Loud Hiss by TB, boost leak? can't pinpoint

[turbotsi92]

I just rebuilt my engine, and it will not stay running on its own, I have to keep on the gas, I have a loud hiss right around my throttle body, but I can't pinpoint the leak, or atleast I think it is a leak. Just wondering if a boost leak could cause the car to stall?

 

[hewhoisknot]

yes.. most definitely can... if ur elbow is on tight and the tb is tight to the manifold then it's ur shaft seals... time to pull it off and replace those suckers

 

[GSEclipse06]

bad tb gasket? have u removed the tb recently?

 

[skelly]

It's probably something between the butterfly plate and the head where vacuum is present. Leaks before the TB plate are indeed "boost leaks", but not "vacuum leaks" it sounds like you've got a significant vacuum leak, and it could be as simple as a cracked or missing vac hose. Sometimes if you use your hand to deflect the sound, you can figure out where the sound is coming from as the nearer you get to the source the more the sound will change. This might be a little difficult to do though if you have to manually open the throttle plate to keep it running. Another thing to check is the idle air set screw which has a an O-ring on it that can leak. The should be easy enough to isolate by covering the hole with a finger and see if the sound stops.

- SK

PS: there are a BUNCH of EGR-related vacuum lines that connect together just below the TB, so don't forget to check all that.

 

[MindBlowin03]

You might wanna check your TB o-rings as well.

 

[bigblock]

if the post above do not fix your problem look at the fuel injector seals i spent a whole day looking for my leak the injector seals had shrunk, check slowboyracing.com $10 for 4

 

[turbotsi92]

I removed all my emissions lines, and the egr a long time ago, so I know it is not that. I just rebuilt my engine so all the gaskets are brand new, but I for some reason didn't get a TB to manifold gasket, so I had to buy a cheap one at advance. I checked all the vacuum lines I could, and the ic piping, it all seems to be tight. The injector seals are new as well. Does anyone think that cheap gasket could be the problem? I appreciate all the repsonses.

 

[turbotsi92]

yes.. most definitely can... if ur elbow is on tight and the tb is tight to the manifold then it's ur shaft seals... time to pull it off and replace those suckers

What are you talking about shaft seals? I am not sure what you are referring to.

 

[skelly]

What are you talking about shaft seals? I am not sure what you are referring to.

The TB has a plate that rotates on a shaft which passes through the firewall side of the TB to a spring-loaded armature connected to the throttle cable. That shaft has seals around it to keep pressure differential (whether vacuum or boost) from attempting to equalize with the outside atmosphere. It requires a partial disassembly of the TB to replace the seals and they are available for only a handful of bucks from machv.com if you end up needing them. But just the elbow and TB being "tight" as "hewhoisknot' suggested is not enough to go on to undertake that procedure.

- SK

 

[sherwinz28]

I am going through this exact same thing!! Download the second video on my post here:
http://www.dsmtuners.com/forums/showthread.php?t=185372

What I did on that video was spray carb cleaner around the throttle body and walla I found where the leak was coming from. My leak was aparently large enough to cause idle instability. I had to hold the gas to keep the car running. So I took the throttle body off and put new gaskets(why are the gaskets so crappy, thin in certain areas). I also put black RTV gasket maker all over both gaskets and let it sit for, well its been 2 days now. You only need to let it cure for a few hours but I like to give it a day just in case. If this doesnt work I'm going to sand down every piece that needs a gasket from the intake/TB/TB Elbow. I have a feeling it may not be meeting flat.

 

[VBGSX]

Wow, all these suggestions but not one person told him how to test everything for problems

As everyone has suggested, a leak can definitely cause the issues you're having.
Do a boost leak check:
http://www.vfaq.com/mods/ICtester.html
Do not just listen for the leak. Get yourself a spray bottle with a soap and water mix inside it. Spray everything(everything on the TB( vacuum hoses, gaskets, BISS screw,etc), IC couplers, BOV, injector seals, etc). You will see and hear the bubbles that the pressure will create. Do not go on sound along. There are many leaks you will never hear.
Good luck

***edit***
oops one person just did. Although spraying everything with WD-40 isn't the best way unless you like a greasey engine.. It will work to some extent but you will still miss a lot of leaks that way.
The best way is a boost leak test with soap and water mix

 

[turbotsi92]

Could not really hear because of the belt sqealing.

 

[turbotsi92]

Wow, all these suggestions but not one person told him how to test everything for problems

As everyone has suggested, a leak can definitely cause the issues you're having.
Do a boost leak check:
http://www.vfaq.com/mods/ICtester.html
Do not just listen for the leak. Get yourself a spray bottle with a soap and water mix inside it. Spray everything(everything on the TB( vacuum hoses, gaskets, BISS screw,etc), IC couplers, BOV, injector seals, etc). You will see and hear the bubbles that the pressure will create. Do not go on sound along. There are many leaks you will never hear.
Good luck

***edit***
oops one person just did. Although spraying everything with WD-40 isn't the best way unless you like a greasey engine.. It will work to some extent but you will still miss a lot of leaks that way.
The best way is a boost leak test with soap and water mix

thanks alot, i will do that

 

[sherwinz28]

That was the first video...watch the second video. I fixed the belt squeeling in that second one.

 

[bigemrich]

I have a similar problem, but mine isnt significant enough to not idle...let us know how you find the leak so I can try it, haha

--Kyle

 

[turbotsi92]

I have a similar problem, but mine isnt significant enough to not idle...let us know how you find the leak so I can try it, haha

--Kyle

The throttle body gasket was leaking, and the first injector 0 ring was as well. sorry it took so long to post.