Turbo Flutter

The_E92_Fan · 05-24-2017, 05:18 PM

After i accelerate, if i slightly let off the throttle, i hear air coming out of the passenger side of the engine bay, both in flutters and just air being let out. I don't believe i have a boost leak, and it started happening after i installed synapse BOV. Has anyone had this issue? Is it actual turbo flutter?

BeastMode335i · 05-25-2017, 08:19 AM

Quote:

Originally Posted by The_E90_Fan

After i accelerate, if i slightly let off the throttle, i hear air coming out of the passenger side of the engine bay, both in flutters and just air being let out. I don't believe i have a boost leak, and it started happening after i installed synapse BOV. Has anyone had this issue? Is it actual turbo flutter?

Sure it's not the BOV you're hearing?

Antetokounmpo · 05-25-2017, 08:21 AM

So you hear air when you let off the throttle after you installed a BOV... got it.

Underground6t9 · 05-25-2017, 08:25 AM

^hahaha

BeastMode335i · 05-25-2017, 08:28 AM

Quote:

Originally Posted by Harambe

So you hear air when you let off the throttle after you installed a BOV... got it.

I thought it was a troll post at first, but then again I remembered who's buying these cars now and I didn't put it past the OP lol..

sirdaft1 · 05-25-2017, 08:41 AM

Woosh sound = normal/good.
Flutter sound = compressor surge/not good.

http://www.turbosmartusa.com/technic...pressor-surge/

The_E92_Fan · 05-25-2017, 08:58 AM

Ill have to post a vid when I've got time. The only trouble is the car is straight piped and it may be hard to hear it. This is happening ONLY when i slightly let off the throttle, from say, 60% or higher. My inlets are relocated by the way. Im fairly certain i do not have a boost leak, allowing the air to escape anywhere. Basically what is happening is the BOV is not opening if i only slightly let off the throttle, so the air is coming right back out the turbos. Under these conditions, there is NO BOV release. Is there a lighter spring for the synapse? Should i just replace the BOV?

The_E92_Fan · 05-25-2017, 08:21 PM

Update: took the spring out and i still had turbo flutter under the same conditions. About half the time, it would dump much faster, but i still would get air coming out of the turbos. At least once, the BOV didn't open and had complete flutter dump. This is very frustrating. Time to switch BOV?

Donutz · 05-26-2017, 06:42 AM

Before spending any more money, personally, I would put the stock charge pipe and diverter valves back in and retest. You want to be sure it isn't compressor surge.

The_E92_Fan · 05-26-2017, 02:33 PM

Switched back to stock charge pipe. I still get some turbo flutter. I took off hot side intercooler piping and see some oil spray, but i don't believe that this is a simple boost leak. Will update next week with a video link. My car is so loud, you can't hear anything else, so my new exhaust will help.

The_E92_Fan · 09-27-2022, 08:31 PM

many years later i return to mention that the synapse BOV i had worked perfectly but in very specific cases where i only come half off the throttle i could get the charge air to shoot back out the turbo, getting flutter. probably due to the BOV spring being just a pound or two too stiff and/or the throttle not fully closing (since i was only half off-throttle) and therefore not pulling vacuum in the manifold. it was harmless.

05-24-2017, 05:18 PM	#1
The_E92_Fan V8 Bait 206 Rep 769 Posts Drives: your mom Join Date: Jun 2016 Location: your moms house iTrader: (0)	Turbo Flutter After i accelerate, if i slightly let off the throttle, i hear air coming out of the passenger side of the engine bay, both in flutters and just air being let out. I don't believe i have a boost leak, and it started happening after i installed synapse BOV. Has anyone had this issue? Is it actual turbo flutter?
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05-25-2017, 08:21 AM	#3
Antetokounmpo Brigadier General 1552 Rep 3,475 Posts Drives: E90 6MT FBO; '18 F150 Platinum Join Date: Jul 2013 Location: WI iTrader: (3) Garage List 2018 Ford F-150 Pla ... [0.00] 2008 BMW 335xi [0.00]	So you hear air when you let off the throttle after you installed a BOV... got it. __________________ 2008 335xi 6MT \| VRSF Catless DP \| VRSF 7" FMIC \| VRSF CP \| TIAL BOV \| DCI \| MHD 2+ BC Racing BR \| Stoptech 600 \| Firehawk Indy 500 255 Square \| Atric Altimax 225 Sq. 2018 F-150 Platinum 701A \| FX4 \| 3.5 EcoBeast
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05-25-2017, 08:25 AM	#4
Underground6t9 Lieutenant Colonel 317 Rep 1,735 Posts Drives: BMW 335xi, Lexus is250 Join Date: Jan 2014 Location: Eugene, OR iTrader: (2)	^hahaha
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05-25-2017, 08:41 AM	#6
sirdaft1 Brigadier General 2203 Rep 3,336 Posts Drives: X5 & E90 WTCC Widebody Racecar Join Date: Feb 2013 Location: Chicago West Burbs iTrader: (9) Garage List 2007 E90 WTCC Wideb ... [9.50] 2012 BMW X5 xDrive35i [9.00]	Woosh sound = normal/good. Flutter sound = compressor surge/not good. http://www.turbosmartusa.com/technic...pressor-surge/
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05-25-2017, 08:58 AM	#7
The_E92_Fan V8 Bait 206 Rep 769 Posts Drives: your mom Join Date: Jun 2016 Location: your moms house iTrader: (0)	Ill have to post a vid when I've got time. The only trouble is the car is straight piped and it may be hard to hear it. This is happening ONLY when i slightly let off the throttle, from say, 60% or higher. My inlets are relocated by the way. Im fairly certain i do not have a boost leak, allowing the air to escape anywhere. Basically what is happening is the BOV is not opening if i only slightly let off the throttle, so the air is coming right back out the turbos. Under these conditions, there is NO BOV release. Is there a lighter spring for the synapse? Should i just replace the BOV?
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05-25-2017, 08:21 PM	#8
The_E92_Fan V8 Bait 206 Rep 769 Posts Drives: your mom Join Date: Jun 2016 Location: your moms house iTrader: (0)	Update: took the spring out and i still had turbo flutter under the same conditions. About half the time, it would dump much faster, but i still would get air coming out of the turbos. At least once, the BOV didn't open and had complete flutter dump. This is very frustrating. Time to switch BOV?
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05-26-2017, 06:42 AM	#9
Donutz Lieutenant 140 Rep 476 Posts Drives: 335i Join Date: Sep 2015 Location: Toronto, eh iTrader: (2)	Before spending any more money, personally, I would put the stock charge pipe and diverter valves back in and retest. You want to be sure it isn't compressor surge.
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05-26-2017, 02:33 PM	#10
The_E92_Fan V8 Bait 206 Rep 769 Posts Drives: your mom Join Date: Jun 2016 Location: your moms house iTrader: (0)	Switched back to stock charge pipe. I still get some turbo flutter. I took off hot side intercooler piping and see some oil spray, but i don't believe that this is a simple boost leak. Will update next week with a video link. My car is so loud, you can't hear anything else, so my new exhaust will help.
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09-27-2022, 08:31 PM	#11
The_E92_Fan V8 Bait 206 Rep 769 Posts Drives: your mom Join Date: Jun 2016 Location: your moms house iTrader: (0)	many years later i return to mention that the synapse BOV i had worked perfectly but in very specific cases where i only come half off the throttle i could get the charge air to shoot back out the turbo, getting flutter. probably due to the BOV spring being just a pound or two too stiff and/or the throttle not fully closing (since i was only half off-throttle) and therefore not pulling vacuum in the manifold. it was harmless. __________________ Broke AF
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