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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N55 Turbo Engine Tuning and Exhaust Modifications - 335i Tuning > GFB DV+ Weird Sounds



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      04-14-2020, 10:39 PM   #45
ferocity02
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Quote:
Originally Posted by TheGoodTheBadTheUgly View Post
I remember you saying that you had the Injen air intake. Did you try to replace it with the stock one to see how it changes the sound?
I have not. I have no doubt the stock intake would reduce the howl sound, but I like the other sounds that the Injen intake lets pass through.

The howl to me sounds like pressurized air passing through a small hole or crack, just like when you whistle. This is indicative of a leak, IMO. Unfortunately it's super hard to pressure test the DV without some unique fixture or adapter.
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      04-14-2020, 11:43 PM   #46
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      04-15-2020, 10:48 AM   #47
TheGoodTheBadTheUgly
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Quote:
Originally Posted by ferocity02 View Post
I have not. I have no doubt the stock intake would reduce the howl sound, but I like the other sounds that the Injen intake lets pass through.

The howl to me sounds like pressurized air passing through a small hole or crack, just like when you whistle. This is indicative of a leak, IMO. Unfortunately it's super hard to pressure test the DV without some unique fixture or adapter.
If you ask me to take a guess, even if you did not, I would think that the howling noise is from the very small small amount of air that gets to be squeezed around the piston because of engineering and machining tolerances.

Because of the way the DV+ is designed, this piston is driven by pressure gradients meaning that it moves and slides in the collar of the DV+ frame, so it has to be of an extremely smaller difference of diameter than the collar to be able to move while still creating a seal.

I could see air, at the high pressures that the compressor produces, being pushed in that very tight gap between the piston and the colar. Boundary layers would be very thick and important in that small gap, thus they would induce a lot of viscous effects which you can imagine as some kind of friction. That air will manage to pass to the recirculating pipe but probably with that created friction which might be the cause of that constant howling.

If I knew how to upload a damn image I would attempt a better explanation.
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TOTALED | 2011 E90 335i xDrive - BMS Cold Air Intake - ETS Charge Pipe - ETS 7" FMIC - MHD Stage 2+ - GFB DV+ - PE Mod - VRSF Catless Downpipe - xDelete - xHP Stage 3
2015 E84 X1 35i M-Sport
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      12-17-2021, 10:25 PM   #48
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Anyone have a fix for the low throttle whistle? Here's some more info. I installed my PS2 with the TS dual port. After a few logs during tuning I realized I might have messed up the wastegate actuator when I installed it. Sure enough it was around 9". I readjusted to a little over 6 as recommended by Pure. That's when I started getting a whistle/howl both at cold start (for 5 seconds) and at light throttle between 1500-2500rpm. I turned on 'cold start noise reduction' in MHD and the cold start whistle was gone. But I still have the cruising whistle. Note that it only whistles in lower gears mostly. Not at highway speed. I also have a Pure inlet.

So adjusting my wastegate properly is when it started. Also I did reinstall the stock DV and The noise is still there. So I'd rule out the DV. I'm leaning to some weird resonance in the turbo inlet. What inlets are you guys running?

My car is running great in every other way so this is getting on my nerves. Really hope someone has found a fix for this. I'm thinking of trying a silicone inlet to test because I feel the thin aluminum inlet is causing the harmonic. No idea what else it could be. At first I thought u had a dying turbo and was really bummed but was "glad" to hear it's not a totally uncommon situation.
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      05-26-2023, 06:47 AM   #49
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Quote:
Originally Posted by bandook View Post
Anyone have a fix for the low throttle whistle? Here's some more info. I installed my PS2 with the TS dual port. After a few logs during tuning I realized I might have messed up the wastegate actuator when I installed it. Sure enough it was around 9". I readjusted to a little over 6 as recommended by Pure. That's when I started getting a whistle/howl both at cold start (for 5 seconds) and at light throttle between 1500-2500rpm. I turned on 'cold start noise reduction' in MHD and the cold start whistle was gone. But I still have the cruising whistle. Note that it only whistles in lower gears mostly. Not at highway speed. I also have a Pure inlet.

So adjusting my wastegate properly is when it started. Also I did reinstall the stock DV and The noise is still there. So I'd rule out the DV. I'm leaning to some weird resonance in the turbo inlet. What inlets are you guys running?

My car is running great in every other way so this is getting on my nerves. Really hope someone has found a fix for this. I'm thinking of trying a silicone inlet to test because I feel the thin aluminum inlet is causing the harmonic. No idea what else it could be. At first I thought u had a dying turbo and was really bummed but was "glad" to hear it's not a totally uncommon situation.
G'day mate

Did you ever get rid of the whistle noise? And did you find lowering the wg setting gave you quicker boost/spool?

Thanks Mark
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      06-07-2023, 06:43 PM   #50
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Quote:
Originally Posted by mwpa71 View Post
G'day mate

Did you ever get rid of the whistle noise? And did you find lowering the wg setting gave you quicker boost/spool?

Thanks Mark
The noise is still there. It's most likely because of the inlet, I've heard others confirm this. Setting the wg correctly doesn't really affect spool speed, but it does allow it to hold boost. I ran out of wg duty cycle before I could hit target, setting it right fixed that.
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      06-17-2023, 12:10 AM   #51
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Quote:
Originally Posted by bandook View Post
The noise is still there. It's most likely because of the inlet, I've heard others confirm this. Setting the wg correctly doesn't really affect spool speed, but it does allow it to hold boost. I ran out of wg duty cycle before I could hit target, setting it right fixed that.
Hmmm.. not so sure.. I had ps2 gfb no strange noise s ever , bms intake. On car for 4 years. Recently changed to 750...now I have that low boost weird whistle...I finished all my boost testing now I will switch over to turbosmart.. (I swapped to turbosmart when 750 went in..it had no strange noises but I couldn't boost test with it..the noise came after reinstalling gfb...not sure what's happening but in maybe related to the the oem dv part. Will let you know.
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      12-13-2023, 10:32 PM   #52
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Do you guy mean this sound? LOL Running hybrid turbo and TS bov now. I think it's related to the aluminum inlet came with the turbo. My original MST+TS+stock turbo didn't have this sound. Car pulls strong and no boost leak according to my tuner, wastegate duty% very healthy. Just the "owl hooting" sound kinda embarrassing when I drive by my son's school. Like someone is blowing clarinet in the engine bay LOL. Over 3k rpm, the sound will disappear.
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