Emissions MOT failure

Technical Area Engine, Transmission, Exhaust etc
1
  1. My model of MX-5 is: 1.6 (90bhp)
  2. I’m based near:Huddersfield
  3. I’m looking for technical help or recommendations on: emissions

Hi all

I have just had an emissions failure on my MOT. I had a blowing exhaust which has now been repaired but the emissions failed again.

I was told to put in Redex, premium fuel and give it a run (which i did this weekend putting on 400 miles for the anniversary show) .

Just awaiting another emissions test - has anyone any recommendation’s or ways of tuning the car to ensure it passes as servicing these days doesn’t seem to include any tuning whatsover!

Many thanks

Jason

2

Forgive my ignorance but does the car have a cat fitted? Think you have done the right sort of things. Maybe check that the air filter is clean. Run some more premium fuel through it and give it a good “Italian tune” before you present it for its MOT

1 Like
3

Thanks for the reply! Air filter replaced and service - has cat - failed again - they have offered for me to drive in straight from fully warmed up run - any other ideas would be welcome - things to check before I go in etc. thank you

4

Which element of the emission test did it fail? What are the readings?

5

Check the AFM that’s what caused ours to fail a few years back. Also ours is 1990 1.6 and V5 stipulates %CO 3.5 & HC 0.12 I think it is tested differently than it normally would be, others on here will probably know more. Edit … just checked the last MOT and states “Non-catalyst equipped vehicle” even though it has a cat so perhaps you are having the wrong test?

6

Don’t know this time but first time the hydrocarbon reading was shooting up when revving

7

It’s 1994 so has a cat - I also have a 1990 model which has a cat and that sailed through - although I’m thinking of removing the cat from that one

8

High hydrocarbons indicates unburnt fuel, misfire for example. Was that the only failure?

9

Yes sir

10

Thanks all - took the car down motorway in 4th holding 4,500 revs for a good few miles - called MOT place to expect my arrival with a warmed up car. Passed

2 Likes
11

Result

1 Like
12

Well, almost last year. Friendly tester reported orally that he struggled to get result within limits but did so eventually suggesting on basis of only one cat visible mid exhaust that perhaps I had fitted a Sports Catalyst. I did not dis-illusion him but to help next month in addition to the pre test Italian Tuned Up I shall add bottle of Cataclean snake oil as heavily advertised in February issue of Soft-Top OC magazine. It would be nice to imagine that such publicity implied some degree of approval but I guess this as ever is for Caveat Emptor :crossed_fingers:

13

Please report back as I suspect I am not the only one that would appreciate it.
:heart:

14

For the record, put one bottle into quarter full talk so about 10 litres, then ran fast for about 100 miles before MoT - passed with no advisories so I didn’t ask any questions and will do same thing next year :+1: Whoopie

1 Like