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Thread: A long chirp or whistle under boost

  1. Top Of Page | #11

    Re: A long chirp or whistle under boost

    Quote Originally Posted by Batmobile_Engage View Post
    From the video, the sound seems to be completely different than what I expected. Am I right in saying it sounds a little like blowing over the neck of a glass bottle? It almost sounds like a high-frequency, metal-on-metal vibration that is reverberating into the cabin. It reminds me a little bit of when I had a turbo go bad years ago. But it sounds even more like a slightly loose heat shield or like my aluminum skid plate, when my header used to vibrate against it at certain rpms/engine loads.

    I'm very hesistant to suggest turbo bearing failure, car sounds are just so hard to diagnose on the internet.

    Is this your first turbocharged car?
    Yes first turbo charged car.
    It is more like when your trying to whistle and it doesnt go right kinda.
    I have breeze clamps fot the intake tract, I will be doing those this weekend. I should check for exhaust leaks while I'm under there.


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  3. Top Of Page | #12
    Eats rice, drinks V8. Batmobile_Engage's Avatar

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    Re: A long chirp or whistle under boost

    Another thing to check... have someone rev the engine while you are looking around under the hood. If you don't notice the same noise in this case, then we at least know that there has to be a load on the engine for the sound to manifest. Which, while pretty basic, at least helps us understand the issue a bit more.

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  4. Top Of Page | #13

    Re: A long chirp or whistle under boost

    Quote Originally Posted by Batmobile_Engage View Post
    Another thing to check... have someone rev the engine while you are looking around under the hood. If you don't notice the same noise in this case, then we at least know that there has to be a load on the engine for the sound to manifest. Which, while pretty basic, at least helps us understand the issue a bit more.
    There has to be a load on the engine. The video is with the car running an E60 blend. I'm at an E17 blend now and it seems to have somewhat subsided or at least require more load to get the whistle. Not as loud either.


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  6. Top Of Page | #14
    Eats rice, drinks V8. Batmobile_Engage's Avatar

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    Re: A long chirp or whistle under boost

    Good to know. Thanks

    Man, this is a weird one. Do you have a stock or upgraded fuel pump?

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  7. Top Of Page | #15
    Eats rice, drinks V8. Batmobile_Engage's Avatar

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    Re: A long chirp or whistle under boost

    Can you datalog fuel pressure for us?

    This is straight from Cobb (in regards to the flex fuel kit):

    Fuel System Considerations
    As with other DIT platforms i.e. VW, BMW, Mazda, the fuel pumps in Subaru DIT vehicles are not designed for ethanol use beyond 10-15%. That said, ethanol levels between 15-30% are generally well tolerated. Those comfortable with mild risk can run ~E30 and enjoy improved knock resistance, charge air cooling, and a mild improvement in engine power potential. While you can't get E30 at the pump, pumping a combination of E0/E10 gas and E85 in an appropriate ratio will allow blending of a near E30 mixture in your tank.
    On DIT platforms not set up for flex fuel from the factory, at greater than 30% concentration, ethanol has caused oscillating fuel pressure first, progressing to loss of fuel pressure, high pressure fuel pump damage, even making the vehicle inoperable in some cases. Sudden loss of fuel pressure can cause sudden loss of acceleration, stalling, which can reduce braking performance and steering control. Long story short, while the power potential is very attractive, use of high ethanol content fuel is at your own risk.

    COBB has performed internal testing in multiple geographic locations with different fuel sources in addition to compiling data from COBB retail shops, our Protuner network, and customers. Results varied significantly. Some users ran several tanks of E85 in a row without issue while some experienced serious loss of fuel pressure in as little as 1-2 tanks of fuel.
    We suggest monitoring fuel pressure for oscillations. After having fuel pressure issues, some users were able to flush the HPFP (high pressure fuel pump) out with low ethanol gasoline and get it to operate normally again, while others had to replace the whole pump assembly before they could safely drive the car again. After replacing the pump some users experienced repeat failures if they continued to run E85 fuel.

