GR86 First MOT, Modified Cars, Future Emission & Noise Issues

My 2023 GR86 just had it's first MOT, and one of the advisories was;
"Catalyst Emissions Limit Only Just Met"
Mine is fitted with the GR airbox and a cobra un-resonated cat back exhaust.

I was quite surprised at the fact it was only just under the limit, I've not had it tuned after running those things so could that be an issue? (and does that mean I have to spring for the whole ecutek thing?)

Also, this is... worrying? if anyone is looking to maybe play with mods in future;
https://www.evo.co.uk/news/209071/c...with-uks-tuned-and-modified-vehicles-targeted

This is also interested considering a lot of mods seem to want to remove the cat;

https://www.evo.co.uk/news/206327/g...-down-on-loud-car-exhausts-not-just-emissions

Be interested to see what anyone else thinks, I was thinking of turbocharging mine at some point, but now I'm wondering if this hasn't harpooned that...

I have the same mods as you: Cobra Non-Res and TRD Cold Air Intake. There is no requirement to tune with either of these. Nothing was picked up at my MOT for emissions in March of this year when it went into the dealership, maybe take it somewhere else?

The new regulations will likely restrict a lot of 'dodgy' mods, especially as it could lead to the keeper being prosecuted in certain areas like emission system tampering (which was always illegal anyway).

Do you occasionally give it the beans? I was always trying to get the best MPG I could while commuting but gave her the old Italian tune up more often in the lead up to my first MOT. I've kept up the habit! If the revs aren't getting high enough often enough I believe carbon deposits can build up which negatively affects emissions .

Renzokuken86 said:

Do you occasionally give it the beans? I was always trying to get the best MPG I could while commuting but gave her the old Italian tune up more often in the lead up to my first MOT. I've kept up the habit! If the revs aren't getting high enough often enough I believe carbon deposits can build up which negatively affects emissions .

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That's interesting, I got it done at somewhere quite a way away as I was on my way somewhere else and it'd been sitting on the motorway cruising for an hour...

Sixtoe said:

That's interesting, I got it done at somewhere quite a way away as I was on my way somewhere else and it'd been sitting on the motorway cruising for an hour...

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An hour on the motorway wouldn't be enough to result in any significant build up, it would be constant motorway cruising at low revs over months. I was so focused on getting an average 35mpg according to the car on my commute, hit the target and since I've dropped it to 34.1mpg

The GR intake does move the position of the MAF, so it will impact AFR, its how some air intakes claim to make more power, not because they are better flowing but because they lean out the AFR, but in this case it shouldn't be by much, definitely not enough to alter the emissions that much, the short and long term fuel trims would take care of that.

Catalytic converters are very sensitive to temperature, maybe it just wasn't that hot when they did the emissions test?

ruled over by joyless jobsworths sadly.



Proposed changes to emissions regs and testing are a concern in general given the potential for an older bone stock car to fail.

Fuel quality, atmospheric conditions, test method could all impact results. Owners like myself who intend to keep the car forever could find themselves unable to source OEM replacements for parts which fail entirely or sufficiently to not meet regs.

It’s an absolute can of worms for all older vehicles modified intentionally or otherwise. I’ve no doubt it’s as futile as trying to hold back the tide but I filled out the gov.uk consultation form disagreeing to all proposed changes and voicing the potential negative impact to the public and motor industry as a whole.

This is very interesting, Ensuring my car passes emissions tests is why I have been so specific with my front pipe selection and ended up getting one custom made and shipped from the US. I'm taking mine over to an old friend's garage to get emissions tested next week in leu of it's first MOT. He used to build the cars for a drift team and he's got some crazy Japanese cars, so I hope it comes back with tread on the rear tyres still

Sixtoe said:

Be interested to see what anyone else thinks, I was thinking of turbocharging mine at some point, but now I'm wondering if this hasn't harpooned that...

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Without wanting to sound like an unpaid advertiser for JDL, their turbo kits have a 400CPSI cat in the downpipe, so might end up being the best choice for the emissions conscious UK GR86-turboer. apparently they're RHD compatible.

GRistopher said:

Without wanting to sound like an unpaid advertiser for JDL, their turbo kits have a 400CPSI cat in the downpipe, so might end up being the best choice for the emissions conscious UK GR86-turboer. apparently they're RHD compatible.

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That sounds really interesting, I'm wondering if it's going to force all UK tuners to do that as well anyway.
I'll be very interested to see how yours goes on the test