Decat exhaust - booking an MOT

bainbridge

bainbridge

bainbridge

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Hi Motors

The MX5 now has a decat sports exhaust manifold and the only catalytic converter is in the mid pipe.
So with the maniverter gone she'll need to be warmed up to pass the MOT.

I've used the same garage for 15 years and he's also an MOT testing centre, the procedure is to drop the car off in the morning and either collect it when he calls or at the end of the day before he closes. So I've no way of ensuring the engine is hot.

What's the deal here? Do I drop it off late afternoon or can I simply drive to an MOT testing centre just before it's tested if I use a different place?
 
bainbridge said:
Hi Motors

The MX5 now has a decat sports exhaust manifold and the only catalytic converter is in the mid pipe.
So with the maniverter gone she'll need to be warmed up to pass the MOT.

I've used the same garage for 15 years and he's also an MOT testing centre, the procedure is to drop the car off in the morning and either collect it when he calls or at the end of the day before he closes. So I've no way of ensuring the engine is hot.

What's the deal here? Do I drop it off late afternoon or can I simply drive to an MOT testing centre just before it's tested if I use a different place?
Click to expand...
Emissions tests are always done with a warm engine. The operator can manually tell the machine the engine is up to temperature to which is why you'll sometimes see something like "coolant pipes hot" where you'd expect to see the engine temperature on the print out. Most will now use either an oil temp probe or OBD reading these days to verify the temperature
 
throw the dice...

it's technically an automatic fail by removing either cat - rules say something like "check a catalyst isn’t missing where one was fitted as standard" - one is fitted on the downpipe, so if it's not there then fail.... But, as has been mentioned many a time, they usually only check for the main one under the car.

If you've used the same garage for years and get on with them, then just ask them to make sure it's nice and warm 1st... ;)
 
lordrobs said:
Emissions tests are always done with a warm engine.
Click to expand...

Its not the warm engine that is the issue, it is the warm cat!

The mid pipe cat will prbablly be fine as far as emissions are concerned as long as it is in good condition. But it will need to be piping hot at the time of the test.

(Might one wrap it with exhaust bandage to keep it hot and improve its efficiency under idle/light load conditions??)
 
Technically and legally it should fail but that is down to the discretion of your tester. If you are friendly with them a quiet word about warming it before testing might be worth a go. If not there is not much you can really do other than cross your fingers......
 
With my old Scooby I used to book it in for the first test of the day, give it a good run before hand to warm the cat up and ask them to do the emissions test first .

Passed every time :)
 
Thanks for the responses guys.

I still have the old catted manifold so temporarily changing back isn't impossible but will be a complete arseache, what with having to shorten the wiring again for the o2 sensor, not to mention all the bits that have to come off to get at the manifold.

Am I right in assuming that if the car failed due to a missing cat, that info would be electronically recorded, so even if I then took it to a different MOT test station they would have to check for both cats?
 
Your main hope here on the visual check is whether the tester is aware of the differences between the NB1 and NB2 in that the NB2 has two cats Vs 1 on the Nb1
 
you've used the place for 15 years i'd be surprised if its in any way an issue,

give your tester a heads up regards the change and ask him to warm it right up.
 
This caught me out when I had a modded Golf R last year, assumed the exhaust was road legal so should pass an MOT, took it to kwik fit as it’s near work, they failed it on the emissions so I had to take it to the place that fitted all the mods and he said he just warmed it up properly and it went straight through.

Long and short is if you know the garage just ask them to warm it up sufficiently first?
 
233 said:
you've used the place for 15 years i'd be surprised if its in any way an issue,

give your tester a heads up regards the change and ask him to warm it right up.
Click to expand...

That's the problem with the new regulations, all oem emission control parts have to be fitted, so telling him about the decat would be asking him to fail the MOT.
 
DereksDontRun said:
throw the dice...

it's technically an automatic fail by removing either cat - rules say something like "check a catalyst isn’t missing where one was fitted as standard" - one is fitted on the downpipe, so if it's not there then fail.... But, as has been mentioned many a time, they usually only check for the main one under the car.

If you've used the same garage for years and get on with them, then just ask them to make sure it's nice and warm 1st... ;)
Click to expand...

Yeah, no. They never check. You literally can't miss the modification on mine. They are too busy admiring the engine.

Also haven't been to a place that hasn't warmed it up well. Even Kwik Fit.
 
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