Loosing Boost, flutter sound
 

Hey guys im new to the audi scene, and im in need of some help. Recently i bought a 2004 audi a4 1.8t. It had the K04 installed and a front mount intercooler, bigger injectors the whole shibang. The guy i bought it from only owned it for 3 months and he dosent know if it was tuned or not. But anyways when i was heading home it ran perfect could feel and hear the turbo spooling and all, it was as clean as a whistle. After about 2-3 weeks after owning it, i noticed a lose in boost, it will go in and out. I can roll the window down and still hear it but it will spool then start fluttering. So i got kind of curious and popped the hood i couldnt help it but heard this loud whistle sound. Sounded like a vaccum leak but wasnt throwing up any codes. only place i could hear it coming from is the breather hose that goes from the suction jet pump to the intake manifold, I replaced it, but still the whistle (hissing) sound was there.

Any Advice would be much appreciated!

Thanks.

I suggest a boost leak test. This will help you determine whether or not you actually have an air leak, or if it's something else like bad diverter valve.

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BTW your vacuum lines may look a little different than in that DIY, because Audi made several revisions to the B6 vacuum lines & emissions systems throughout the years.

So ive been fiddling around with some hoses and noticed that one hose didnt even have a clamp on it, so i clamped it, and i look around where that hose was and noticed something off with one of the angled hoses. I think I found what that sound was coming from at the end of the hose it looks like slices. ill replace it and see what happens if that doesnt do anything ill do a leak test.