Replacement catalytic converter for the S8

[ainarssems]

What's the mileage on yours Adrian? IIRC it fairly low so wondering why it has disintegrated.
Mine is 19 years old now, 142k miles, I have had it for last 8.5 years and as far as I know cats have never been replaced. Emissions have steadily improved over the years I have owned it. MOT test limits are 0.3% CO and 200ppm for fast idle and 0.5% CO for natural idle. It started with something like 0.01 % CO and about 30 ppm of HC, last 2 MOT's it was doing 0.00 CO in both fast idle and natural idle and HC was just 8ppm at fast idle.

Maybe PF cats were better made then cost saving cut in for PF so might be an idea to fit second hand PF cats if they fit physically, of course you would need to find a way to fit after cat lambdas as PF never had any.

[Adrian E]

Originally Posted by ainarssems

What's the mileage on yours Adrian? IIRC it fairly low so wondering why it has disintegrated.
Mine is 19 years old now, 142k miles, I have had it for last 8.5 years and as far as I know cats have never been replaced. Emissions have steadily improved over the years I have owned it. MOT test limits are 0.3% CO and 200ppm for fast idle and 0.5% CO for natural idle. It started with something like 0.01 % CO and about 30 ppm of HC, last 2 MOT's it was doing 0.00 CO in both fast idle and natural idle and HC was just 8ppm at fast idle.

Maybe PF cats were better made then cost saving cut in for PF so might be an idea to fit second hand PF cats if they fit physically, of course you would need to find a way to fit after cat lambdas as PF never had any.

Hiya

Just passed 70k miles within the last couple of weeks, so yes very low for the age.

Cats failing is usually down to thermal shock or physical impacts, so either driving through flood water, or having a mechanic belt something too hard with a hammer could be enough to damage one. The nearside one is perfect still, but that's the one that failed on Andrew's....

The other possibility is engine related issues poisoning the cat. When the plugs were done very recently it turns out I'd been driving around for the last 5 years with 1 plug loose. That might've been enough to cause the cat to fail.

The problem for us is that the AVP and one other engine code fitted in the last 18 months of production are different to even earlier facelift cars. They are tucked in pretty tight, but without seeing ones for other engine codes from a facelift it's difficult to know if they could be made to fit.

Manufacturers have got wise to the problems caused by having cats under the car - they're now close-coupled to the manifolds because they avoid thermal shock up there, plus they light off more quickly too.

MOT testers aren't known for doing all they should with emissions testing - in theory with dual exhaust they should test both and take an average. I've never seen it done! My wife's car has 4 tailpipes (all connected to something, unlike Golf Rs!) and they definitely didn't on that!

[HPsauce]

Originally Posted by Adrian E

Just passed 70k miles within the last couple of weeks

Mine was rattling away when I bought the car at a lower mileage than that. But I factored it into the price and bought OEM - quite a bit later.
As for MOT's, it passed them all with flying colours, even with one cat doing nothing!

[Adrian E]

Mine passed in early September with flying colours, and given yours had gone for a long while after purchase without spectacularly failing I thought I'd be OK running it like that for years.

Given I believed I'd sold my car in theory, but will now need to start marketing in earnest now I haven't, I knew I couldn't leave it when it got a lot worse in a short period of time. I'm not the sort of bloke to sell a car with a known fault and it'd make it almost unsaleable without heavy discounting reflecting the OEM cost.

[Goran]

In the meantime, give it a blast with open pipes and make sure you record it and put it up on youtube



Something like this:

https://www.youtube.com/watch?v=KkglRtuqDt8

[ainarssems]

MOT testers aren't known for doing all they should with emissions testing - in theory with dual exhaust they should test both and take an average. I've never seen it done! My wife's car has 4 tailpipes (all connected to something, unlike Golf Rs!) and they definitely didn't on that!

They only need to test both sides if the sides are not connected with H pipe or X pipe. On A8 or S8 it is enough to test just one as they are connected with H-pipe. Also on true dual system where pipes are not connected I though if one side is over limit it is a fail, they do not take average, just the highest of 2 readings.

[Adrian E]

Well I managed to package both cats into a bicycle cardboard box and ship them via UPS and xxxxxxxxxx for just under £30 on Monday. They've been received today and I've paid the invoice via IBAN now I've had the total confirmed for refurbishing them both.

With exchange and processing fees from my bank the refurbishment and return shipping has come in just under £720

Not sure when they'll be shipped back to me - I suspect it will mostly depend on how long the payment takes to reach them, rather than the actual work!

ETA - have removed the reference to the company I used for shipping. They have 'hero' in their name but I cannot recommend their services, based on the speculative invoice for an extra £50 that they've sent me after the fact, claiming I misrepresented the dimensions of the box after an 'audit' by UPS of my parcel. Funnily enough UPS have confirmed they've done no such thing...