"Shhhh" sound just started happening? - Subaru WRX Forum
 
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#1 Old 09-19-2013, 10:09 AM
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"Shhhh" sound just started happening?

Hi all,

A couple weeks ago I started hearing a hissing, or shhhhh, sound as the turbo starts to kick in around 3K. Sometimes it's worse than others, and I've tried a lot of things to see if I can narrow down exactly when I'm noticing it most. I took it to the dealer yesterday, and 4 hours later they told me nothing was wrong...

I've been digging and researching this problem, and I'm not the only one it sounds like. The only difference seems to by my car is "ok" in the eyes of the dealer. I found a thread that linked to this vedeo:
That's EXACTLY what I hear. Mine just isn't quite that loud usually.

The car is bone stock except for a Cobb AP. When I got it, and after doing some data logging, I settled on the Stage 1 ACN91 HWG map (HWG probably due to my altitude being almost 5000 ft). I now have 8000 miles on it.

I decided to do a little diagnostics of my own hoping that it would help you guys help me get to the bottom of this:

My original data logs (when I originally tuned the car 4-5 mo ago) had a very clean boost curve that peaked at just under 15 and smoothly backed off to about 10. I didn't have time to drive out to BFE to get another set of logs, but I did use the monitoring on the AP to see if I could see anything. Sure enough, when I start at about 3K I hear the hissing sound. Right around 4K I hit almost 18psi boost, then it quickly backs off to 15, then gradually drops back to 10. It NEVER launched over 15 before this problem. I threw the "stock" map back on, tried the LWG and NWG maps and all of them are doing it.

One thing I think I noticed, but haven't verified, is that if I let the car sit for 10-15 min it's less pronounced. Then, after heating the turbo back up I think it gets louder. I got bombarded with texts and emails, so I decided to pull off the freeway and reply. After 10 min or so I ran back up the freeway onramp trying to get a hiss and it was either not there or much less pronounced. After a half mile of fooling around on the freeway it was a bit louder. Again, this hasn't been repeated multiple times, so may have been a coincidence...

Another thing I notice is if I'm full boost and I let of the gas I get a "squeak" noise. I'm almost positive this is just the stock blow off doing its job, but I wanted to throw it in here just in case it's related.

Environmentally, the temperatures have been getting cooler (it's September, go figure), but it's still been in the high 80's during the day, so I don't think that has anything to do with it. OAT doesn't seem to play a role, I hear it all the time.

I've tried all the gears to see if there's any difference. 1st is hard to tell because it's done with so quick. Plus the engine noise gets in the way, but I think I do hear it. 2nd I definitely notice. 3 and 4 it's there as well... and I can even get it in 5th at normal freeway speeds.

One of my first posts here was me wondering if I'd experienced a loss of power. This was very soon after I got the car, and I just dismissed it as me getting use to the power and how the car handled. This may very well still be the case, but it's one of those nagging thoughts that keeps me wondering if this problem "started" way back and has just progressively gotten worse. I just remember right after I got the car that when the turbo kicked in I felt like I was just along for the ride, especially up around 5K. Now when I'm running up an onramp it just doesn't feel the same. All of my data logs from the AP tell me that it was boosting normally and nothing was amiss. Very likely just my experience and perception, but I needed to put it in here.

I'm not a gear head (obviously), but I have done a little work on my cars in the past and generally pick things up very quickly. I really need to learn more about this car so I'm not running to the dealer ever time I hear a new noise. Being in the onsite IT business, I can't afford to be without my car for half a day, especially when they just tell me everything is fine and I'm imagining things. Can someone tell me what I can check and maybe some other troubleshooting steps I can do? Any pictures would be great!

Thanks a lot for all your help. I love this forum!

Last edited by scottay; 09-19-2013 at 11:25 AM.
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#2 Old 09-19-2013, 11:07 AM
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Possibly the clamps on the TB to IC hose are not tight enough causing a sqeak from the air sqeezing out. I had that happen to me and I took it back to the dealer. It happened right after break in because at that point I started to actually drive the car not completely baby it all the time. (mind you I don't beat on my car all the time by any means). The dealer fixed it with no problem at all and I was at 1900 miles on the car when it happened.

Andy - 12 WRB WRX
Tuned by Innovative Tuning
294 AWHP / 311 TQ
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#3 Old 09-19-2013, 11:22 AM
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Thanks for the reply!

Every single post I see on this issue points to one of the hoses not being secure, broken, etc, etc... All hose related... But the dam dealership says all the hoses are tight and fine. Supposedly they had two techs test drive it. How can I check myself? I'm more than happy to unscrew a few things if need be to look at the hoses myself, and maybe even replace the TB-IC hose with a stock or aftermarket one to troubleshoot this myself. I just need to know where to look and how to do it.

Here's another video I found:
Mine doesn't whistle like that, and and it's not quite as loud, but still sounds like the same problem... I don't want to just wait for this thing to get worse, then schedule another appointment a week out, then be without the car for a day. We all know the drill with warranty work. If I can just take an hour or two over the weekend and replace a hose I'll do it in a heartbeat.
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#4 Old 09-19-2013, 05:25 PM
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Don't listen to the techs. Mine told me my turbo was blown, turned out to be the hose from the intercooler to the throttle body, you can tighten them down and them still do it. There are rubber boots that are glued on to each side of the hose, you need to take them off then tighten the hose back on with out those boots on there. It started out like the noise in the video, then one day the boot completely blew out and starting making a noise like when you pinch the opening of a balloon and let the air out. Which indecently sounds very much like blown turbo. I took the techs word for it and replaced the turbo, 8 hours later, same issue. Got a boost leak test done and found out about the hose.

You should take it to a shop and have a boost leak test done, that will let you pinpoint exactly where the noise is coming from.
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#5 Old 09-19-2013, 09:53 PM
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Thanks for the insight!

Two of my clients are auto shops, both with really good reputations in the area. I'm sure I can barter some time with one of them to do a boost leak test

Should I start with just tightening the hoses myself? I think I saw the boots you're talking about. Mine looked like a piece of foam around the end of he hose, but I'm not sure it mine is glued. It has a zip tie down the hose a little, which appears to keep the boot in place? I didn't tug on it or anything, so I don't know if it's glued or not.
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#6 Old 09-20-2013, 06:33 PM
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This is what the boot looks like, and that is what happens to it eventually:

http://img688.imageshack.us/img688/8...0905120450.jpg

Most boost leak tests are about 20-40 bucks, mine was only 20 because we found the leak instantly. I would just save yourself the trouble and get the test done first thing.
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