MOT emissions fail after secondary cat delete

[flango]

I also wonder about the longevity of some aftermarket sports cat - even if it gets through the first MOT, how many subsequent years will it pass for.

I would be erring on the side of welding the original cats back in myself as long as they do a reasonable job of it. It should be pretty easy as the could just sleeve it either end.

There were cars we did mostly Subaru and EVO I admit, but the sports cats on those things would be only good for 18 months - 2 years max. This is in line with my own experience on SWMBO A8 fitted 2 x sports cats and new O2 sensors, flew through MOT Immediately, 12 months later still passed but had dedteriorated with higher emissions readings, 20 months later both cats had failed miserably and these were high end cats not the cheap ones you can pick up for a couple of hundred quid

 

[BTB 500]

Hmm ... thanks guys. Food for thought.

Will have a look at the current emission figures (no cats) to see how big the difference is compared to last year's MOT.

Incidentally, far from trying to sell me a replacment OEM system the guy at the dealership (service team leader) suggested getting a bolt-in set of cats that could just be put in at MOT time!

 

[IanA2]

In view of the other Ian's observations, I'd be inclined to get the originals put back on.

 

[Sp!ke]

In view of the other Ian's observations, I'd be inclined to get the originals put back on.

Problem is though BTB is now addicted to the noise his car makes.

 

[IanA2]

Problem is though BTB is now addicted to the noise his car makes.

Addictions can be expensive.....

 

[DSB SL AMG]

Easy then, you now have a solution

Hmm ... thanks guys. Food for thought.

Will have a look at the current emission figures (no cats) to see how big the difference is compared to last year's MOT.

Incidentally, far from trying to sell me a replacment OEM system the guy at the dealership (service team leader) suggested getting a bolt-in set of cats that could just be put in at MOT time!

 

[BTB 500]

Unfortunately I can't be bothered with swapping bits of exhaust over!

I would be reluctant to go back to a standard setup ... the whole point of the changes was to get a bit more noise. But obviously I want to be able to get through the MOT!

The failed emissions test ticket from Tuesday doesn't give any of the actual readings, which is weird?!

With the M-B cats it was well under the limits last year:

Fast idle CO 0.06 (limit 0.2)
Fast idle HC 36 (limit 200)
Fast idle Lambda 1.011 (allowed range 0.97-1.03)
Natural idle CO 0.00 (limit 0.3)

So I'm hoping that sports cats will be OK, but I will discuss with the exhaust place first and keep the original cats just in case.

 

[IanA2]

Unfortunately I can't be bothered with swapping bits of exhaust over!

I would be reluctant to go back to a standard setup ... the whole point of the changes was to get a bit more noise. But obviously I want to be able to get through the MOT!

The failed emissions test ticket from Tuesday doesn't give any of the actual readings, which is weird?!

With the M-B cats it was well under the limits last year:

Fast idle CO 0.06 (limit 0.2)
Fast idle HC 36 (limit 200)
Fast idle Lambda 1.011 (allowed range 0.97-1.03)
Natural idle CO 0.00 (limit 0.3)

So I'm hoping that sports cats will be OK, but I will discuss with the exhaust place first and keep the original cats just in case.

Good thinking..

 

[flango]

Remember fitting sports cats will also change the noise from what it is now, it will quieten it down but not to the levels as the original set up.

 

[BTB 500]

Yup I'm assuming sports cats will be a little louder than the M-B ones were.

It's a shame in a way as the current setup (no cats) isn't excessive by any means - I guess the back box is reasonably efficient. I'd be reluctant to open that up and start attacking the baffles as it's a genuine AMG one (£££) - if necessary I could follow Sp!ke's route and look out for a cheap standard rear box and experiment with that.

 

[BTB 500]

So just to close this off.

Car went back on Tuesday to have 200 cell sports cats fitted. I was assured they would be OK for the MOT, and in fact they provided an emissions test readout (they are also an MOT station) as part of the process. Back to M-B Guildford for a (free) re-test today and no problems

As expected the sound is somewhere between the original setup with M-B cats, and how it was with no cats at all! Sounds nice when driving ... some noticeable rumble at low speed which was absent with the M-B cats. It's also lost the slightly annoying metallic rasp that the non-cat system had at about 1500 rpm.

One slightly odd thing I noticed is that the new cats are towards the rear of the system rather than straight after the downpipes. Not sure of the reason for that but doesn't seem to cause a problem.

Just after giving the car a wash today:

[YOUTUBE HD]5FLwN7hma4c[/YOUTUBE HD]

 

[IanA2]

Was the wallet damage excessive?

 

[BTB 500]

£475 in total.

 

[IanA2]

Gosh....that seems very reasonable indeed

 

[C43AMG]

Sounds okay Bill.

 

[DrNick]

Old thread resurrection, but its relevant!

Had the two rear cats deleted on my 500 last week, leaving only the front two. Car passed MOT with no comments. Coincidentally also had to renew insurance this week - declared exhaust mods, and the lowest renewal quote was actually £150 less than the current insurers offer. New quote £265 which I think is reasonable with legal cover and breakdown recovery, although I hope not to use it!

 

[ALFAitalia]

Surprised that they offered cover at all....what you admitted to is illegal to drive on the road and attracts a £1000 fine.....emissions passed or not!! .........so I would have expected them to decline cover at all. Result on the price though!!!

 

[DrNick]

Surprised that they offered cover at all....what you admitted to is illegal to drive on the road and attracts a £1000 fine.....emissions passed or not!! .........so I would have expected them to decline cover at all. Result on the price though!!!

There is obviously a lot of discussion on t'internet about legality or otherwise. The MOT tester guidance on the government website says its ok as long as the car was first used before 2002. This is an R129 so that applies. Here is a section from the website

Flowcharts 1,2 and 3 don't tell you much other than test it to a base standard unless the actual engine is in the database, then test to that standard. You can look here if you are really interested.
MOT inspection manual: cars and passenger vehicles - 8. Nuisance - Guidance - GOV.UK

I haven't read the whole thing but this seems to be the salient part. If your car is newer than 2002 then you cannot tinker.

This obviously assumes that the MOT test is the definitive rule. There may be other rules that lead to fines. The MOT inspector can't issue fines that and I'm not aware of any other rules, but then I'm just a motorist!

 

[DrNick]

So here you go. Modifying your vehicle’s emissions: the legal, safety and health implications

So there is a £1000 fine, but only if the vehicle does not comply with the emission standards it was designed to meet. This is defined by the MOT test.

So no £1000 fine and no illegality in my case. Happy insurance company as its been declared.

 

[ALFAitalia]

You are not allowed to remove any factory fitted emissions equipment... illegal and an MOT fail with the same fines as above. But yes you are unlikely to be caught.

From the MOT testers manual.

a) Emission control equipment fitted by the manufacturer: missing, obviously modified or obviously defective. That's classed as a major defect and should be an automatic MOT failure.

...it matters not if it passes emissions or not.