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Old 04-28-2010, 01:42 PM   #1
dur4ce
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Default Help with BPV flutter after fmic install

So last weekend I installed a TurboXS catted downpipe, cai, and fmic on my heretofore stock 2009 WRX engine. Things went well and after a problem with the throttle body inlet popping off under boost everything seemed fine.

Everything except the fact that my bpv does not vent with a single "psh!" sound like other bpv's on an fmic. Instead, when I let off the throttle after building some boost I get a fluttering sound. I think the problem is that my bpv isn't actually venting and instead I'm getting compressor stall/surge. It sounds just like the videos of off boost compressor stall that can be heard on youtube, ect.

Here are some more pieces of relevant info:
1. I have a maddad boost gauge running off a T that is in the bpv vacuum line, about 5" from the valve
2. I've got a wideband o2 sensor and my afr's are running pretty normally, at about 14.2 at idle and cruising.
3. I have NOT leak tested the fmic yet, but I'm fairly confident that there isn't a major leak (all joints secured with t-bolts)
4. I have NOT yet replaced the throttle body inlet with the AVO silicone tb inlet I ordered. Should be delivered tonight.
5. Since the fmic, cai and dp were all installed at once, I can't tell if the flutter was present before the fmic install

My best guess is either the t in the vacuum line isn't a large enough inner diameter to let the BPV see the necessary vacuum to open, or for some reason my bpv is just buggered.

I think the best approach will be to install the tb inlet to make sure I'm not leaving at the tb (unlikely the problem) and fine a straight through hose coupler with a larger inner diameter and replace the T with that to see if the BPV vacuum line is the culprit. After that I don't know what to do except buy a aftermarket BPV (or recirc bov) to replace the stock one. But the stock one should be just fine... Ugh!

I would appreciate any advice that you could give. I just would like to get this taken care of before I really try out the full capabilities of my stage 2 setup.

Thanks!

-Steve
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Old 04-28-2010, 02:17 PM   #2
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1. i have the TXS FMIC and the T-bolts suck!! replace them all! did a check and there was nothing i could do on 7 of them, they all leaked bad. had to get the regular worm clamps and they were all fixed.

2. as for the compression surge that is what your hearing and its normal. just have to live with it. if it was bad CS would know it!! a little is fine.

3. take off the rubber piece that goes around the stock throttle body coupling!! trust me, i couldnt do more than 1 pull on the dyno or street without taking it off and re-tightening it. it will blow off every time.
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Old 04-28-2010, 03:20 PM   #3
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Thanks for the input. I blew the tb coupling the first night, then took off the rubber thingy and retightened it. It will be replaced by the avo tb coupling tonight, however. That should be better.

So you did a pressure test of the piping and they all leaked? That's odd, but I'll definitely check it out.

You couldn't by any chance post a video of your cs could you? It would be nice to know the sound I hear matches up with the one you've got. It would be a great help for me.

Thanks again!

-Steve
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Old 04-28-2010, 04:22 PM   #4
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Quote:
Originally Posted by dur4ce View Post
Thanks for the input. I blew the tb coupling the first night, then took off the rubber thingy and retightened it. It will be replaced by the avo tb coupling tonight, however. That should be better.

So you did a pressure test of the piping and they all leaked? That's odd, but I'll definitely check it out.

You couldn't by any chance post a video of your cs could you? It would be nice to know the sound I hear matches up with the one you've got. It would be a great help for me.

Thanks again!

-Steve
OMG $70 for that coupling!! jesus what a rip off, you can get couplings on ebay for $10 in any size but this shape will be impossible to find! dammit

ya, pressure test showed almost all leaked, i think a few were fine and 1 or 2 were fixed but 7 could not be so we replaced with worm clamps and it fixed them all right up. we hate T-bolt clamps!

sorry no video, it just sounds like the turbo is fluttering whenever you let off the gas, in boost or out of boost! you can hear it right out of the filter on your intake. its just a small flutter, you cant hear it in high boost when the BOV is really working and doing its job.

