I've had this happening as long as I can remember (can't swear it happened when totally stock, but definitely since being chipped). I've been through the progression of stock DV, 710N, and recently APR R1, and also from APR stage 1 to stage 1+ during this time and yet this has consistently been happening. It's hard to describe this sound since it's subtle, but here it is: when accelerating, primarily in lower RPM range (2000 to 3000) I get a kind of shuddering or harmnonic resonance. It's low volume, low frequency, and cycles on/off several times a second. It doesn't seem to happen at higher revs. Anyone experience this, and know what it would be?

Some theories I've had (pure speculation) are DV fluttering (although as described above it's happened with 3 different DVs), or intake air flow. I remain baffled...

Thanks

 

Happened to me. I dunno wtf it could be. First I also thought it was my DV but I've swapped them and it still does that. Next I'm going with Forge. But I think I need to check my lines and my SAP. I think there might be an air leak somewhere than makes this sound. I get it at low rpms or when I'm crusing, never when I gun it. It also seems to come in random but primerily under light acceleration.

 

Probably not be the same issue then - I get the noise only on hard acceleration...

 

Have you had your Fuel Pumps checked? (I believe there are two if you have Quattro) I have to have one of mine replaced after it made some strange noises at start up and under acceleration.