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Old 04-16-2017, 07:14 PM   #1
pony
 
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Strange new sound; ?? vacuum leak or fuel rail??

Hope this is the right section, and feel silly asking, but can't hunt this down. I just installed headers and uploaded a custom tune on my Camaro that has been sitting for the winter. Upon starting, there is now a noticeable sound coming from the left front top engine area; near where a vacuum line that passes over the TB;enters the TB, and the fuel rail check cap. It sounds like a constant loud vacuum leak. This is also no where near the header exhaust/manifold that was done.

The car is running good, no codes, etc. and cannot "change" the sound by moving covering vacuum lines. Considered intake leak, but think it would be running worse, and nothing on this was touched.

ALSO, the engine cover was not installed, and maybe this is a fuel rail sound or other that has always been present, but masked by the cover. Looking for any ideas, or someone that has similar sound and/or can confirm this is normal. Most cars guys know how a "different" sound makes you paranoid. Thanks for any ideas/advice.
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Old 04-16-2017, 07:21 PM   #2
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Can you record the noise and maybe able to narrow down the sound?
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Old 04-16-2017, 07:58 PM   #3
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Originally Posted by Ed805ls3 View Post
Can you record the noise and maybe able to narrow down the sound?
Sounds like a bad tire leak. Best I can get, but the "hissing" does go away slightly when the camera moves away from area.

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Old 04-16-2017, 08:00 PM   #4
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You can take a tube or section of heater hose and hold one end to your ear and move the other end around like a stethoscope; it should help you isolate where the sound is coming from.
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Old 05-14-2017, 10:00 AM   #5
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After installing a catch can and starting the engine with the cover off I noticed the same sound in the same area. Engine runs good and no codes. Thinking it might just be a sound that was always present but muffled by the cover. With the cover on and hood closed it's not noticeable.
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Old 05-14-2017, 02:29 PM   #6
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Quote:
Originally Posted by pony View Post
Sounds like a bad tire leak. Best I can get, but the "hissing" does go away slightly when the camera moves away from area.

try to spry directly a carburator cleaner and see if the idle speed drops.
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Old 05-14-2017, 03:51 PM   #7
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Double check all your vacuum lines again man. Especially near your PCV system. Whatever it is, its a big leak. Whats your normal idle RPM and what is your current idle with this sound?

I don't have any sounds like this, but I am also not running with a catch can.

*Just listened again on 100% volume. Damn, sounds like a lot of air. Surprised you're not having other issues or throwing a code.
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Old 05-14-2017, 09:27 PM   #8
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I would consider removing those vacuum lines for inspection. I had a cracked plastic line (the 1st one you wiggled) on mine. I couldn't change the sound by wiggling, but when I took it off it was clearly the issue. You can replace those with a pliable vacuum hose. I am also running a Catch Can and mine does not make this sound.
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Old 05-15-2017, 01:59 PM   #9
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I'm not the OP and don't mean to hijack, but my car makes the exact same sound. I was expecting to hear that it's normal since there is no code and it idles fine and steady at 5k rpms. I'll try the carb cleaner trick when I get home for good measure.
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Old 05-15-2017, 06:24 PM   #10
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Be careful not to knock debris loose to be sucked in. Just spray smart
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Old 05-15-2017, 06:39 PM   #11
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Quote:
Originally Posted by 15SSRS View Post
I'm not the OP and don't mean to hijack, but my car makes the exact same sound. I was expecting to hear that it's normal since there is no code and it idles fine and steady at 5k rpms. I'll try the carb cleaner trick when I get home for good measure.
.
Not a problem at all. All here for help and answers. Mine continues to run just fine. When I do pull a vac line, it goes to shit. May also try the carb clean to see what happens. Dyno Steve thought it was just air flow and with no codes or idle issues, it was probably just fine. If anything changes, will update post.
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