Last edited by synolimit; 04-28-2010 at 04:31 PM.
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Old 04-28-2010, 04:37 PM   #5
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The noise you are hearing is more prevalent in a FMIC installation. It could be normal. My friend's car made more noise when going from TMIC to FMIC.

What kind of BPV are you using? The factory one?

My other friend's evo made this noise too. I think it's just due to the piping and sound waves reacting with the piping vs the TMIC end tank.

Last edited by jay25RS; 04-28-2010 at 04:43 PM.
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Old 04-28-2010, 04:46 PM   #6
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are you running stock bpv? when i installed my fmic on my ej20g i had the same problem and figured out that it was because the intercooler and piping had a much higher volume than stock tmic. the stock bpv couldent flow enough air to keep it from surging. solution is to get a bigger bpv like a turbosmart or get a good vent to atmosphere valve (like a tial).


John
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Old 04-28-2010, 05:05 PM   #7
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What you are probably hearing is Wastegate flutter. My understanding is that the wastegate is rapidly fluttering to control boost (opening\closing so to speak so it doesn't surge). Mine does this lightly. When letting off from WOT. Its normal and not an issue according to tuner and Forced Performance. Compressor surge you hear even when accelerating and this is bad. I spoke to Forced Performance on this and that is what they explained so I am just reposting it here.

I had the throttle body popping off as well. Just take off the stupid rubber things and put it back on there with some hairspray and your clamps and save the $$$. I hit 24 psi with no issues. I used a T Clamp. Boost leak tested with no issues. Boy did it scare the crap out of me when it first happened! I replaced my stock BPV with Forge Recirc and it did not stop the fluttering. Tried with different springs etc.

Last edited by TheBrandon; 04-28-2010 at 05:11 PM.
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Old 04-28-2010, 06:22 PM   #8
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Thanks for all the input.

Yes, I am on the stock BPV. The thing is, I regularly ride in an 08 that is stage 2 with a fmic and I don't hear any flutter. I think I'm going to put the throttle inlet on and just spend some time playing around with it seeing if anything helps. I'm not going to shell out $texas for a new bpv unless I really get a good indication that it is needed.

And yea, TheBrandon, when the tb hose popped off on me and then the car died it scared the crap out of me. I didn't actually find the problem until the next day, and I spent the night wondering if I had totally effed my engine. Glad it was resolved so easily!
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Old 04-29-2010, 11:10 AM   #9
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Quote:
Originally Posted by dur4ce View Post
Thanks for all the input.

Yes, I am on the stock BPV. The thing is, I regularly ride in an 08 that is stage 2 with a fmic and I don't hear any flutter. I think I'm going to put the throttle inlet on and just spend some time playing around with it seeing if anything helps. I'm not going to shell out $texas for a new bpv unless I really get a good indication that it is needed.

And yea, TheBrandon, when the tb hose popped off on me and then the car died it scared the crap out of me. I didn't actually find the problem until the next day, and I spent the night wondering if I had totally effed my engine. Glad it was resolved so easily!

My 08 did not have fluttering either with the FMIC and stock turbo. I have 0 idea if this is accurate so take it as for sure not certain. I have heard that a turbo that is being run in more of its efficiency range is less likely to have the flutter. You're friend with an 08 is probably boosting 16-18 psi which is the wall for this turbo and it falls flat on its face with the wastegate not having to work to make sure there are no spikes. I have slight fluttering with the 68HTA at 19-20psi but this turbo comes alive around 21-23 I have heard. Can you post a sound clip? I am going to go with what you are experiencing is totally normal if in fact it is simply a wastegate flutter. On the TurboXS FMIC are you sure you added the rubber gasket back into the BPV? Also, the hose plugging into the back of the manifold is secured?
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Old 04-29-2010, 11:51 AM   #10
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I also have fluttering on my 06. I just installed a fmic, intake and turbo inlet hose.
Also when driving normal when i let off the throttle i get a little hesitation normally under vacuum but also under boost if i dont shift.

