New MOT and Exhaust

D

Davz

Active member
 Wellington, Shropshire
This week I have been getting a few quotes from exhaust fitters to remove the secondary cats and replace with a custom made stainless X or H pipe.
One of the companies (powerflow) refused the work due to "there are new MOT regulations due in May which mean ANY emission control components missing, will fail an MOT, this even includes things like EGR valves etc."

I have attached an image from the guidance provided to mot centres and it does state a major defect if emission components are missing.

The Z4 doesn't need the secondary cats to pass an emissions test, or so I have read, but I have also read that the secondary cat is not a cat but a silencer........which is correct?

Really not sure now if I should be removing the centre section for an X or H pipe but wanted a little bit more sound and improve the free revving nature of the engine.
 

Attachments

  • missing.JPG
    missing.JPG
    79 KB · Views: 1,007
AFAIK any visible mods to cats now equal a fail.. of course a clean install would go through without issues as emissions are met and cats are still there.
 
Davz said:
would it not fail as original spec means 4 cats?
Click to expand...

Depends how MOT testers get the specs, it's going to be one of those grey areas.. like exhausts that are louder than standard should be a fail but there's no way of telling. If it's listed somewhere that it has 4 then I'd say you're better of getting sports cats installed rather than getting rid of 2 completely.
 
Mike, thanks for confirming they are silencers, I had read conflicting info on this. BUT does this mean a fail due to noise?
Are custom stainless exhausts going to fail if they are a slight bit louder than standard? Is there a Decibel rating for all cars? Has Treesa May opened a can of worms?
 
Davz said:
Mike, thanks for confirming they are silencers, I had read conflicting info on this. BUT does this mean a fail due to noise?
Are custom stainless exhausts going to fail if they are a slight bit louder than standard? Is there a Decibel rating for all cars? Has Treesa May opened a can of worms?
Click to expand...

I can't see any problems with removing them, however I would simply open them from above and insert straight pipes before welding up again so they look completely OEM. But, in my experience, removing/bypassing them doesn't really increase the "noise" levels. I've modded plenty of OEM backboxes that will however increase the noise, but not drone in use.

Also regarding nosie, I don't think for the MOT they have a predefined level, unlike the SVA test where they use a sound meter a certain distance from the exhaust at specific revs.

Mike
 
reading the mot advice section on noise, the word "subjectively" is a concern, does this mean that one mot tester will fail your car while another thinks it is ok and pass it?
 

Attachments

  • noise.JPG
    noise.JPG
    147.3 KB · Views: 971
Davz said:
This week I have been getting a few quotes from exhaust fitters to remove the secondary cats and replace with a custom made stainless X or H pipe.
One of the companies (powerflow) refused the work due to "there are new MOT regulations due in May which mean ANY emission control components missing, will fail an MOT, this even includes things like EGR valves etc."

I have attached an image from the guidance provided to mot centres and it does state a major defect if emission components are missing.

The Z4 doesn't need the secondary cats to pass an emissions test, or so I have read, but I have also read that the secondary cat is not a cat but a silencer........which is correct?

Really not sure now if I should be removing the centre section for an X or H pipe but wanted a little bit more sound and improve the free revving nature of the engine.
Click to expand...

How well do you know the guys at the garage where you get your MOT done?
 
markalp said:
How well do you know the guys at the garage where you get your MOT done?
Click to expand...
not in the slightest!
This change to the mot will affect anyone who has a louder exhaust than standard as it is a "subjective" test
 
Davz said:
markalp said:
How well do you know the guys at the garage where you get your MOT done?
Click to expand...
not in the slightest!
This change to the mot will affect anyone who has a louder exhaust than standard as it is a "subjective" test
Click to expand...

Have you tried popping down the MOT center and asking them, tell them what you want to do and ask if it will affect the new MOT.
 
Davz said:
One of the companies (powerflow) refused the work due to "there are new MOT regulations due in May which mean ANY emission control components missing, will fail an MOT, this even includes things like EGR valves etc."
Click to expand...

We had a problem getting the wife's mini through 'controle technique' in Luxembourg (their equivalent of the MOT). They failed it because it had a non-type approved exhaust system and they said they couldn't confirm whether or not it had any effect on back pressure and consequent effect on the emissions control equipment.

We brought the car back to the UK in the end because there was no way I was going to splash out on a new 'type approved' system.

I did wonder if this might come to the UK eventually as part of the attempt to standardise roadworthiness testing across the EU. I thin k that project has been kicked into the long grass.

Incidentally we bought the exhaust system from Miltek in 2013 and the car had been sailing through the Luxembourg MOT every year without any problems until last year. It is a full 'cat-back' stainless system which doesn't make the car any louder but is considerably less expensive than the original type approved one
 
You must log in or register to reply here.
Back
Top Bottom