Manky Monkey Motors

Technical Section => General Tech => Topic started by: Olds on October 11, 2018, 06:46:50 AM



Title: D'oh ! MX5 Emission AGAIN !
Post by: Olds on October 11, 2018, 06:46:50 AM
Last year my daily failed the MOT on CO emissions and I discovered the catalytic converter had disintegrated internally so I fitted a new one. Hey presto CO down to 0.04%
This year it has failed it's MOT for, yep as the title states, sodding CO emissions. ???

MOT tester was baffled. He could see the new exhaust system but the readings he was getting suggested a decat had been fitted. So it looks like the cat I bought last year has failed in some way. >:(


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: terry t on October 11, 2018, 08:33:05 AM
I would get it checked at another mot station. just ask them to do an emission test


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Archie on October 11, 2018, 06:30:24 PM
There are problems with some of the cheaper cats from euros etc. If you’ve got the receipt still it’ll be under warranty.

Might be worth a cataclean treatment goop and get it red hot before retesting it


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: spanners on October 11, 2018, 06:50:08 PM
What year is the MX5


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Olds on October 12, 2018, 04:43:03 AM
Terry. Unless their equipment is faulty I can't see the point. They had no incentive to give false reading as they know I wouldn't get them to change the cat and it was a no pass no pay MOT. I also ought to replace a brake line that's  corroded.

Archie. Yep I heard that and am looking for the receipt. Thought about a cleaner but have decided to just replace the damned thing. Cheaper than a tank of fuel plus cleaner. Don't intend to keep the car so I've got a cheap cat coming.  At least it should be easy to change.

Mike. It's a 2000 car.



Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: terry t on October 12, 2018, 07:02:31 AM
Terry. Unless their equipment is faulty I can't see the point. They had no incentive to give false reading as they know I wouldn't get them to change the cat and it was a no pass no pay MOT. I also ought to replace a brake line that's  corroded.

Archie. Yep I heard that and am looking for the receipt. Thought about a cleaner but have decided to just replace the damned thing. Cheaper than a tank of fuel plus cleaner. Don't intend to keep the car so I've got a cheap cat coming.  At least it should be easy to change.

Mike. It's a 2000 car.



Olds I'm not suggesting for one minute they where trying it one. it just may be a faulty reading at the end of the day its only a computer with sensors fitted and tested yearly   


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Olds on October 12, 2018, 07:15:22 AM
Don't think the equipment can be that far out as other cars tested were fine. They tried three times with almost the same results each time. It's not just failing it's failing big time.  0.65% CO, a fail is anything over 0.30%  Last year I had similar results with a cat that had no core left so pretty certain the cat has failed. HC readings are fine.


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Olds on October 13, 2018, 07:47:57 PM
New cat fitted so hopefully that will keep Mr MOT happy. Had to do it single handed and by that I don't mean on my own, but literally with one hand as I have a 'frozen' shoulder and couldn't use my left arm. Can't see much wrong with the one I've taken off and the very light coating of soot in the pipe suggests fueling must be OK.
Also made a up new rear brake pipe and glad that I did. When undoing one of the connections  the old pipe broke up !
I have checked the other rigid pipes and they all seem fine


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Manky Monkey on October 13, 2018, 08:01:53 PM
Hope the shoulder sorts itself out mate.
So how old is this Mazda of yours then? What's the average lifespan of a cat? Is it like schrodinger's cat -you don't know if it's alive or dead until you open the box?


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Olds on October 13, 2018, 08:27:52 PM
The car's 18 years old and I think the cat and exhaust I removed last year may have been the original.
Unlike Schrodinger's cat where once you open the box you know it's very definitely dead (or not  ???), this type of cat you can't tell by looking at it. Unless of course it's like the last one I had where there was no gut's left in it.


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Manky Monkey on October 13, 2018, 11:05:13 PM
:)


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: poprodder on October 14, 2018, 02:03:23 PM
original equipment cats are ok, aftermarket are crap.
scrap dealers give way more money for an original, more precious metals in them. says it all.


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Olds on October 15, 2018, 10:41:27 AM
original equipment cats are ok, aftermarket are crap.
scrap dealers give way more money for an original, more precious metals in them. says it all.
Well they wouldn't have given me anything for my original one  :D

MOT passed this morning with no problems.
 Total cost for MOT, catalytic converter and brake pipe  £77 so not too bad.  :)

 


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Manky Monkey on October 15, 2018, 05:36:36 PM
So it lives for another year :)


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Olds on October 15, 2018, 06:27:18 PM
Unless something goes bang it looks like it might.  :D  


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: merv on October 16, 2018, 04:31:39 PM
Take the new cat of and save it for next year :D


Title: Re: D'oh ! MX5 Emission AGAIN !
Post by: Olds on October 16, 2018, 07:21:43 PM
Almost tempted to, but not going to keep the car another year. I bought it as a temporary stopgap till I found something else. That was two years ago !