From what I hear from friends is that the stock re-circ valve shouldnt flutter.

mine fluttering coupled with the hesitation when letting off the throttle makes me think something is wrong.
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Old 04-29-2010, 03:07 PM   #11
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Quote:
Originally Posted by dur4ce View Post
So last weekend I installed a TurboXS catted downpipe, cai, and fmic on my heretofore stock 2009 WRX engine. Things went well and after a problem with the throttle body inlet popping off under boost everything seemed fine.

Everything except the fact that my bpv does not vent with a single "psh!" sound like other bpv's on an fmic. Instead, when I let off the throttle after building some boost I get a fluttering sound. I think the problem is that my bpv isn't actually venting and instead I'm getting compressor stall/surge. It sounds just like the videos of off boost compressor stall that can be heard on youtube, ect.

Here are some more pieces of relevant info:
1. I have a maddad boost gauge running off a T that is in the bpv vacuum line, about 5" from the valve
2. I've got a wideband o2 sensor and my afr's are running pretty normally, at about 14.2 at idle and cruising.
3. I have NOT leak tested the fmic yet, but I'm fairly confident that there isn't a major leak (all joints secured with t-bolts)
4. I have NOT yet replaced the throttle body inlet with the AVO silicone tb inlet I ordered. Should be delivered tonight.
5. Since the fmic, cai and dp were all installed at once, I can't tell if the flutter was present before the fmic install

My best guess is either the t in the vacuum line isn't a large enough inner diameter to let the BPV see the necessary vacuum to open, or for some reason my bpv is just buggered.

I think the best approach will be to install the tb inlet to make sure I'm not leaving at the tb (unlikely the problem) and fine a straight through hose coupler with a larger inner diameter and replace the T with that to see if the BPV vacuum line is the culprit. After that I don't know what to do except buy a aftermarket BPV (or recirc bov) to replace the stock one. But the stock one should be just fine... Ugh!

I would appreciate any advice that you could give. I just would like to get this taken care of before I really try out the full capabilities of my stage 2 setup.

Thanks!

-Steve
When you're listening for the "whoosh!" are you boosting? If you are and your having issues with the throttle body hose popping off then I ask, "How many washers are you using in your TXS BPV?" Too many washers and you're asking for trouble! I'm running with 0 washers, without issue.

Like others have said, it could be the wastegate you are hearing.... When I went to my Invidia DP, you could suddenly hear the wastegate fluttering like a flag in a hurricane! Could just be the sounds the Subies are known for and you may not have any issues..........

But if you have too many washers in the BPV, the vacuum created in the IM may not overcome the spring tension, the piston doesn't move.... and pop goes the TB inet hose! Plus you're going to be reducing the longevity of your turbo because of the back pressure your putting it under everytime you're boosting, let off the throttle, and the BPV doesn't open. You will kill the journal bearings in your turbo! Its just all around bad to put too much pre-load on the BPV spring.

I took all my washers out because I could never find out how many was too many and how many were too few.... But my car has no issues hold boost under WOT if thats what anyone is asking.
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Old 04-29-2010, 03:58 PM   #12
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Originally Posted by synolimit View Post
ya, pressure test showed almost all leaked, i think a few were fine and 1 or 2 were fixed but 7 could not be so we replaced with worm clamps and it fixed them all right up. we hate T-bolt clamps!
Just worm clamps? "You're braver than I thought!" (name that movie) Not to thread-jack, but I used the t-bolts (from TXS) and spaced them apart enough to use worms as well.... and yes I heat wrapped my pipes too, but the glue wasn't doing its job very well so I used worm clamps.... Ghetto? Maybe, but effective.

