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D2 - Fuel and Exhausts Everything to do with getting fuel into the engine, and fumes back out again

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  #1  
Old 17th June 2017, 10:49 AM
runman99 runman99 is offline
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Default A8 D2 4.2 32v 1999 Quattro Sport Catalyst converters?

Hi all, well seems that my 'cats' are on the way out. they are the original ones.

(Engine code ABZ)

RH - 4D0 131 701 AM Manuf 09-98
E18 022

LH - 4D0 131 701 T Manuf 09-98
E18 024

Trying to find aftermarket replacements.

HELP!
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  #2  
Old 17th June 2017, 11:13 AM
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David's8 David's8 is offline
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Whereabouts are you?
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Old 17th June 2017, 01:54 PM
ainarssems ainarssems is offline
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32V was in production until late 1998 so it seems like yours is a later registered early car. The cats on those earlier cars seem to be more reliable than later FL cars, the only case of failure that i remember of is with blown head gasket when coolant entered exhaust and contaminated cats. What are the symptoms that make you think they are on their way out? Not sure if there are direct fit aftermaket replacements available for these now. Most cost efective would probably be weld in universal cats.
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Old 17th June 2017, 02:03 PM
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Goran Goran is offline
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If it is the cats I would go for something from Germany, like this, with metal element rather than ceramic. These are 400cell.

http://www.ebay.de/itm/Sportkat-400-...-/321751735732

You could go 200 cell if your car is pre-facelift since you dont have post-cat lambdas.
http://www.hjs-motorsport.de/produkt...talysator.html

I had two similar to these on my previous S8 always passed emissions, now I have two of these on my current S8

http://www.turbozentrum.de/0/a-31960/

There are these too also HJS a bit cheaper

https://www.turboperformance.shop/do...s-bis-2600-ccm

Last edited by Goran; 17th June 2017 at 02:09 PM.
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Old 17th June 2017, 03:35 PM
Mossyboy1978 Mossyboy1978 is offline
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Hi Goran, how have you found these sports cats for performance and sound? Were they an easy ft/replacement? Mine are about to die and I don't really want to do a refurb or pay for new Ines from Audi.

Thanks

Mossy

Quote:
Originally Posted by Goran View Post
If it is the cats I would go for something from Germany, like this, with metal element rather than ceramic. These are 400cell.

http://www.ebay.de/itm/Sportkat-400-...-/321751735732

You could go 200 cell if your car is pre-facelift since you dont have post-cat lambdas.
http://www.hjs-motorsport.de/produkt...talysator.html

I had two similar to these on my previous S8 always passed emissions, now I have two of these on my current S8

http://www.turbozentrum.de/0/a-31960/

There are these too also HJS a bit cheaper

https://www.turboperformance.shop/do...s-bis-2600-ccm
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2002 S8 Aqua Pearl, entirely original apart from FE 20" OEM wheels and Milltek exhaust.

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Old 18th June 2017, 03:14 PM
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Goran Goran is offline
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Hi Mossy,

I cant comment too much about the sound, in both cases for both cars I had them done at the same time as getting a custom exhaust. The custom exhaust changes the sound much more than th cat. Although on the current S8 I did run catless on the stock exhaust system for a while, I just couldn't wait for the custom exhaust because one cat was rattling badly. From memory, it was not much louder catless, the stock exhaust is pretty well silenced. So if you just change the cats I doubt it will be much louder.
It should be a straightforward job, cut out the old cats, weld in the new. If the new ones are significantly shorter they may need a length of pipe same diameter as stock to lengthen it. Oh and yes on one side there will be a slight complication. Audi in their wisdom made one cat easily removable with a bracket joint just in front of the cat, but the other stock cat is a part of the downpipe with the pre-cat lambda sensor in it, so they may have to remove that whole pipe. Unless they can just chop it off and weld in a new bracket in situ?
The more expensive cats I posted should have the same entrance/exit diameter as the stock exhaust 61.5mm, the cheaper ones are a little bit bigger diameter at 63mm but hopefully that's not a big problem.

The 200cell cats should definitely release some performance, they are much less restrictive than the stock 400cell ceramic cats. It wont be much though, and you would have to dyno it before and after to get a sense of any increase in hp. I did dyno my car before I changed the cats and the exhaust but haven't had a chance to do another one after so I dont know if its gone up (or down)

I forgot to mention, for post-facelift cars with a second set of lambdas after the cats, the 200cell cats may occasionally trigger a post lambda oxygen reading error, and even less frequently may trigger a warning light on the dash, although it may not. There is a solution which is to weld in a couple of spark plug anti foulers in the post cat lambda mounting points and mount the rear lambdas into those. This removes them from the direct exhaust flow and will prevent the error being triggered and the CEL appearing. This is how I had it done on the previous S8, its the cheap solution. On my current S8 I had the post-cat lambda errors coded out so thy never appear. Annoyingly I couldn't remove the lambdas altogether, I think MRC (who did the coding) said there is a part of the start up routine which checks the post cat lambdas so it would't be happy if it didn't find them. Maybe if I got a whole custom remap they could get rid of them, but I stayed with the stock map for now.

Last edited by Goran; 18th June 2017 at 03:29 PM.
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  #7  
Old 18th June 2017, 05:07 PM
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Goran Goran is offline
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This is how stock cats look on a LHD S8, the RHD is almost identical.




These are the HJS cats, this is the better with both brackets easily accessed from underneath no need to remove the downpipe and front lambda.

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  #8  
Old 19th June 2017, 12:07 PM
runman99 runman99 is offline
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Quote:
Originally Posted by David's8 View Post
Whereabouts are you?
Hi David,
Am nr telford in west mids.
Regards

Mat
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  #9  
Old 19th June 2017, 12:10 PM
runman99 runman99 is offline
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Quote:
Originally Posted by ainarssems View Post
32V was in production until late 1998 so it seems like yours is a later registered early car. The cats on those earlier cars seem to be more reliable than later FL cars, the only case of failure that i remember of is with blown head gasket when coolant entered exhaust and contaminated cats. What are the symptoms that make you think they are on their way out? Not sure if there are direct fit aftermaket replacements available for these now. Most cost efective would probably be weld in universal cats.
Oh, well the symptoms are the rattle like sound similar to 'Christine' before the speedo started to go backwards ! :-)
And when it was up on ramps even cold a thump on that (RH - OS) cat produced a 'Clank' ...
Regards
Mat
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  #10  
Old 19th June 2017, 12:12 PM
runman99 runman99 is offline
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Quote:
Originally Posted by Goran View Post
If it is the cats I would go for something from Germany, like this, with metal element rather than ceramic. These are 400cell.

http://www.ebay.de/itm/Sportkat-400-...-/321751735732

You could go 200 cell if your car is pre-facelift since you dont have post-cat lambdas.
http://www.hjs-motorsport.de/produkt...talysator.html

I had two similar to these on my previous S8 always passed emissions, now I have two of these on my current S8

http://www.turbozentrum.de/0/a-31960/

There are these too also HJS a bit cheaper

https://www.turboperformance.shop/do...s-bis-2600-ccm

Hi, well I have to admit I was hoping for a significantly less costly. ?

Regards
Mat
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