I have had my Mk5 GTI 2005 for few months now.
I love the car to bits.. BUT when the car warms up it sounds like a derv lol
From cold it sounds perfect but slowly as it gets warm the worse it sounds, only on tick over. I have read that they suffer with noisey injectors but also read it can be the chain tensioner.
I have a 55 plate GTI with an AXX engine, and mine is noisy at idle too. From reading around all the FSI/TFSI forums, the consensus seems to be, if it definitely sounds like a diesel from inside the cabin, then you should have it fixed. You don't hear the sound any more after 1200-1500 rpm as the load then takes the slack out of the cam chain.
The solution is to have the cam chain and tensioner replaced, and if you're unlucky the adjuster, which adds £280 to the bill - the cam chain, tensioner and gaskets run to just £100-120, but there is a few hours of labour involved, and a special toolkit is needed to do the work.
I'm sure a lot (most?) people have a diesel sounding tickover to some extent, but I'd be interested to know how many people's idle sounds like this on the inside?
http://www.youtube.com/watch?v=4AZ0s1imkVU&feature=youtu.beMine isn't this bad yet, but I'm making enquiries about the costs to have it fixed, as it certainly won't get any better. A local independent said all FSI engines are noisy and it was perfectly normal, and a local VW dealership agreed there is an additional noise, but they don't know what it might be... which wasn't exactly encouraging.
Rich.