So this is sort of an interesting one. I have a 2004 A4 1.8t Quattro 6 speed manual, bone stock aside from a forge splitter, muffler delete, and APR Stage 1 tune.
Just to give you some insight : When i first drove home from getting the APR tune i was getting a lot of turbulence in the induction system, not so much a sound but the feeling of "buffeting" from the front underside of the car when i would boost under 4000rpm. This was because my Forge DV was dialed all the way down. I opened it up to 30 clicks and voila! smooth boost and a great DV sound.
Fast Forward...
My DV had been acting weird.. one day you'd get a great "chachachachaa" from the DV upon throttle dump, then the next day it would be a weak sounding "pshhh". i ran it routed to the n249 and it was sounding weak, and i was getting ZERO vacuum/ boost reading from the n249 line for some reason... i pulled over and looped the n249 and put the DV directly to the intake manifold and i got back full pressure and a strong sounding DV.
The next day, i removed my cone filter and returned to the stock airbox. On the drive home a still had great boost and the sound I wanted.. got home, parked, left later and the car felt sluggish and there was ABSOLUTELY ZERO sound from the DV. No pressure appeared to be being released, worried about compressor surge i downgraded to stock tune and have gone easy on the boost. But here is the kicker... I am still hitting peak boost, almost 18psi on 93 mode and almost 9psi on the stock tune. So there doesnt appear to be an actual "boost leak" and im not in limp mode... but there is no sound from the DV at all.
Now, i thought what you are thinking.. " DV is toast." I took it off and swapped it with a brand new OEM unit, and i also thoroughly tested my Forge splitter, it opens with vacuum, slams shut with boost, and kicks open when the throttle is closed, so the Forge DV is perfectly fine, and with the new OEM one same issue "NO SOUND" AND AND AND i am getting that turbulence again when i boost at anything below peak RPM's.
i cannot figure this out... the intercooler and boost hoses must be fine because i still have full boost pressure. I figured it must be a slit in the hose from the DV back into the intake because that only sees post charge release air and thus wouldnt affect boosting but would deter the release of my charge air.. but the forge splitter should be venting a good amount to atmosphere... so I imagine i would atleast hear SOMETHING..?
I don't know what it could be, i'm not familiar enough with how these induction systems are set up, so i need some help. I greatly appreciate any help you can provide, I am an AVID follower of the forum and it helps me alleviate most problems i have with my Audi's.
It's not the DV, the vacuum hose to the intake manifold, its not the n249 as it acts the same whether that is looped, or connected, its not the boost hoses going to or from the Intercooler, and it can't be the IC because there's no way i'd be hitting 18psi with a busted intercooler, or for that matter, with a major hose blown open.
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