Has anyone....
 

Any experience with after market catalysts? The flexible joint on mine is starting to look decidedly second hand...As are the pipe to Manifold studs which are definitely going to go “ping” the moment I even look at them with a spanner :(

I’m going to need a new one at some point In the near future, but are aftermarket units actually capable of passing the MoT emissions test?

I’ve put a request in to the forum sponsors for a unit if they have one but there are some attractively priced new units out in the big wide world. However there’s no point getting a new one if the catalyst parts are ineffective. So do off the shelf pattern parts work? Or do I avoid them like the plague? Answers on a postcard.

I've had sports cats on mine for around 9 years, they pass MOT fine but they do throw the EML light occasionally, easily sorted with a cheap code reader from Ebay

I think David’s has aftermarket sports cats as well and he also has the EML light issue. But, IIRC, the fitter can put in little spacers for the sensors to take them out of the flow of the exhaust and this, apparently, stops the light coming on. One of my cats is starting to rattle, so I’m interested to see how you get on

I had after-market sports cats fitted a couple of years ago too. Audi quoted £2,500 for a pair of OE cats (not inc. fitting) when my old cats first started rattling. And by the time the rattle had gotten much worse, just a few months later, the OE cats were NLA, so I had no choice but to look at alternatives. I decided to go for a custom stainless steel exhaust in the end, complete with after-market cats. More info here:
http://forum.a8parts.co.uk/showthread.php?t=14489

I've had no problem with the exhaust passing MOTs -- I believe the important thing is that the cats should be 'E' marked/approved, which mine are. I do have to occasionally reset the EML (usually after being stuck in slow moving traffic for a long time), but I can do that by the roadside in seconds using my phone and OBDeleven device. It's a slight annoyance but a fairly rare occurrence.

It's worth noting also that you may be able to sell your old cats to a recycler, even if they're badly rattling (like mine were). I got £220 (£110 each) for mine.


EDIT: Zaustworx video of my car attached below:

And this should be a direct link to my car on Zaustworx's FB page: https://www.facebook.com/ZaustworxCu...9764221425173/

Good running engine should pass emissions even without cats, obviously cats are required by the rules so would still fail MOT even if it passes emissions test

If the cats are I would just cut out flexi piece and weld a new one in. Cheaper and you get to keep original cats.

I am pretty sure an FL D2 won't pass the age-appropriate appropriate emissions test without cats - I've tried it. Big Red (2002) has the pre-cats only which keep the ECU happy, but needs to be roasting hot to pass just barely within spec without the main cats. Ditto Mike's 4.2 Allroad (2005?), which also has pre-cats so no EML, but empty cans for the main cats. That missed the limits by a sizeable margin IIRC so we're fitting some Magnaflow E-marked cats to it before its MoT. Both of those engines are in good health and running well.

An early PF might pass without cats I guess, although I think it still supposed to have them.

An exhaust/Cat fitting business suggested to me a few years ago that probably the most economic way out of this issue was to replace the dead cats with a couple of E marked aftermarket items for a 2.0L Mondeo!

A quick search suggests that would be 55mm diameter so would work ok for the 2.8 or 3.7, but would be a bit small for the S8 which is 60mm.

One of my pet subjects, this......

There's a thread on here about the reconditioning of my OEM cats, by a German company, using metal substrate cats that are better than OEM quality. Cost to refurb 2 was less than one OEM cat (when they were available),but it is a bit of a mission to do.

http://forum.a8parts.co.uk/showthrea...ight=converter

The vast majority of low end replacement cats are designed to have a life of x2 MOTs - the one it just failed that's forcing you to replace the cats, plus the next one to scrape through, so the warranty on the cat has expired before what little precious metal has actually stuck to the poorly made substrate from India has gone astray. This assumes the washcoat was actually up to spec in the first place, and that the company that made it did proper 'worst case' testing amongst the 500-odd models the cat itself can be canned to work on.....

The only exception to this is German 'Blauer Engel' parts, which you'll struggle to get in the UK as the market favours the £200 options over the near-OEM level parts.

The issue with 'sports cats' is that they're usually a low cell count in order to make them more free flowing. They could work, if only they made them with sufficient wash coat to counter the more free flowing nature. They do a job, but basically the dodge ref spacing out the lambda sensors is so the probe isn't 'sniffing' as instantaneously as the ECU would like, so it then misses the spikes in emissions that the cats can't deal with.

The UN regs need re-writing to make aftermarket products closer in quality to OEM, but for the moment the race is to the bottom in terms of price and therefore quality....

Sports cats might be a slight excess for a 2.8 :D Without the impending MoT emission test I couldn’t say the cat is ok but it passed the last test ok and it’s only done a few thousand miles since then. The flexi is the impending failure however, it has lost all its wire reenforcement and is definitely looking in serious distress at the rear joint. No dice with forum sponsors so it looks like a journey into replacement land. Only way to find out if a weld in flexi section is a go is to remove the cat (which then needs new manifold studs because they are eroded to nothing) and go from there. But the price of a “cheap” replacement and the fact it’s all coming off for a flexi might just make throwing a new one at it and seeing what happens the easier option! Or I could just hope the old one just hangs on....it’s lasted 20 odd years...right?