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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 16th May 2011, 11:57 AM
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The_Laird The_Laird is offline
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Default Not the Cat curse again - surely?

The list gets longer!

2 cats on my old A8, 2 new 'sports' cats on my S8, a new cat on my daughter's 206 just after we picked it up and, after standing close to briang9's S8 at the Scotland mini-meet, his cat went too!

Then my engine management light came on again, so I swung by A4 Audi on the way home last week and the VagCom said both cats were out of tolerance. But the light went off the following day and has stayed off for a couple of hundred miles or so.

The new cats are only around 7 months old and under guarantee, but is it likely to be them or maybe just a bit of gubbins in the petrol (BP Ultimate, always)?

Any thoughts guys?

BTW - I'll stand well away from your '8 at June's meet for a small fee!
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Old 16th May 2011, 10:20 PM
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Which lambdas where showing the fault. If it's the one after the CATS then it will probably be because you have sports cats.
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Currently,
2000 S8, Merlin Purple, Leather Pack 1, Winter Pack 1, SPAX adjustable suspension, AP Racing 6 pot front caliper, 385mm fully floating disks, EBC Yellow Stuff Pads, Black Diamond grooved rear disks and predetor pads, D2 Doctors Brake Block.
1997 4.2 A8SQ - the Projekt. 12 years and ongoing!
1997 4.2 A8SQ - Ming Blue. Restoration sat waiting; saved from the Scrapyard
2003 C5 Allroad 4.2Q - Cobolt Blue. Towing car. Laid up awaiting manual conversion.
2005 C5 Allroad 2.5TDi FE - Grey - Workhorse.
2015 Q3QS SLine - Daytona Grey. Lots of extras! Long Haired Admirals cutter.

Previously
2003 C5 A6 1.9TDI FWD - Loaner from D2 Doctor Lifex
1997 S8 - Ming Blue. Loaned out and written off. I loved that car. My first engine swap after cambelt failure.
1996 4.2 A8SQ - Ming Blue. 178k on a cambelt! Trader's 8. Delivered to A8Parts at Lifex.
2003 2.8 A8SQ - powder blueish. Fill in for a while. Sold on.
1998 1.8T A4 Avant FWD. Ming Blue (there's a theme here), PEX for the 97 S8.
And a list of non VAG going back 40 years before I saw the light.
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Old 17th May 2011, 05:14 AM
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Not sure. I'll call Andy and see. Why would the sports cats make the warning light come on and then go off again?
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Old 17th May 2011, 06:03 AM
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You have a FL S8 Jim, with Lambdas before and after the cats. The ones after the cats monitor the efficiency of the cats. With the sports cats there are generally only 100 or 200 CPI whereas in the standard cat there is 400 CPI. The more CPI the better the cats clean up the exhaust gasses. The less CPIs the better the car performance. The post cat Lambdas are probably registering the exhaust gasses out of programmed range occasionally and throwing a fault. There is a modification that can be made to the lambda housing that eradicates this problem.

Here is a thread on the subject.

This thread discusses the technique to alter AFR; but it is the same for post cat lambdas to stop faults.
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Conan (the Librarian)

Watch it if you dare

Currently,
2000 S8, Merlin Purple, Leather Pack 1, Winter Pack 1, SPAX adjustable suspension, AP Racing 6 pot front caliper, 385mm fully floating disks, EBC Yellow Stuff Pads, Black Diamond grooved rear disks and predetor pads, D2 Doctors Brake Block.
1997 4.2 A8SQ - the Projekt. 12 years and ongoing!
1997 4.2 A8SQ - Ming Blue. Restoration sat waiting; saved from the Scrapyard
2003 C5 Allroad 4.2Q - Cobolt Blue. Towing car. Laid up awaiting manual conversion.
2005 C5 Allroad 2.5TDi FE - Grey - Workhorse.
2015 Q3QS SLine - Daytona Grey. Lots of extras! Long Haired Admirals cutter.

Previously
2003 C5 A6 1.9TDI FWD - Loaner from D2 Doctor Lifex
1997 S8 - Ming Blue. Loaned out and written off. I loved that car. My first engine swap after cambelt failure.
1996 4.2 A8SQ - Ming Blue. 178k on a cambelt! Trader's 8. Delivered to A8Parts at Lifex.
2003 2.8 A8SQ - powder blueish. Fill in for a while. Sold on.
1998 1.8T A4 Avant FWD. Ming Blue (there's a theme here), PEX for the 97 S8.
And a list of non VAG going back 40 years before I saw the light.
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Old 17th May 2011, 07:18 AM
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Thanks again oh font of all knowledge!

Might pop back to the guys who fitted the cats and ask them to do this
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Old 17th May 2011, 10:13 AM
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na na na na CAT MAAAAANNNNNN!!!
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