Fluttering sound from BOV - Page 4 - Subaru Impreza GC8 & RS Forum & Community: RS25.com

VAUGHNB19 · 11-19-2006, 02:45 PM

i think i have the same problem...i noticed once I put the AFc NEO, my turbo flutters too.....at first when i start my car and drive it normally for 3 minutes it doesnt flutter, but once the car gets warmed up it starts to flutter..

VAUGHNB19 · 11-19-2006, 02:47 PM

i never thought about my car fluttering..is it bad then if my turbo flutters?

2.5~rs · 11-19-2006, 02:56 PM

waste gate?

VAUGHNB19 · 11-19-2006, 03:17 PM

what about the wastegate

FuJi K · 11-19-2006, 03:25 PM

IF the wastegate has a low spring rate, it'll flutter some too.
If you wanna know if it's WORKING or not...unplug the vacumm hose to the BOV, run it and let off the gas. IF it doesn't sound DIFFERENT then it IS the BOV you have.

All you gotta do is test, you won't know if you don't test and just assume.

VAUGHNB19 · 11-19-2006, 04:33 PM

ok i'll try it.. so is it bad then if it flutters then?

hatchbuilder · 11-20-2006, 01:45 PM

IIRC the bov should not "flutter" but perhaps I am wrong here. When you take your foot off the gas and the throttlebody snaps shut, all the air in the boost tube/TMIC or whatever, rushes back towards the turbo, this would shock the turbo and can cause damage, that is why you have a BOV to vent that charge. So when you lift, the valve opens and all that postive pressure is vented away from the turbo. So, it should not open and close repeatedly as that air would be hitting the compressor.

What I think you are hearing is the wastegate. Unlike the BOV, the WG is not an open or closed deal, it opens and closes rather rapidly and can sound like a flutter. This is true if you have an electroic boost controller at WOT as well, you can actually hear the WG open and close as the controller tries to maintain a certain boost level. If you have an external gate, it can be rather pronounced. In our lgt, we have a 5lb spring and we are just running WG boost. at just under positive pressure, when I lift, you can hear the WG cycling. It sounds like a flutter.

I don't know if a BOV will Cycle like a WG.

GM6er · 11-20-2006, 02:11 PM

I had a HKS BOV running 7.8 psi,
I had the valve spring cut short. (about 2/3). so it would release at a lower PSI.
works perfectly!.

Theres a thread about it somewhere in NASIOC

VAUGHNB19 · 11-27-2006, 05:40 PM

Quote:

Originally Posted by FuJi K

IF the wastegate has a low spring rate, it'll flutter some too.
If you wanna know if it's WORKING or not...unplug the vacumm hose to the BOV, run it and let off the gas. IF it doesn't sound DIFFERENT then it IS the BOV you have.

All you gotta do is test, you won't know if you don't test and just assume.

i did what you said, but dont you mean if it doesnt sound different or me taking it as if it does sound the same when i take it off it would be the wg? cuz it still sounded the same, fluttering when i unpluged the vacumm hose....

anyway thanx to you a good thing, when i took off the hose and put it back i was looking more around the engine, and i noticed a leaking sound near the wg and turbo....i noticed a bolt off and missind between the wg and turbo. i think and hopeing that's why my wg is fluttering and hopefully will fix all of my problems

...tomorw i plan to bring it to the shop and they will use better bolts..

VAUGHNB19 · 11-27-2006, 05:50 PM

.... im doin this because the last reply by me was not updated..thanx

11-19-2006, 02:56 PM	#33 (permalink)
2.5~rs 2.2L Car: 2005 subaru impreza RS My: Subaru Parts Join Date: May 2006 Location: minnesota Trader Rating: (0) Posts: 173	waste gate? __________________ 05 RS: Borla header, magnaflow catback, gw kit, UD pulley, tanabe springs, 20mm RSB, hankook rs2s,

11-19-2006, 03:25 PM	#35 (permalink)
FuJi K 2.5L RS-T Car: MY99 GF4 EJ225 EVO3-16G My: Subaru Parts My: Subaru Blog Join Date: Dec 2001 Location: St. Paul MN United States of America Trader Rating: (2) Posts: 4,246	IF the wastegate has a low spring rate, it'll flutter some too. If you wanna know if it's WORKING or not...unplug the vacumm hose to the BOV, run it and let off the gas. IF it doesn't sound DIFFERENT then it IS the BOV you have. All you gotta do is test, you won't know if you don't test and just assume. __________________ It's about the Top End!!!

