Since my bottom end rebuild I havent given my car any grief with the boost wicked up but today I flicked the switch and gave it some beans. Through the gears it seemed to be going as I would expect but then into 6th and it felt flat. I then noticed that it sounds different, with the wastegate/DV? making a really cool fluttery noise in between changes. It has never sounded like this before! On idle I can also hear through the airfilter what sounds like back pressure, or pressure coming back out of the filter? I have swapped the DV but to no avail so assume the turbo or wastegate/actuator. Any ideas as where to go next please? Thanks BTW - mk2 Golf with 225 TT engine and MBE ECU.
Connection to DV is not good? It will open at higher boost, as it will not have the pressure to keep it closed (helped by the spring). If there is no vaccum to open it up when throttle is released, it will do the sound you are describing. Check for a loose vaccum hose, or a hole in it.
