light flutter noise when accelerating

4475 Views 6 Replies 2 Participants Last post by Rustydawg, Dec 31, 2018

Rustydawg

Discussion Starter · Dec 31, 2018

I have a new flutterying noise, very quiet, not quite the same noise as the turbo spooling up, there may be a decrease in power during the fluttering noise its hard to tell, it happens around 10-12psi if i had to guess, it may be the turbo and I making it all up in my head, but I am wondering if my internal wastegate is doing something it should'nt or is opening too early before the tuned 16.5 psi, also wondering if I should just reflash the current tune and have the ECU maybe unlearn whatever it may be. or maybe its just a sound I am hearing as I am listening to the car more clearly now that I have owned it for 8months and can understand some of what I am hearing more. If a relearn/reflash is not the answer what is, if anything is indeed wrong.

current build
2005 Forester XT
VF39
07 sti tmic
stp intake
cobb 3" down pipe
stage 3 pro tune
set for all the mods and 16.5 psi (except for the intake, but I have re-flashed since putting it on)

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mosquitocoils

· #2 · Dec 31, 2018

Rustydawg said:
current build
2005 Forester XT
VF39
07 sti tmic
stp intake
cobb 3" down pipe
stage 3 pro tune
set for all the mods and 16.5 psi (except for the intake, but I have re-flashed since putting it on)

You haven't listed what you're using for boost control, so I'm assuming you're using the stock solenoid?

My 3 port controller (MAC) makes a noticeable fluttering noise with my VF48 as I get into higher boost/approaching target boost as it starts venting excess boost pressure. It's kind of an on-off-on-off-on-off scenario many times per second, so it gives you that ts-ts-ts-ts-ts-ts and much louder/more noticeable than the stock 2 port controller.

I was going to originally suggest your wastegate actuator but that really only applies to the stock TD04, the VF series turbo actuators are fine and non adjustable anyway.

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mosquitocoils

· #3 · Dec 31, 2018

Or the other thing is it could be an exhaust leak, if you're feeling down on power then possibly up pipe gasket?

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Rustydawg

Discussion Starter · #4 · Dec 31, 2018

Its ecu and the stock vf39 internal wastegate, i beleive the normal spring from the stock vf39 as well, i did a quick data log this morning and at 16.61 psi i have 82.31% wastegate duty. My tune is supposed to be 16.5psi, does this mean Im "peaking", I was thinking it might be just a normal noise as I get close to max boost but wasnt sure it was normal. Furthermore ive only notice it when I hold the boost to around 10-13, again thats a guess but probably close.

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Rustydawg

Discussion Starter · #5 · Dec 31, 2018

Ill check for an up pipe leak or just tighten things down, its possible. Thanks for the suggestion.

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Rustydawg

Discussion Starter · #6 · Dec 31, 2018

Well if there is an up pipe leak it is super faint and hard to tell. Is there a easier to tell other than trying to see fumes from underneath and from above?

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Rustydawg

Discussion Starter · #7 · Dec 31, 2018

I guess i could tighten it up and see if it makes a difference?

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