- My model of MX-5 is: NC1800
- I’m based near: COLCHESTER
- I’m looking for technical help or recommendations on: __Emissions
Failed MOT on emissions what should i be looking at, The mileage is 117,000 plugs change at 104,000
Thanks
My NB failed this year on emissions and the garage found that the Cat convertor had disintegrated so i had to have a new one fitted
Sounds expensive.
got my MOT next week and i am worried about my emmissions!
fingers crossed!
i can really do without having to spend 1400 on the BBR catted downpipes and centersection for atleast another couple of months yet
Take it for a good blast just before it goes in the ramp…get some heat into it… apparently…
3 Likes
i know the fitters at my old job used trash all the transit vans in 3rd gear for 10 miles before taking them in for the MOT’s.
but thats not something i want to do to my mx5!
So what catalyst do you actually have on your car then? Providing you still have the rear cat then in theory at least you should still pass the basic exhaust emission test. You just have to hope that the tester does not realise or notice that the manicat has been removed because that is an automatic fail on the basis that the type approved equipment as been modified. Most testers will probably miss this point, just hope you are one of the lucky ones.
the downpipes and center pipe is still standard and as such i have both cats.
i have a nasty feeling that at 9 years old they might be knackered.
im planning to get the BBR catted down pipes as part of the super 180 kit and add the bbr center pipe at the same time but that wont be for about 3 months or so.
tho if forced by MOT i can dip into savings and do it sooner.
Then you should have no problems with your next mot on the basis that you were probably well within the limits last time ? 9 years should still see you through the current mot emissions test which is not actually that severe.
Tried that.
Best get the cotton wool out then… 
What were the actual emission readings?
Hi Robbie,
Are MOT stations obliged to give printout of results now?
If requested, should the test station provide a printout?
I always used to be handed a copy with MOT cert… but last couple of times nothing to show emissions results.
They were useful to have, to see how the results were trending over the years.
Cheers, Tim
Hi thanks for replying the readings are CO-------2.74 HC----835 ppm At fast idle test
CO----------2.60 HC-----1117 ppm At second fast idle test
Does the engine burn any oils? What’s the Lambda reading? I’m surprised the engine light isn’t on with those figures.
Hi no it does not burn oil don’t know the Lambda reading, no engine light on.
That’s a serious fail, possibly caused by over fuelling, even a modern engine with a busted cat should produce better figures than that.
What is the cars history, any changes and do you know what the previous mot emissions were? Have you checked for any OBD error codes? Difficult if not impossible to diagnose from a distance think you need to get the car to an mx5 specialist.
My thoughts exactly have booked it in to my local guy is very good with MX5s going in Friday i will let you know the results, Thanks for your help.