Mazda Mx5 NC Mk3 Miata Manifold de-cat failure MOT Fail

[@Mx5modified]

What centre pipe do you have? I believe you can keep the standard centre cat and should still pass the emissions with a decat manifold.

[@jackos5s]

It’s the standard cat buddy, I’ve only changed the back box and manifold, the back box passed last year but now I’ve put the manifold on it failed

[@Mx5modified]

@@jackos5s oh that’s not good! I know my can fail from removing a cat but first I’ve heard from it failing because of the emissions

[@jackos5s]

I know I’m gutted, apparently it was really high on the emissions I even tried to get it down with a ECU re-map. According to the MOT station MOT rules changed this year 🤷‍♂️

[@Mx5modified]

@@jackos5s have you checked to see if your mid pipe cat is okay? I’ve heard running a 200 cell midpipe you can still pass emissions with a decat manifold. Unless the rules have changed? How did you find putting the old mani back in?

[@jackos5s]

That’s certainly worth exploring buddy, the car is hold up in the garage at the moment until April as I have to do a bit of welding on the jacking points as well. I might just invest in a mid pipe cat because I think it’s still the original! Fyi great content on your channel 👍👍

[@alfzeller9859]

What a shame after the effort and expense. That’s a bugger - feel for you

[@jackos5s]

Thanks Alf 👍 not sure what to do next! Just leave the old one on or swap them back over once I get the MOT test done!

[@dss199]

@@jackos5sI was told adding a additional cat to the midsection is enough

[@safety_squints]

find an MOT tester who might “accidentally” emissions test the wrong vehicle

[@dss199]

@@safety_squints hard to do apparantly these days

[@jackos5s]

lol 😂 great idea, with my luck I’ll probably end up paying more

[@WardyTechnical]

How far were the emissions off by? Just wondering with an 'Italian tune up' and some fuel additive before the test, you might be OK! As I know of quite a few cars with aftermarket manifolds and the OEM mid-pipe that pass.

[@jackos5s]

Great idea ☺️ the MOT tester said it was really high 🤷‍♂️so not sure of the numbers. Would it be on the MOT fail sheet?

[@WardyTechnical]

@@jackos5s You used to get the figures on a print-out, but not sure if they do that any more? It should certainly be recorded, so you could ask the tester to look them up for you. The MoT fail just records the reason, in terms of the category the fail was in.

[@jackos5s]

Great idea I’ll give them a shout and see what they say 👍

[@peterludlow9847]

What about putting a sports cat manifold back in instead of the restrictive standard one.

[@jackos5s]

Peter, I’d absolutely love to do that if the budgets allowed. I’d totally recommend to anyone to do this

[@peterludlow9847]

@@jackos5s I won't to change my manifold at some point but car is my daily so definitely need sports cat one. BBR would be my choice but think they are £800 so won't be this year got lot on and need to save for that. The other thing is getting the will power to do it myself heard a lot of stories it's pig of job and I can't afford to pay someone to do it. BBR also say u can fit it without a remap on standard car which is a bonus.

[@jackos5s]

They are a pain in the backside and if you’re doing at home you’re going to need two days, but could be done in one if nothing breaks and it all goes well. I have literally just put my old one back on and it took me no more than 1.5 hours. Even with a cheaper manifold it’s definitely worth doing I have no regrets really. Just a pain swapping them around lol

[@chrisbaxter5041]

Wonder what condition the mid cat is like

[@jackos5s]

That’s a good point, however it doesn’t look too bad. Not sure if it’s original or not