A little caveat on taking in the marketing of "better detergents and additives":
The FSI engine has direct injectors, so unfortunately the fuel never ever touches the back of the valves, @S3Alex has plenty of photos of his cylinder head, I think he's done at least 2 de-cokes already. The Audi 4.0 and 4.2 V8's found in various S & RS models also suffer terribly from coking, and no amount of fuel detergent or additives will make any difference to this issue.
The 8V S3 at least has a row of indirect injectors to help alleviate this, but not on S3's sold in Canada and USA, nor the rest of the 8V petrol engine range.
I've pinched this photo from @S3Alex of his 8P S3 Engine (but all VW Audi TFSI/FSI suffer) :
(from: http://www.audi-sport.net/xf/threads/time-for-a-build-thread-big-turbo.106134/page-30#post-2241735)
The FSI engine has direct injectors, so unfortunately the fuel never ever touches the back of the valves, @S3Alex has plenty of photos of his cylinder head, I think he's done at least 2 de-cokes already. The Audi 4.0 and 4.2 V8's found in various S & RS models also suffer terribly from coking, and no amount of fuel detergent or additives will make any difference to this issue.
The 8V S3 at least has a row of indirect injectors to help alleviate this, but not on S3's sold in Canada and USA, nor the rest of the 8V petrol engine range.
I've pinched this photo from @S3Alex of his 8P S3 Engine (but all VW Audi TFSI/FSI suffer) :
(from: http://www.audi-sport.net/xf/threads/time-for-a-build-thread-big-turbo.106134/page-30#post-2241735)
