crazy hissing/compressor like sound

[skrecht]

well, i finally got a resonator on my custom piping to tone down the massive droning inside the car at downshifts and throttle release, and i drove off not realizing a NEW SOUND had emerged due to the sound of heavy rain.
when i floor my car now, i get this loud hissing sound. it is not a sucking air sort of sound, rather as if i have a compressor blowing air underneath my car.
i cannot hear it if i'm parked and revving the car.
could it be a LEAK in the exhaust welding, or could it somehow have affected the BOV settings (a ghetto setup of a turbosmart which i will revert to stock tomorrow as i go to the dealer to address the hissing).
what do you guys think?
I will try to see the dealer tomorrow, but you know how that is, so i'm eager to hear you guys' opinions so i could be a bit more informed when i head in there tomorrow.
Since i will replace the turbosmart BOV with the original, that should help eliminate the BOV as the culprit, but from there, i'm not sure. thanks in advance.

 

[1FASTMSP]

it sounds like its just your turbo at full spool, you probably just could not hear it before because of the exhaust...

 

[skrecht]

i thought it might have been turbo sound masked by the old exhaust setup, but man, our turbos can barely be heard spooling up and this is way way loud "hissing", and i thought that turbo sound is always more of a sucking/whining sound. i'm gonna look in my engine bay and check all piping for any loose ones maybe i'll find something. thanks for your reply. i'll call my msp buddy, who has a stock setup in everything and compare, that's probably the easiest way to find out if the sound is normal and i'm just not used to it.

 

[Striker187]

if it's a hissing sound, i'm not sure if that's the turbo on the exhaust side. on the exhaust side, the turbo sounds something like if you whistled and hummed at the same time.

 

[1FASTMSP]

no, i am talking about the compressor side, mine did this when it was stock...

 

[skrecht]

thanks again guys for the posts, but here's more; even though its a hot FL day, and that takes a toll on the car's perfomance, today is different for on 2nd gear, what i feel is the gear with the best sweet spot and pull, the car is strugling and absolutely doesn't have that feeling of a rush at around 3500 rpm and obove as usual. As for the sound, its exactly like you are adding air to your tires with a compressor, and imagine that compressor leaking. Now that i've noticed the performance drop, i'm getting worried. Another thing to note, the ghetto BOV it has on it usually chiped at around 4000rpm and at higher rpms, it just whoosed, and now there is no more chirp and just a little whoosh. for some reason, i keep thinking that for some reason, i'm losing all the turbo pressure out into the atmosphere through the BOV and since its a piece of crap job by the previous owner, i can't even get to the adjustment without dismantling it. So i can't even play with that. I guess i'll wait to get the stock BOV installed on it tomorrow and see if that takes care of it, and hopefully it does. other than that, i am convinced that this hissing (pressure release sound at mid to full throttle) is not normal for its robbing me of power. thanks again guys and i'll keep checking the post till i go into the dealer tomorrow and figure this out. take care.

 

[1FASTMSP]

sounds more like your turbo is working over time because of a leak from the BOV...keep your foot out of it until you get the other BOV on there, otherwise, you may overclock the turbo and fry it...

 

[jurgs01]

If you had a leaky BOV you would be stalling more than likely, but it doesn't hurt to check. You said they put a resonator in, did they put it in your DP?? Do check the connections to the turbo first (s-pipe, inlet, out). Do you still have the stock plastic piping? Check that to make sure there are no leaks.

 

[Notorious]

if your bpv is still rerouted into your intake, it won't stall even if you are leaking. The air has already been metered by the maf. I would definetly check connections and make sure things arent tight. If you are able I would also do a pressure test.

 

[skrecht]

hey guys, thanks again. i must say that some stuff posted went right over my head for this is the first turbo car i own and its only been mine for two weeks, so i've yet to learn all about it. nevertheless, the issue is really worrying me and i can't wait to get into the dealer tomorrow to figure out what is going on. thanks again and i'll let you all know what was up. take care.

 

[skrecht]

hey guys, a big sigh of relief.........
today i went into a new muffler shop and basically asked the guy to just cut out the resonator and just place another straight pipe as it was. surprisingly, this guy knew what he was talking about.... he cut it out and showed me what he had earlier suspected to be the issue. the "resonator" that was placed in is actually a "turbo tube". I heard "turbo" and thought, 'it must be right since my car is turbo charged", duhhh. Its a misnomer as i found out. the guy told me that that 'resonator' is what he uses many time as a muffler on some cars. he gave me a flashlight to look through the turbo tube ans surprisingly, you can't see through it. its got another tube/chamber system within it..... to cut this short, that tube was creating so much back pressure that the car was performing terribly. so instead of just a straight pipe i went with his resonator, a small tube which yhou can see from one end to another that is slightly narrower in diameter on the inside thatn outside that has some gills on its walls that are supposed to cut down noise. good part is that the car feels so much better than on the turbo tube, downside is that the drone is as loud as ever and so friggin annoying, and i believe there is a small leak which i'll go in tomorrow to take care of. the car seems ok, but i still hear the hissing, though not as loud as before, and the performance is almost what it was before, or that's just my screwed up perception of how much pull the car had. i will post a new thread for the hissing sound, for i'm curious how turbo leaks can be uncovered and if that could be an issue for me. man, i'm starting to get really paranoid about my car since i read that thread with all the problems that people are having. take care guys.