De-catting after IVA

[spyder dryver]

There's a thread running in GG re. the MOT test and de-catted cars. It seems that the removal of the cat may result in failure regardless of emission test results.
So, in the case of a de-catted Q-plated car that only has to pass visual smoke test what might the result be?
If the car required a cat at IVA is this info available to the MOT tester?
This won't affect me but I understand that de-catting is a popular post-IVA mod.

[ugg10]

At IVA the emissions test for the rest of the life of the car is based on the engine age at IVA. This is noted on the MOT database and the log book IIRC. So if you are using a new ish engine (i.e. post 1995) it will need injection and Cat to pass IVA, the emission limits for such an engine noted being on the log book/MOT system. Removing the Cat will mean you will fail MOT normally. I think IVA now has dissassociated the reg mark with the emissions i.e. you can get a Q plate assigned (assembled from a collection of parts, not enough points from the donor) but still have modern engine emissions requirements on the log book.

This is the system as I see it but I am sure others will correct if it is not.

[spyder dryver]

ugg10 said:

At IVA the emissions test for the rest of the life of the car is based on the engine age at IVA.

AFAIK a "Q" plate car only has to pass a "visual smoke check" at MOT regardless of engine age or emissions data on its V5. In the past this quirk has allowed you to de-cat with impunity.
But what of the future?

[Dave Brookes]

For MOT testing:
Emissions are based on the age of the car or the age of the engine whichever is older.

http://www.motuk.co.uk/manual_730.htm

[Fury1630]

Dave Brookes said:

For MOT testing:
Emissions are based on the age of the car or the age of the engine whichever is older.

http://www.motuk.co.uk/manual_730.htm

It's more complex than that, "home built" cars have theier own rules which say soething like visible smoke only unless a figure is noted on the V5.

Unless they've changed them again.

[spyder dryver]

From the same manual...
See note 3.b

http://www.motuk.co.uk/manual/how_to_use_page_one....

b. Vehicles having a Q plate registration when presented for MOT are to
be treated as being first used on 1 January 1971


Is this the latest manual that we are both quoting?

The "Q" plate "visual smoke check only" quirk still exists AFAIK.
I have just found a document that suggests that cat removal will only result in a fail on a vehicle that requires a FULL Cat Test. Page8 Sect.7
So not "Q" plates then.
http://www.dft.gov.uk/vosa/repository/MoT%20-%20Is...

[PeteS2k]

I keep reading that emissions standards for MOT testing are recorded on the V5 for kit cars. I must've been lucky that someone in the process at VOSA/DVLA neglected to do that for me! I have no such notes on my V5. My Q plate with a 2003 engine was IVAd in 2010 to the full Cat-equipped standard, but has been MOTd on visible smoke only.

There doesn't seem to be any consistency with this. I would suggest the only accurate answer is to ask your specific MOT tester what standards he will be testing your specific car to.

[FlossyThePig]

I remember hearing a conversation at Stoneleigh a few years ago. One of the people in the discussion had developed the engine mamnagement system for the K series engine which required the catalyst to be in place for optimium running.

[Dave Brookes]

Fury1630 said:

Dave Brookes said:

For MOT testing:
Emissions are based on the age of the car or the age of the engine whichever is older.

http://www.motuk.co.uk/manual_730.htm

It's more complex than that, "home built" cars have theier own rules which say soething like visible smoke only unless a figure is noted on the V5.

Unless they've changed them again.

Maybe I should have worded it differently.
>>> Emissions are based on what it says on the V5 or the age of the engine, whichever is the most lenient<<<<<

That rule works for all the cars that I've built, Which state Cat test limits on the V5 (Which the car had to meet at IVA time even with a carburettor fitted) but doesn't need to meet cat limits later on. In my case it is all to do with Low Volume manufacturing as my pro built cars do not use engines from UK registered donor vehicles and are therefore tested as new/current engines even if the blocks were cast in the 1960s.

[rovermorris999]

My 2006 Riot on a Q came up on the MOT as visual check only. It has a cat but I'm thinking of removing it and taking it to Emerald for a remap to see if any more can be got out of it.

[Mr2Mike]

spyder dryver said:

From the same manual...
See note 3.b

http://www.motuk.co.uk/manual/how_to_use_page_one....

b. Vehicles having a Q plate registration when presented for MOT are to
be treated as being first used on 1 January 1971


Is this the latest manual that we are both quoting?

The "Q" plate "visual smoke check only" quirk still exists AFAIK.
I have just found a document that suggests that cat removal will only result in a fail on a vehicle that requires a FULL Cat Test. Page8 Sect.7
So not "Q" plates then.
http://www.dft.gov.uk/vosa/repository/MoT%20-%20Is...

The the MOT computer system presents the tester with emission limits when the registration is entered, then those limits are used for the test. If no limits are presented, then the MOT manual describes the fallback procedure.