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Old 04-27-2013, 04:17 AM   #1
dmg44
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Default Weird hissing sound at 4k RPM

My car is a 2010 Wrx Sedan.
My only mods right now are a CBE and COBB Ap Stage 1 93.

Recently, I just started hearing a constant high pitch whistling/hissing sound coming from the engine bay when I am WOT at 4k. Sounds like an air leak. I've had my data logs reviewed by a tuner friend and he said there is no obvious boost leak and that the car appears to be running healthy.


Here is a video of the actual sound of me doing WOT in 2nd at 3k rpm and the hissing kicks in around 4k until I left off the gas, and then continues while I'm WOT in 4th.

Any idea what is wrong?
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Old 04-27-2013, 04:51 AM   #2
Coreycarlile911
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The hiss of your turbo? Sounds pretty normal
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Old 04-27-2013, 01:03 PM   #3
dmg44
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well it didn't have that sound a few months ago. And I don't hear it on other WRX pull videos.
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Old 04-27-2013, 01:56 PM   #4
Cathexis
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Have you checked you intercooler clamps, i assume you took it off to get to the back bolt ehen you installed your dp. Details are in my reply to your other post on this issue.
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Old 04-27-2013, 03:33 PM   #5
dmg44
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I haven't installed the dp yet. I've never touched the intercooler on this car.
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Old 04-27-2013, 07:01 PM   #6
Coreycarlile911
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Quote:
Originally Posted by dmg44 View Post
well it didn't have that sound a few months ago. And I don't hear it on other WRX pull videos.
Well with stage one and catback you are running bit more boost and the aftermarket cat back is a tad less restricted. Idk just sounds like the turbo doing its job to me. How long have you been on the stage1 map?
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Old 04-28-2013, 02:19 AM   #7
dmg44
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about a month now

I checked all the clamps and hoses and everything seems to be snug.

Now I think about it, I first heard the noise right after installing my turbo XS CBE. My mechanic friend noticed the noise too and said that turbo is louder because its more free flowing. I am just bothered because I don't hear it on other WRX's with stage 1 and 3" CBE.

Last edited by dmg44; 04-28-2013 at 03:13 AM.
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Old 04-28-2013, 06:50 AM   #8
Cathexis
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If you didnt replace the dp you likely wouldnt hear anything from the turbo because of the restrictive cat. I had issues getting my dp on so i drove around for awhile with a cbe. Once i got the catted dp on, i only just could hear some turbo whine, no hiss. The only hiss i get is from the cold air intake. Have you checked the mating of your cbe to stock dp for a possible leak. Will be really easy to spot if you've been hearing it for a month, it will have black carbon streaks where its leaking. I ditched the spring bolts for a more traditional, tight fitting, nut and bolt.

If thats not it, do a log. Log a third gear pull, and do a short cruise log. Post it on google drive or better google docs, make it public, and let's take a look at your fuel trims.

Last edited by Cathexis; 04-28-2013 at 07:03 AM.
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Old 04-28-2013, 10:07 AM   #9
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Quote:
Originally Posted by Cathexis View Post
If you didnt replace the dp you likely wouldnt hear anything from the turbo because of the restrictive cat. I had issues getting my dp on so i drove around for awhile with a cbe. Once i got the catted dp on, i only just could hear some turbo whine, no hiss. The only hiss i get is from the cold air intake. Have you checked the mating of your cbe to stock dp for a possible leak. Will be really easy to spot if you've been hearing it for a month, it will have black carbon streaks where its leaking. I ditched the spring bolts for a more traditional, tight fitting, nut and bolt.

If thats not it, do a log. Log a third gear pull, and do a short cruise log. Post it on google drive or better google docs, make it public, and let's take a look at your fuel trims.
I'm pretty sure I hear more turbo just from adding the nameless muffled axleback. A new noise has started since the install at full boost... Kind of a low pitch hiss...
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Old 04-28-2013, 06:59 PM   #10
Coreycarlile911
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Quote:
Originally Posted by C3hutson View Post

I'm pretty sure I hear more turbo just from adding the nameless muffled axleback. A new noise has started since the install at full boost... Kind of a low pitch hiss...
Yea that's most likely what your hearing. You could do a log and make sure boost and everything is up to par but from the video it doesn't sound like you have anything bad going on.
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Old 04-28-2013, 07:39 PM   #11
bootystank
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if your that worried do a smoke test. But when im on the highway i hear my turbo hiss/whine from 2500 to 4500 rpms and i Can make it louder of quieter just with my foot
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Old 04-28-2013, 09:03 PM   #12
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Yea I also recently started noticing a hiss after stage one map and namless axleback. Think its fine as long as your not over boosting or anything
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Old 04-28-2013, 09:38 PM   #13
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Quote:
Originally Posted by Cathexis View Post
If you didnt replace the dp you likely wouldnt hear anything from the turbo because of the restrictive cat. I had issues getting my dp on so i drove around for awhile with a cbe. Once i got the catted dp on, i only just could hear some turbo whine, no hiss. The only hiss i get is from the cold air intake. Have you checked the mating of your cbe to stock dp for a possible leak. Will be really easy to spot if you've been hearing it for a month, it will have black carbon streaks where its leaking. I ditched the spring bolts for a more traditional, tight fitting, nut and bolt.

If thats not it, do a log. Log a third gear pull, and do a short cruise log. Post it on google drive or better google docs, make it public, and let's take a look at your fuel trims.
I just had my car on the lift today while we were installing my dp and I noticed an exhaust leak from the stock dp to turbo xs cbe. After going stage 2 today and fixing the leak, I don't think I hear it as much. But I wasn't paying attention because I was too distracted by how awesome stage 2 is and the new sound of my catless downpipe. But I'll post my log in a few days.
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Old 04-28-2013, 10:07 PM   #14
Cathexis
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Awesome!!!
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Old 04-29-2013, 06:32 PM   #15
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Thanks for all your help!
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Old 07-25-2016, 08:40 PM   #16
Red2011sti
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I had this exact same noise coming from my CBE. After doing an extensive inspection on all of my flanges and ensuring all my gaskets were properly seated I still could not locate any leak. I was beginning to think that it was the flex pip that is located on my midpipe. Anyways, ended up taking it to a subaru specialist and they were beginning to think that it was a boost leak. I honestly did not believe that it could be a boost leak, so in desperation I went back home and installed my stock exhaust system back onto my STI. After the install was done I took it on a few runs and the sound was gone. I have no idea what the heck it was but I am leaning towards some type of leak on the CBE.
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Old 07-26-2016, 10:16 AM   #17
maperformance
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Sounds fairly normal to me,
I would recommend a boost leak test though to see if maybe just maybe, there might be one.

-Leo at MAP
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