt]

by the way, I used to be an MOT tester and I have looked into this before!

[robson]

from that link, mine is

First used between 1/8/92 and 31/7/94 - advanced emission test (CAT) if its running on petrol when presented, to the vehicle specific limits usually around CO<=0.3%, HC<=200ppm and Lambda 0.97 - 1.03. Remember from 1st August 2001 a basic emission test will be carried out initially.

so it should have a cat, and once did, however it does not anymore. They will just refuse to try on the other test setting as by the book its 94 and needs a cat... what now?

[robson]

Just took it back to be re tested, passed

after trying to convince the man for 15 mins that im correct, he obliged to do it the way i said

Thanks for the help, saved me trying to find a tester that knows what they are doing!

[Road Runner]

Who was doing the testing Downton???