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Old 04-29-2010, 04:24 PM   #13
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they still give an ass load of clamp force, plus with the ribs on all the pipes, they cant blow off. they'll be more than fine.
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Old 04-29-2010, 04:31 PM   #14
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@scramjett As I said earlier, I'm using the stock bpv, not the txs one. I don't *think* the stock bpv is adjustable at all.
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Old 04-30-2010, 12:04 AM   #15
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Quote:
Originally Posted by dur4ce View Post
@scramjett As I said earlier, I'm using the stock bpv, not the txs one. I don't *think* the stock bpv is adjustable at all.
is your bpv crushed? if it is there is too much spring tension for it to open under lighter loads causing the fluttering sound. i have a stock bpv that is crushed and, the same thing occurs with mine. i only get the "psh" sound after boosting a decent amount. you're correct about it not being adjustable, the only thing to do really is swap it out if the bpv is the issue.
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Old 04-30-2010, 08:33 AM   #16
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Quote:
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is your bpv crushed?
Being that he has a 2009 WRX, and the Stock BPV, he can't have it crushed. It is a plastic valve.
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Old 04-30-2010, 01:20 PM   #17
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Being that he has a 2009 WRX, and the Stock BPV, he can't have it crushed. It is a plastic valve.
gotcha, i didnt know. thanks man
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Old 05-11-2010, 09:25 PM   #18
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So I made a couple videos with the sound I'm getting. Sorry for the video component, but the sound is what is important anyway.



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Old 06-03-2010, 02:07 PM   #19
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I have the same issue with my 09 WRX. Cobb Access port, Perrin FMIC, Perring Stage 3 Map, Perrin CAI, Invidia Catless Divorse Downpipe and Invidia full exhaust. Was there ever a fix for this fluttering issue or "it is what it is" .??
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Old 06-03-2010, 04:49 PM   #20
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Quote:
Originally Posted by dur4ce View Post
So I made a couple videos with the sound I'm getting. Sorry for the video component, but the sound is what is important anyway.

2009 WRX Stg2 bpv flutter 1

2009 WRX Stg2 bpv flutter 2

2009 WRX Stg2 bpv flutter 3
that sounds normal. the stock BPV isnt going to have a one time open "woosh". i dont hear compressor surge so your not getting the same sounds i am.
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Old 06-03-2010, 04:52 PM   #21
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Quote:
Originally Posted by badpmpn0y View Post
I have the same issue with my 09 WRX. Cobb Access port, Perrin FMIC, Perring Stage 3 Map, Perrin CAI, Invidia Catless Divorse Downpipe and Invidia full exhaust. Was there ever a fix for this fluttering issue or "it is what it is" .??
if yours sounds like the video its normal BPV release. should sound like that even with your TMIC back on. if yours sounds different like mine its probably compressor surge from all the bends in the FMIC pipe putting back pressure on the turbo and causing a little flutter. its normal for both though. your gonna have a little surge unless you make your piping as strait as possible which no one wants to do.
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Old 10-15-2012, 03:29 AM   #22
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Quote:
Originally Posted by synolimit

if yours sounds like the video its normal BPV release. should sound like that even with your TMIC back on. if yours sounds different like mine its probably compressor surge from all the bends in the FMIC pipe putting back pressure on the turbo and causing a little flutter. its normal for both though. your gonna have a little surge unless you make your piping as strait as possible which no one wants to do.
I'm having this same issue. Will switching to an aftermarket bpv such as TurboSmart Kompact Plumback or just regular TurboSmart Plumback fix the flutter noise? I'm only running 16 psi with TD05 18G, cobb intake, turbo inlet, tbe, UEL header/up pipe and a tune.
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Old 11-29-2012, 03:17 PM   #23
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even with a forge BPV on the softest spring I got a similar noise but it doesnt happen at WOT, only on part throttle releases. stock BPV did it worse actually. at WOT the forge makes a ping.

your likely just hearing it because you have a CAI installed
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Old 11-29-2012, 04:34 PM   #24
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Quote:
Originally Posted by kamafnkazi View Post
I also have fluttering on my 06. I just installed a fmic, intake and turbo inlet hose.
Also when driving normal when i let off the throttle i get a little hesitation normally under vacuum but also under boost if i dont shift.

From what I hear from friends is that the stock re-circ valve shouldnt flutter.

mine fluttering coupled with the hesitation when letting off the throttle makes me think something is wrong.

The off throttle hesitation usually happens when FMIC's are installed without adjusting the Boost Error Tip in Compensation Table.
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