Need some help please. I have a 2007 A3 2.0 TDI 170, which has covered 78,000 miles. The car has just developed a hissing / air escaping noise in 3rd, 4th and 5th gear when accelerating. The noise occurs between 1500rpm and 2000rpm only. I believe it's when the turbo initially spools up under load. I took the car to Audi who advised that the intake manifold was the cause and needed replacing, which they did. I picked the car up and the same noise can still be heard, so it went back. Just had a call from the tech who advised they have pressurised the system, and cannot find any leaks. (NB - the noise is not the usual 'whine' you get from the turbo, more like the sound you get from a punctured tyre when the pressurised air is escaping) Any advice would be appreciated as I suspect Audi will return the car with it still exhibiting the same symptoms.