Noise: hissing or air leak sound, notice when in gear under load

Moody03SVT

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Hi,
I have all mods in my sig and have about 25k on her. This deep hissing sound (almost like air leaking) I am hearing is more noticeable when I first start the car up in cooler weather and it seems to be under load when in gear. I can clearly hear it when driving down the road and in a higher gear with low rpms (and exhaust is quiet) and when I give it gas, even with the slightest amount of gas but still under load, it begins to make this noise. I can hear it along with the crisp sounding exhaust, it almost sounds like it is coming from my A-pillar gauges or dash cluster but pretty sure it is coming from engine.

It usually goes away in warmer weather or if I driver her for a long time but recently it seems to be lasting a bit longer before it goes away.

anyway, any thoughts?

I thought maybe
torque differences in eaton to intake,
injectors in cold weather,
or just normal sound....

thanks for any help!!!!
 

Easy

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for a hiss i was thinking injectors too. you should pull them and check them out. maybe try starting it in the garage, where u can hear the sound bounce off the walls. maybe it can pinpoint a location of where its coming from a little better.
 
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Moody03SVT

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that would be a good thing to learn...
What do I look for to determine if an injector is going bad?

if that is what the issue is
 

Crowley

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where do you hear the sound coming from? small leak to your boost gauge maybe? When it warms up, maybe it seals better?

thoughts?

Crowley
 

Moody03SVT

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that is what I thought but while the noise would occur it did not make much difference moving the gauge around or the pod.

It would make sense, because whenever the car is under load there would be an increase in pressure going to the gauge, moving from vacuum to boost

I did not think that could happen... is this a common noise area, that seal leaking?

I hope that is all it is, I won't worry so much :(
 
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Crowley

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87whitevert said:
that is what I thought but while the noise would occur it did not make much difference moving the gauge around or the pod.

It would make sense, because whenever the car is under load there would be an increase in pressure going to the gauge, moving from vacuum to boost

I did not think that could happen... is this a common noise area, that seal leaking?

I hope that is all it is, I won't worry so much :(

I was thinking more about the plastic hose or whatever that connects to back of the gauge ....

Crowley
 

rmgtc01

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That is wierd, is it loud enough to post a sound/video clip?

Is the radio tuned to an AM station. j/k
 

Moody03SVT

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hehe, you know its funny you make that comparison because it could almost sound like static... I don't think it will pick up with the exhaust being so loud.

The sound also comes when sitting still tapping the peddle to rev engine... it first comes on when I tap the gas but if I hold my foot there and it steady revvs at like 2k then it goes away a bit.

I tried removing the gauge from the pillar and checking to see if there was a break in the hose.. nothing, started car up with basically the gauge in my hand and no noise coming from it.

I also popped the hood and put my head next to my heads and revved the engine a bit while still warming up... and nothing unusual for the car, same ticking from injectors and a slight pulley bearing noise but nothing that would account for this.
(but... this was done outside.... I may hear differently if I do it in a garage)
 
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SteveChris

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maybe check your exhaust. i had an air leak sound, not hissing really. but it just sounded like something was off, heard air rushing sorta under the car. it was my prochamber to catback flanges, both sides almost completey held together by their own force of being mashed together. the bolts loosened and knocked right off
 

rmgtc01

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Also make sure your belts are not rubbing against anything. Check the coolant hose, that has been an issue before.
 

Moody03SVT

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that could be it.... and of course exhaust changes once the car warms up.. and that would make sense that I would hear it close to door jams (right around a-pillar and dash vs center of car.)

Needless to say I don't think this is a major issue, like the blower having air leak or a leak in the air intake

On a side note... I am convinced that if I had a quieter exhaust my interior would not rattle so much due to sound vibrations :)
 
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Moody03SVT

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rmgtc01 said:
Also make sure your belts are not rubbing against anything. Check the coolant hose, that has been an issue before.

I did not see anything like that when I had my head in the engine bay listening... just a bunch of idler pulleys with wear and tear on them...:burnout:
I will have to replace some of those stock pulleys soon with my BilletFlow idlers
 
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Moody03SVT

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so... still could check exhaust but it does not seem to be that.
Could this have anything to do with having to change spark plugs?

or oil level in blower snout is low (there seems to be some black soot under the snout and on the front of the blower)
 

FireRed04Vert

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try disconnecting and plugging the boost line for your gauge behind the glove box and see if it goes away. If that doesn't fix it, have someone sit in the car and rev it while you listen in the engine compartment. Doesn't sound like any injector noise I've ever heard of.
 

Easy

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87whitevert said:
so... still could check exhaust but it does not seem to be that.
Could this have anything to do with having to change spark plugs?

or oil level in blower snout is low (there seems to be some black soot under the snout and on the front of the blower)

i dont think it would be the exhaust at all. any exhaust leak ive ever heard ticked, never hissed. the black soot under the blower snout is just some dust from belt wear which is normal unless theres alot.

have you tried a mechanics stethoscope? try one while someone else gives it some gas
 

Moody03SVT

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not Boost gauge, tried disconnecting it and the sound still ocurred.

Now that the weather has been warming up (70's during the day) the sound has definitely reduced when first starting up and warming up. It almost does not happen now.

On a side note, I just replaced what I thought was a bad idler pulley and added a new Gates belt (very very tight fit considering I have 2.76 upper and two 100mm idlers and only the 74" belt) and I have a slight wine when I high rev. Of course I can only hear it when I go to shift and the exhaust is not as loud but its definitely there, it goes with RPM.

BUT she is still kickin' and taking anything I through at her.
I LOVE THE NITTOS!!!!!! NO MORE :burnout:
 
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Moody03SVT

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warmer weather has come and it happens a lot less. It most often does not even happen now when it is really warm out

I appreciate all the ideas being kicked around
 

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