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Exhaust Emissions Test Fail


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#1 Tom Maguire

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Posted 19 May 2017 - 05:42 PM

I need some help. I have tried so hard these last few weeks to get my Mini ready for the L2B run. One of my biggest issue was getting it through an MOT. It was booked in to my local MOT center last Friday but i had problems with my wiper motor and finally got that fixed last night. I know that i was running out of time so it went for an MOT today but it failed on the emissions. I know that i wont be able to go on the run this Sunday but can you have a look at the attached gas analysis report for the MOT center and guide me in the right direction on how to get it through the MOT.1f622.png

 

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#2 1984mini25

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Posted 19 May 2017 - 05:50 PM

Why they couldn't do this during the mot is beyond me, Most nice testes do. On the bottom of the carb (assuming its a standard 84/85 998) is a brass nut, with it hooked up to the co machine wind it in/up a few flats until its reading around 2.5% co. That will bring the co within limits, not restrict performance too much (you can run it leaner, but you have to mashed the throttle more witch uses more fuel) and also bring down the hc.



#3 ukcooper

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Posted 19 May 2017 - 06:04 PM

Why should they, most moter's are not treated nice in fact id say most put up with a lot **** of people they only see once a year, mine are treaded to breakfast once a year by me pass or fail i dont care they get summit. just as a thank you for been there. they do little jobs with asking but that's not why I do it.

 

get the mini booked in on a rolling road and say it for a mot 



#4 cal844

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Posted 19 May 2017 - 06:33 PM

My tester does an emissions test a few days before, they're easy to adjust anyway!

#5 rww

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Posted 19 May 2017 - 06:53 PM

    Considering that the remedy to the emissions fail is so simple, this does appear that the Mot tester was being less than helpful. However, being fair minded he/she may not have any knowledge of A series carburation and it was a Friday !  You were certainly unlucky especially considering the multitude of things the antiquated Mini can fail on.

 

  The engine is burning (slightly) too much fuel as the exhaust analysis shows. As 1984Mini25 says there is a nut at the bottom of the carb. which can ( just ) be turned between the fingers which when screwed into the carb, anti - clockwise when viewed from above, will weaken ( reduce the petrol) the mixture. This may result in the car becoming a pig to drive but so be it, it will get you through the test and you can adjust it back afterwards.

 

In the 50 odd years I have been on the receiving end of Mot's I have ALWAYS accompanied the car through the test. Most testers are more than reasonable and as long as you do not interrupt them and only respond when spoken to I have found them always helpful. I have had them volunteer to adjust the mixture to achieve a pass providing there are no other issues. Better luck next time.  


Edited by rww, 19 May 2017 - 06:55 PM.


#6 Sprocket

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Posted 19 May 2017 - 07:11 PM

Looking at those results I don't think it's a clear case of adjusting the carb. 7% CO and 3000ppm HC could indicate something else such as poor ignition or even a missfire.

I'd want a four gas analysis done which comes under 'diagnostics' not an MOT.......

#7 KernowCooper

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Posted 19 May 2017 - 07:33 PM

If it fails the initial C/O test then the testers manual say re-do the teat at 2000rpm was this done, has it been serviced prior to the MOT ? if so and everything is correct then its a 30sec job to adjust and pass.



#8 Tom Maguire

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Posted 19 May 2017 - 07:35 PM

Thanks for all your advice. My MOT tester told me that he had to adjust my valves but i got the impression that he had not worked on my classic Minis before. One thing to mention, the last time i fulled up with petrol i put half a bottle of redex into the petrol tank and there was still half a tank of petrol in the car when i took it for the MOT.



#9 Tom Maguire

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Posted 19 May 2017 - 07:39 PM

If it fails the initial C/O test then the testers manual say re-do the teat at 2000rpm was this done, has it been serviced prior to the MOT ? if so and everything is correct then its a 30sec job to adjust and pass.

Hello Sparkie, i serviced it myself and it seamed to run fine. The engine is in good condition with no smoke and for a 998 it seam to have plenty of power. 



#10 KernowCooper

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Posted 19 May 2017 - 07:40 PM

So are the valve clearances right ? thats the trouble taking classics to garages who don;t understand them



#11 Tom Maguire

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Posted 19 May 2017 - 07:50 PM

So are the valve clearances right ? thats the trouble taking classics to garages who don;t understand them

Sparkie, I never had any trouble with valve clearance before, My Mini always seam to run fine. I haven't checked his work. I will take the cover of it tomorrow and have a look. What i will say its running a lot more lean now. There seams to be a big flat spot when i pull away so much that i have to pull out the choke to compensate



#12 cal844

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Posted 19 May 2017 - 08:23 PM

So are the valve clearances right ? thats the trouble taking classics to garages who don;t understand them

Sparkie, I never had any trouble with valve clearance before, My Mini always seam to run fine. I haven't checked his work. I will take the cover of it tomorrow and have a look. What i will say its running a lot more lean now. There seams to be a big flat spot when i pull away so much that i have to pull out the choke to compensate

If its passed just turn it back up?

#13 Tom Maguire

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Posted 19 May 2017 - 09:05 PM

Cal884
No it hasnt passed. I need to get the emissions adjusted and take it back for a retest.




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