Is there supposed to be a "Hiss" from the Intake Manifold?

Does it by anychance sound like leaves blowing around? I have a noise like that in my car, when im driving around it kinda sounds like leaves blowing around the ground.

Hmm not so much. I cant hear it inside the car at all, only when I open the hood when its idling

check your vaccum lines, garantuee one of them is unhooked. also look for tears or cuts and rips in any of the lines.
how does the car run aside from the noise?

My 90' Talon makes the same noise, but ONLY at idle, there are NO boost leaks and I replaced every possible line and adjasent fitting in the engine bay? I figure the next step is to take the t-body off, take it apart and clean it.

emocore_racer said:

check your vaccum lines, garantuee one of them is unhooked. also look for tears or cuts and rips in any of the lines.
how does the car run aside from the noise?

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Car runs good but I am just concerned. Ill check in the day light every vaccum line around it.

Don't forget about the vacuum lines running underneath the intake manifold. Another common leak near that area with these cars are the throttle body shaft seals. You can pinpoint them with a boost leak test.

Would a loose vac line be affecting my performance at all?

White91TalonTsi said:

Would a loose vac line be affecting my performance at all?

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Depends on the size of the leak. At boost, your vacucum leak now becomes a boost leak which can cause your car to run rich, stutter, stall, etc.

Any sort of boost leak will hinder performance, so they should be corrected. I would suggest doing a boost leak test as well, to see if you have any other issues.

Try pinching the vacuum lines to see if the hissing stops. If it still hisses then its probably your intake manifold gasket.

Darksyne said:

Another common leak near that area with these cars are the throttle body shaft seals. You can pinpoint them with a boost leak test.

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Is that an easy fix or does it require a TB rebuild/replacement?

When I did my leak test it felt like air might be coming out around that area, but with the elbow to TB gasket leaking, figured I'd fix that first to make sure it wasn't just air blowing onto that area from the faulty gasket.

Guess if its not a simple replacement, now might be the time to upgrade.

Whiplash said:

Try pinching the vacuum lines to see if the hissing stops. If it still hisses then its probably your intake manifold gasket.

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Uh oh....that sounds expensive

Intake manifold gaskests are $13

dsmquest said:

Intake manifold gaskests are $13

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Theres probly alot of labour involved though right?. Maybe not if this is my case

Orange Crush said:

Is that an easy fix or does it require a TB rebuild/replacement?

When I did my leak test it felt like air might be coming out around that area, but with the elbow to TB gasket leaking, figured I'd fix that first to make sure it wasn't just air blowing onto that area from the faulty gasket.

Guess if its not a simple replacement, now might be the time to upgrade.

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T-body shaft seals are pretty cheap...But I hear they are hard to get from the factory...There is another thread about it somewhere here and the people posting on it have extra's and they are giving them away! Go find the thread and score some shaft seals...They're probably worn anyway

Yes, TB seals require a rebuild. I got mine done by a guy on DSMLink forums for $50. Yeah you can do it much cheaper yourself but I didn't feel like messing with it. Another common leak in that area is the BISS (Base Idle Set Screw). You can get a replacement one from the stealership pretty cheap and it includes the O-ring. I think you can also get just the O-ring, but I don't remember.