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  8. Top Of Page | #16

    Re: A long chirp or whistle under boost

    Quote Originally Posted by Batmobile_Engage View Post
    Can you datalog fuel pressure for us?

    This is straight from Cobb (in regards to the flex fuel kit):

    Fuel System Considerations
    As with other DIT platforms i.e. VW, BMW, Mazda, the fuel pumps in Subaru DIT vehicles are not designed for ethanol use beyond 10-15%. That said, ethanol levels between 15-30% are generally well tolerated. Those comfortable with mild risk can run ~E30 and enjoy improved knock resistance, charge air cooling, and a mild improvement in engine power potential. While you can't get E30 at the pump, pumping a combination of E0/E10 gas and E85 in an appropriate ratio will allow blending of a near E30 mixture in your tank.
    On DIT platforms not set up for flex fuel from the factory, at greater than 30% concentration, ethanol has caused oscillating fuel pressure first, progressing to loss of fuel pressure, high pressure fuel pump damage, even making the vehicle inoperable in some cases. Sudden loss of fuel pressure can cause sudden loss of acceleration, stalling, which can reduce braking performance and steering control. Long story short, while the power potential is very attractive, use of high ethanol content fuel is at your own risk.

    COBB has performed internal testing in multiple geographic locations with different fuel sources in addition to compiling data from COBB retail shops, our Protuner network, and customers. Results varied significantly. Some users ran several tanks of E85 in a row without issue while some experienced serious loss of fuel pressure in as little as 1-2 tanks of fuel.
    We suggest monitoring fuel pressure for oscillations. After having fuel pressure issues, some users were able to flush the HPFP (high pressure fuel pump) out with low ethanol gasoline and get it to operate normally again, while others had to replace the whole pump assembly before they could safely drive the car again. After replacing the pump some users experienced repeat failures if they continued to run E85 fuel.
    If your wondering if any part on the car is stock, yes. FF kit and AP are the only mods.
    Fuel pressure is solid. I had a log from the video run but in my haste i forgot to select RPM...give me a list of what you would like to see in a data log and I will get one. This kinda sucks being my first turbocharged car, first season change with it (going from 100* down to 45*, first time running ethanol, first time tuning an ecu, and a weird noise that isn't a common tell. Well at least this experience will go on record for the next guy/gal.

    Log: https://datazap.me/u/gantz/log-15477...zoom=5800-5895

    Last edited by dden4012; 4 Weeks Ago at 08:23 PM. Reason: Added log

  9. Top Of Page | #17
    Eats rice, drinks V8. Batmobile_Engage's Avatar

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    Re: A long chirp or whistle under boost

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  10. Top Of Page | #18
    Drinks beer! HolyCrapItsFast's Avatar

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    Re: A long chirp or whistle under boost

    when it does this, does the power surge in response to the noise or is it consistent through out a run?

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  11. Top Of Page | #19

    Re: A long chirp or whistle under boost

    I would say it runs consistently throughout the gear run. No sag or surge in power. Another odd thing is the RPM marks that the noise occurs during, the sweep through 4k and 5k RPM. This is a very consistent variable.

    I changed the clamps to breeze clamps and snugged the turbo housing couple clamp gently. Went for a test drive and thought all was well, no more noise. After some moderate beatings, no noise, I decided to go add some ethanol. Ended up at E57. Got into some boost and sure enough, at the same rpm spots, a much fainter shorter noise of same tone. So i kinda fixed it lol.


  12. Top Of Page | #20

    Re: A long chirp or whistle under boost

    Could this be the hpfp whining about ethanol? I haven't read anything about a noise in relation to this cam driven pump. Its definitely coming from the front drivers side and quite possibly from up top. I'm sure the hoses are on correctly and tight with breeze clamps. TMIC wasnt cracked or coated in oil. None of the intake pieces had an oil residue. As far as the way it drives, its beast for stock trim. I know there is an ethanol approved HPFP for a pretty penny but I cannot for the life of me find it, it was a HPFP and DI injectors package.


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