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Turbo hiss & blowoff?


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Guys, I'm plenty mechanically savvy but I'll be the first person to admit that from a deep technical understanding I'm not really familiar with how the turbo setup is done on the 2.5's. With that out of the way, I've started hearing what I believe is a new noise under the hood of the LGT. I started hearing it last week after replacing the air filter, but I don't think that's related, I think it's just coincidental that I noticed it after the fact.

 

Basically it's a very faint hissing noise that builds when accelerating under a load, then when you let off the throttle you hear a slight "PSSSH". Reminds me of my buddies aftermarket blowoff valve on his Eclipse only this is very very subtle. Almost imperceptibly so. The kicker here is that it only happens under a load. If the car is in neutral you don't hear it ever... regardless of how light or heavy you mash the throttle.

 

Thoughts or suggestions? I get the feeling that this isn't anything earthshattering but I don't like new noises. :)

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Totally normal to hear some turbo noises.

 

You probably just never noticed it before

[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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It's possible, but I doubt it, but my hearing is pretty acute. I had aspirations of being a music major in a former life... when I was younger and before I realized that such a degree wouldn't likely pay off. This isn't the normal whine of the turbine. Even the wife noticed it.
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Normal operation my friend does your Legacy have any aftermarket parts namely Up pipe and/or Down pipe or intake/inlet? If so, these parts, while not harmful, increase the audible noises the turbo makes while building boost.

 

Also the type of filter used can emit more turbo and diverted boost, that hiss noise you hear when shifting or when you get off the gas.

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Nah, completely stock, and the car isn't new to me. I'm the original owner.

 

Your explanation about the type of filter would certainly make sense though, esp. considering I just changed it but this filter was the same as the last. That said, it's clean vs. jammed full of crap like the that came out. I had figured, or hoped atleast that it was normal but again since I hadn't noticed it before I figured I'd ask. Have enough going on right now with a newborn at home than to have to worry about something shelling out on the car.

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Do you still have your old one? Reinstall it and see if the noise goes away.

 

You did reinstall the filter cover correctly, right?

[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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I don't still have the old one. :( Went out with the trash on Friday. The airbox is a mother "B" on these things, but I've checked the hose fittings and the fit of the box and all of the little tabs line up, etc. i.e. the tabs on the bottom are hooked in place. I may pull the whole thing back off and do it again just because.
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Like BAC5.2 said it is normal. I'm guessing something isn't right with the install of the air box.

 

I could not hear mine until I modified the box by removing the lower silencer. If you remove both ends of the hose from the box to the intake, it's much easier to play around in there.

 

I removed mine yesterday to wash and re-oil my Perrin panel filter. I found it easier on my 09 to remove the nut from the inside of the front air box piece, where on my 05 it was easy to stick the 10mm socket in from on top of the head light and remove the nut from the front.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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I also removed the MAF sensor and cleaned it with a dry Q-tip and also the air temp sensor that is part of it. I did get a CEL when I restarted the car, by read the codes and reset the ecu with my Cobb AP. You can reset the ecu by removing the negitive battery cable for a few minutes. If you decide or need to do that.

 

I posted my short story in the what did you do to your 4th gen.... thread.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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