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View Full Version : Intermittent resonance/vibration between 2000-3000 rpm...only on acceleration



fed0ra
06-21-2013, 06:44 AM
So for the past couple of months I've been hearing this occasional noise that is becoming more common so I wanna get it figured out. It only comes on when I press down on the gas and it only seems to happen between 2000 and 3000 rpm. If I press down on the gas in that range sometimes I hear this (relatively) loud vibration/resonance sound coming from the front of the car; if I release the gas it goes away. It can come on immediately after pressing on the gas or it could happen while I'm accelerating, its really a crapshoot.

It almost sounds like humming or something like that, and when it goes away it almost sounds like taking a big gulp of a drink...its weird. Sometimes it sounds like a belt or something rubbing against something, but thats just a guess.

I found this thread on AudiWorld (http://forums.audiworld.com/showthread.php?t=2677673) but I can't find an example of what this sounds like. Also, mine doesn't usually come on at WOT but usually at part throttle with boost at about 0psi.

I tried to get a video of it but you couldn't really hear it.


For reference:

I drive a 2000 A4 1.8t Quattro Avant with about 107,000 miles. Only mods are cone intake, APR R1 diverter valve, TFSI coilpacks and GIAC Stage 1 (though the sound started before I chipped it).

fed0ra
06-21-2013, 06:48 AM
Also, it should be noted that I'm boosting fine and I don't have any loss of boost when the sound happens. I also don't notice any change in acceleration when the sound comes on, though I don't usually hammer it when I hear it and generally back off of the throttle to make it go away.

fed0ra
06-21-2013, 07:03 AM
Oh and timing belt was done around 75,000 miles (I think...might have been more than that). I believe the water pump was done with it.

fed0ra
06-21-2013, 03:52 PM
Nobody?

After driving around today I think I've narrowed it down a bit. The sound only seems to come on when there is positive pressure. As long as I'm in vacuum I don't hear it, but then when I hit 0psi it will come on.

fed0ra
06-21-2013, 05:30 PM
So, I may have found the issue. Apparently the R1 DV is known for "mooing" which is an apt description of what I'm hearing. I think I'm gonna pick up a forge dv and see if that changes things.

chris164935
06-21-2013, 11:29 PM
Hey, I think I am having the same or similar issue as you (and so is my best friend). The sound almost sounds like a whale or something. Lol. That's the best way I can describe it. Best guess I have been able to come up with is the DV being the culprit. http://www.audiworld.com/tech/eng6.shtml
Please, update this thread when/if you purchase a new DV to install on your car and let us know if that changes anything.

Also, where is your DV installed at? Is it on the turbo inlet pipe or the charge pipe right after the turbo?

fed0ra
06-22-2013, 05:40 AM
Interesting. Well, I ordered a Forge 007 last night and I planned on installing it in a more accessible position anyway, so hopefully I'm set. Currently it's in the stock position near the belly pan underneath the intake.

I'll update this post after I get it installed.

fed0ra
08-07-2013, 05:30 AM
I forgot that I made this thread. I installed the Forge DV but I installed it in the stock position and I no longer have the "mooing" sound from before. That's the only thing I changed so the APR DV must be the issue. I would recommend swapping your APR unit for a Forge one, assuming you are using the R1.