Top Tip - MOT Emissions

Technical Area Routine Servicing
2

My 1995 mk1 MX-5 (Eunos) went in for its MOT this week, and failed on emissions.  

A forum member mentioned to check that it was tested as an import - which I did, and it passed.  A little bit of knowledge that saved me a small fortune in garage bills!

Just in case anyone is in a similar position, as I understand it this is how things work…

 - For an MX-5 the MOT emissions level for CO2 is 0.3 - in my case the CO2 was 1.2.

 - As the Eunos is an import, it’s unlisted in the offical MOT manual, and so it gets an MOT emissions level of 3.5.

It seems that not all garages know about this, or you need to point in out in case they miss it.  

3

I think the tip to bear in mind is that not all MoT testers are MX5 spotters, and couldn’t tell the difference between an MX5 and a Eunos if it ran over them. So when the machine says ‘what car is this?’ he’s probably going to guess at MX5 first off. Sure, if he looked closely he’d see the badges, if he knows what they mean, but with 10 cars to do today and 50 this week, he probably won’t.

So if you have a (fairly) unusual, imported, but pretty much identical version of a UK car, don’t assume that the tester knows as much…tell him first, then he won’t have to waste his time and yours on doing the wrong test.

4

Great tip, 

i am wondering if there is difference in the set up between the UK and import cars? Or should an import be able to pass the uk car test? 

What I am getting at is if your car failed the uk test, is it running badly enough to warrant investigating with a view to getting it running better? 

Just a thought!! 

5

 Slight difference in the ecu

 

No EGR on a Roadster

Smaller Cat on a 1.8 Roadster

 

So no it won’t pass a UK emissions test

 

 

PS it’s a Eunos Roadster: Eunos is a brand, like Mazda and there are quite a few other models

6

Fair enough,  learn something every day Thumbs up

7

I disagree, a Roadster in a good state of repair will still pass a UK emission test.

EGR is to reduce NOx which is not measured on an MOT so has no bearing on the result. EGR wouldn’t be operating at fast idle ayway. The ECU would still be mapped to run the engine stociometrically at fast idle so the catalyst is working at it’s optimum.

 

8

 A short cat on a 1.8 is very marginal, that is why bigger cats were introduced

 

A 1.8 with a good short cat will JUST scrape through  ( my Cal runs a short cat) but the cat needs to be hot.

 

Problem with a lot of MOT is that the car is looked at before emissionsare tested. Where as if it fails on only emissions these are tested straight away when it arrives hot on the retest

9

Does this mean that I could de-cat the exhaust and it would still pass?

10

 My UK spec Mk1 1.8 failed last week on emissions, probably through lack of use over the winter.

Some fuel additive/ engine cleaner and a long hard run sorted that out.

Runs better now tooBig Smile

11

We failed emissions today too Confused. 

A revvi blast up and down the lanes in 2nd to get the cat working hard and hot, and straight back onto the machine did the trick Big Smile.

 Other than that, passed with flying colours for another year Dancing

12

 Peter - in theory yes, it should.  But yours being a '95 could be close.  Pre ‘92 (I think)Eunos’ with a decat have no problem (mine never does).

13

 All about this in the FAQ (button at the top)

1 Like