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Discussion Starter #1
Hi all,

This is probably a daft question to ask but I thought I would go ahead and ask it anyway.

I am currently working on a 2002 MG TF, which has a couple of issues, but hopefully it will all be worth it in the end.
Anyway, I bought the car privately and was aware that it needed work to get it road worthy. The previous owners have clearly modified it over the years and it has a stainless steal exhaust system but the cat has been removed.
The car currently has no MOT but I aim to book it in for one as soon as I have sorted out the wheels and brakes.
I don't know how long it has been used with the cat missing but I was told it has an MOT recently and I am pretty sure the cat has been off it for a while.
Could the car pass an MOT with no catalytic converter do you think? Is there a way of modifying it so that the catalytic converter is no longer required?
I doubt there is but I'm sure there are people on here who know a lot more than me about these things
 

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mg_tf
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245 Posts
I belive that technicaly you do not have to have a cat, but the car must meet the emmision requirements for it's date of manufacture and without a cat it will not.
There should be a short "de-cat" pipe in the exhaust that can be swaped out for a cat to pass the MOT test and swapped back in afterwards if that is your thing. That may have been done in the past. Some say that this will release vast amounts of extra power. 馃ぃ
This is the rule book, the annex for MG is on page 141.
 

Registered
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303 Posts
Hi all,

This is probably a daft question to ask but I thought I would go ahead and ask it anyway.

I am currently working on a 2002 MG TF, which has a couple of issues, but hopefully it will all be worth it in the end.
Anyway, I bought the car privately and was aware that it needed work to get it road worthy. The previous owners have clearly modified it over the years and it has a stainless steal exhaust system but the cat has been removed.
The car currently has no MOT but I aim to book it in for one as soon as I have sorted out the wheels and brakes.
I don't know how long it has been used with the cat missing but I was told it has an MOT recently and I am pretty sure the cat has been off it for a while.
Could the car pass an MOT with no catalytic converter do you think? Is there a way of modifying it so that the catalytic converter is no longer required?
I doubt there is but I'm sure there are people on here who know a lot more than me about these things
The car by law must have a catalytic convertor fitted for it to pass its MOT. If one is not present it is an automatic fail.
 

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'06 MG ZR +120 (HQM) '04 MG ZR 105 (IAB)
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9,303 Posts
The actual wording in the MOT testers Manual is:

8.2.2.1.(a) Emission control equipment fitted by the manufacturer missing, obviously modified or obviously defective - Major.

.....which would suggest that you would only get away with a decat if it was not obviously apparent that the cat had been removed and the tester doesn't know that the MG would have had one fitted originally.

If the manifold for the TF is the same as the one for the K series ZR (and I think it probably is), there should be a catalytic converter in the manifold as well as the one in the main part of the exhaust, so 'a' cat will still be fitted and I would expect it would still pass the actual emissions test. This used to be how folk got away with having a decat at MOT test time, but since the wording of the criteria has been updated, I am not sure that you still can use that reasoning?

The suggestion above by Steve_G is probably the best compromise - to have a bolt-in decat pipe and a bolt-in cat that can be fitted in place of it prior to the annual inspection. A decat has always been a popular mod for increasing power and sound, but without any really reliable evidence of any great improvements in the power part of that!

Removal of the main cat will usually result in the MIL being illuminated in the dash - you need to check that this has been properly resolved by fitting of a MIL eliminator or other hidden means other than having simply had the bulb removed from the dash as the testers manual reasons for rejection also now includes:

8.2.1.2.(h) Engine MIL inoperative or indicating a malfunction - Major.
 

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mg_tf
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427 Posts
I have read, but have nothing to back it up, that these engines run so clean they will virtually pass an emissions test with no cat. One of my earlier cars had effectively de-catted itself, when I removed the cat there was nothing inside, I assumed it had disintegrated and been blown out of the exhaust, it鈥檚 possible this was a cheap de-cat done by the PO but I鈥檓 sure it passed an MOT in this state.

On your year of car, I believe I鈥檓 correct in saying there鈥檚 only 1 O2 sensor and it鈥檚 before the cat, later cars had 2 as a check that cat was working, so I鈥檓 not sure having no cat on your car would illuminate the EML light.
 

In the Garage
MG TF
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33,040 Posts
All MGR TF鈥檚 have two sensors but one CAT, so there are no pre-cats in the manifold presumably because the TF wasn鈥檛 sold in countries that mandated the fitment of pre CAT鈥檚.
 

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mgf
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839 Posts
I bought a cheap cat for about 拢60.00 and it failed on emissions the following year so I bought another cheap one and it passed but the following year it passed on 0.29 when the limit was 0.30 so I knew it would'nt pass this year. bought a cat for 拢150.00 from Rimmers and low and behold emissions were 0.00 could'nt believe it as I thought the engine was running very rich and after 130,000 miles it was very fumey,yet a new cat and we're all clean and green again. moral of the storey stay away from cheap CATS and get a dog.:LOL:
 
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