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Author Topic: Flutter sound when accelerating under boost  (Read 1061 times)

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Offline carcar123454321

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Flutter sound when accelerating under boost
« on: June 28, 2023, 01:01:56 PM »
I'm cross posting from another forum, but wanted some feedback.

It's a faint sound so you have to listen hard. Note it's not the blow off valve flutter while decelerating/lifting throttle...I'm accelerating ;-). It starts around 12 psi and continues up from there.

  • I just put on a new timing chain and balance chain and all related parts about 9 months ago so I sure hope that's not it.
  • I checked the turbo wheel about 9 months ago too and no play, but may check again to make sure.
  • I'm thinking of seeing if I can get some cheap dyno time (like 5 minutes) to just listen to the noise standing beside the car if possible. I wish I could identify roughly where the sound is.
  • Just got a great deal on a turbo, blow off valve, and wastegate actuator so may just throw all that on. Would rather identify the issue first though.
  • I'm going to log the car and send to my tuner...at least rule out something tune related. I'm also going to slap the stock tune back on but I doubt that has anything to do with it.
It's just a little annoying as I just got the car all back in tip top and it was running so well and pulling incredibly. I feel like I'm back in my Subaru days, having to fix something every 3 months ;-0

Offline Sol Asylum

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Re: Flutter sound when accelerating under boost
« Reply #1 on: June 28, 2023, 01:14:18 PM »
Does it continue to build boost or does it just plateau?

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Offline Uranium-238

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Re: Flutter sound when accelerating under boost
« Reply #2 on: June 28, 2023, 03:18:45 PM »
Is is the BOV just regulating the pressure? Still odd that you can hear it when you couldn't before, maybe it's a sign its on the way out?
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Offline carcar123454321

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Re: Flutter sound when accelerating under boost
« Reply #3 on: June 29, 2023, 11:40:51 AM »
Thanks all:

  • It continues to build boost to 21-22 psi, even with the flutter, but the power definitely seems a little less (like maybe 80% of what it was when first tuned)
  • Aftermarket RPM motorsports IC with T-clamps, DDM silicone hoses (connectors and throttle body)
  • I am wondering about BOV, WG actuator, WG solenoid, etc.


Offline Sol Asylum

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Re: Flutter sound when accelerating under boost
« Reply #4 on: June 29, 2023, 01:14:17 PM »
It could be a weak spring on the BOV allowing it to unseat or the valve itself could have an issue.
 
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Offline carcar123454321

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Re: Flutter sound when accelerating under boost
« Reply #5 on: June 29, 2023, 06:12:45 PM »
I think I'll try the spring first.  Can I just "stretch" it to see if that helps first?

Offline DeepBlueGXP

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Re: Flutter sound when accelerating under boost
« Reply #6 on: June 29, 2023, 06:29:46 PM »
Does it sound kinda like a faint pinging or metal taping noise?  Mine did that under acceleration and it was the chain hitting the guide that is between the overhead cams, it's supposed to have a polyurethane bracket attached to it to dampen the noise and prevent chain lash

highlighted item on drawing, the top #19 item
« Last Edit: June 29, 2023, 06:37:05 PM by DeepBlueGXP »

Offline carcar123454321

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Re: Flutter sound when accelerating under boost
« Reply #7 on: July 01, 2023, 07:58:00 PM »
Thanks all.

I just replaced the timing and balance chains and all guides so hopefully that's not it!  That was quite an undertaking for me ;-)

I have a new turbo with a new BOV so I think I'll try swapping the parts on that to see if that helps.  It's a bit hard to reach the WG actuator and take that all off and I need to order a WG solenoid, but eventually I hope to replace the whole turbo and all associated components (BOV, WG actuator, WG solenoid, hoses, clamps).

Offline carcar123454321

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Re: Flutter sound when accelerating under boost
« Reply #8 on: October 16, 2023, 09:06:21 AM »
I forgot to follow up on this, but it turned out that the fluttering sound was the exhaust manifold / gasket.  I guess the LNF exhaust manifold nuts are known to loosen up and mine were quite loose.  I was able to tighten all of them as I can get my manifold cover off (it's trimmed) using various sockets, extensions, universal joints, etc.   Once tight, there was zero flutter. 

Offline Critterman

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Re: Flutter sound when accelerating under boost
« Reply #9 on: October 16, 2023, 09:07:24 AM »
Glad you found and fixed it.
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