Topic: Flutter sound when accelerating under boost

[carcar123454321]

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

[Sol Asylum]

Does it continue to build boost or does it just plateau?

Stock intercooler, hoses, and clamps?

[Uranium-238]

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?

[carcar123454321]

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.

[Sol Asylum]

It could be a weak spring on the BOV allowing it to unseat or the valve itself could have an issue.
 

[carcar123454321]

I think I'll try the spring first.  Can I just "stretch" it to see if that helps first?

[DeepBlueGXP]

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

[carcar123454321]

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).

[carcar123454321]

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. 

[Critterman]

Glad you found and fixed it.