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Discussion Starter #1
Hi to Everyone!
Glad to be a member.
This is a good one.

I recently encountered a guy who was not happy with the performance of his A6/18T. So he removed the exhaust catalitic converter and installed a straight section at that point. Now the engine has a rattle. No loose retainer bolts or anything. It sounds like a bit of mettal oddly rolling around in a chamber of sorts. The car went to the Audi dealer (to the head mechanic) and no one had a clue as to what's causing the rattle. Remember...just the converter was removed. He initially tried to sell me this car, but the rattle could not be explained. The chief mechanic says "other than that...the car works fine". I'm sorry. But this is an AUDI A6 18T and that is just not acceptable. Just think of the emotional stress of having to make excuses for that annoyance. There could be long term damage.


ps.
VW/AUDI?
Passat & Audi A4 or 6 18T...Is it just a body swap?
 

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PS
the audi a4 and passats are the same but the A6 arent
 

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Discussion Starter #3
Do you have any insight into the rattle problem? does that engine depend on being set up with the correct exhaust? removing the cat does work with some cars to increase power but not with
all, it could be valve rattle I'm told (what valve?) we could try replacing the cat to see if the
problem disappears, or to compensate the removal of the cat, an ecu re
programming may be required to set the ignition curve which may now be
different with reduced exhaust back pressure.
 

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I'm leaning toward knock and ping from the engine valve train. Audi uses some pretty complex computer programming and sensors to detect this. These are written for the exhaust with the cat. You can try some higher octane fule and see if this helps.
 
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