11-19-2006, 04:33 PM	#36 (permalink)
VAUGHNB19 2.5L Car: Impreza 2.5 Rsti :) 2004 My: Subaru Parts Join Date: Nov 2006 Trader Rating: (1) Posts: 256	ok i'll try it.. so is it bad then if it flutters then? Last edited by VAUGHNB19; 11-19-2006 at 04:51 PM..

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11-19-2006, 02:45 PM	#31 (permalink)
VAUGHNB19 2.5L Car: Impreza 2.5 Rsti :) 2004 My: Subaru Parts Join Date: Nov 2006 Trader Rating: (1) Posts: 256	i think i have the same problem...i noticed once I put the AFc NEO, my turbo flutters too.....at first when i start my car and drive it normally for 3 minutes it doesnt flutter, but once the car gets warmed up it starts to flutter..

11-19-2006, 02:47 PM	#32 (permalink)
VAUGHNB19 2.5L Car: Impreza 2.5 Rsti :) 2004 My: Subaru Parts Join Date: Nov 2006 Trader Rating: (1) Posts: 256	i never thought about my car fluttering..is it bad then if my turbo flutters?

11-19-2006, 03:17 PM	#34 (permalink)
VAUGHNB19 2.5L Car: Impreza 2.5 Rsti :) 2004 My: Subaru Parts Join Date: Nov 2006 Trader Rating: (1) Posts: 256	what about the wastegate

11-20-2006, 01:45 PM	#37 (permalink)
hatchbuilder 2.7L Car: 1993 Impreza Wagon Dreadnaught Fav Mod: Turbo My: Subaru Parts Join Date: Mar 2005 Location: PDX Trader Rating: (1) Posts: 414	IIRC the bov should not "flutter" but perhaps I am wrong here. When you take your foot off the gas and the throttlebody snaps shut, all the air in the boost tube/TMIC or whatever, rushes back towards the turbo, this would shock the turbo and can cause damage, that is why you have a BOV to vent that charge. So when you lift, the valve opens and all that postive pressure is vented away from the turbo. So, it should not open and close repeatedly as that air would be hitting the compressor. What I think you are hearing is the wastegate. Unlike the BOV, the WG is not an open or closed deal, it opens and closes rather rapidly and can sound like a flutter. This is true if you have an electroic boost controller at WOT as well, you can actually hear the WG open and close as the controller tries to maintain a certain boost level. If you have an external gate, it can be rather pronounced. In our lgt, we have a 5lb spring and we are just running WG boost. at just under positive pressure, when I lift, you can hear the WG cycling. It sounds like a flutter. I don't know if a BOV will Cycle like a WG.

11-20-2006, 02:11 PM	#38 (permalink)
GM6er 1.8L Car: 2000 2.5 RS-T Aspen White Coup My: Subaru Parts Join Date: Jun 2005 Location: Vancouver BC, Canada Trader Rating: (0) Posts: 49	I had a HKS BOV running 7.8 psi, I had the valve spring cut short. (about 2/3). so it would release at a lower PSI. works perfectly!. Theres a thread about it somewhere in NASIOC

11-27-2006, 05:50 PM	#40 (permalink)
VAUGHNB19 2.5L Car: Impreza 2.5 Rsti :) 2004 My: Subaru Parts Join Date: Nov 2006 Trader Rating: (1) Posts: 256	.... im doin this because the last reply by me was not updated..thanx

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