Mine is falling apart inside and is definitely going to fail the MoT next time round (should have done this time really!) but I’ll be damned if I’m paying Mazda prices for one, and the standard (Bosul I think) aftermarket from my motor factor is still £130 ish. So I’d be surprised if a £50 one is any good, but you never know!
Yes, unfortunately I do need one - no hope of getting through MoT with a decat.
Trouble is mine was still working last MoT (good numbers), just can hear the contents rattling around inside so won’t be long before I leave it all behind on the road!
I bought a cheap cat from mx5 parts £115, didn’t last a year
so I replaced it with an even cheaper one and a silenced decat pipe. My new cat will pass the next mot as it’s only done 10 miles this year ( garage is 5 miles away)
Indeed I could get this cat, and a decat pipe, all for less than the mx5parts cat on its own. It means getting under the car twice a year, but it might be worth it to have an MoT-Day cat, and the rest of the year be a bit louder.
Tempting - as long as this cat does the job enough to pass the test…
It’s not that cheap - I sell a UK manufactured aftermarket cat for less than £45 with a 2 year guarantee, although the next day courier does make it a little more expensive. Cats often fail because of an engine fault. Any new cat fitted to a car with an existing engine fault, for example a misfire, will not last very long and will void warranty. Cats do wear out over time/use but before fitting any replacement make sure your lambda sensor is functioning correctly and the car is running without a fault. Most faults that cause a cat problem will manifest themselves in a substantial increase in fuel consumption(10 - 25%)
Mine is a uk 1990 mk1 i fitted a decat pipe yesterday i asked about m.o.t and he said i wouldnt need a cat on it has anybody got their mk1 uk 1990 passed mot with decat saves me swapping it every year
I brought a cheap cat from SFT; it needed replacing at the next MOT, but it was probably destroyed by the dying 1.8 engine I had (burning loads of oil). I have no idea where Sam Goodwin got the replacement cat from (probably SFT, the invoice indicates it was cheap), but its been fine ever since.
The material used to make the cats my suppliers use is generic. There used to be a choice between a ceramic or steel monolith but as far as I know type approved parts(for vehicles registered after 1/3/2001) are only available with a ceramic core. These ceramic cores are bedded in a surround of special matting. when you first drive the car after fitting a ceramic cored cat it is vital that you do a decent run to heat the matting up. It does a one off expansion to hold the core securely in place. If this is not done correctly ie. the cat is not heated up sufficiently when first commissioned, the matting will not expand enough and the core will become loose prematurely. This is doubly important with cars like Mercedes where there are two cats in series and extra heat is required to commission the rear cat cannister.
The cat will burn off most soot and other impurities but if too much descends onto the cat, it will produce a layer which stops the cat heating up sufficiently and for obvious reasons kills it. A misfire, for example with a faulty coilpack, causes unburnt fuel to be ejected through the exhaust valves onto the cat. This can cause the cat to overheat and the core to melt and block the exhaust or break up. MX5s seem to run rich generally and are prone to coil failures - good job the cats are cheap:-)
