boost leak problem

[99 gst spyder]

i did a boost leak test yesterday and found two boost leaks.....one is from one of my injector(not sure why) and one is from under the throttle body(not sure where exactly).. but i did boost leak test over 18 psi and drop pretty quick.....
-could it be the seals between the inj. and the head....i can hear air coming out of the inj, but while that is going on, i push down the inj. the air shut's off till i let go of the inj. and air will still come out of that inj.
-i'm not exactly sure where the leak is coming from but i can hear it under the throttle body...anyone know anything about this leaking...?could it be the gasket the needed to be change??

thanks

 

[habitatguy187]

Yes it's your injector seals, either lower or upper. As for the tb leak it could be shaft seals (more probable for a 1g), it could be your egr valve, fiav gasket, lots of things. Good luck.

 

[matthewdesigns]

Break out the windex and see where it bubbles. It's the only way to be exact.

For the TB, I've got money on the ISC o-ring if it's a big leak, shaft seals if it's small. You can get an ISC o-ring at the hardware store...just take the ISC in and find one that fits (ISC is attached to the TB under the TB elbow...a kinda beige plastic attachment). A way to test the TB shaft seals is when the system is pressurized, rotate the throttle by hand. If you hear a change in the airflow from that spot, then it's the shaft seals. If you've pulled the TB recently it could be the seals b/t it and the manifold or TB elbow.

If an injector is leaking air then it's the lower seal/insulator. The top seal/o-ring keeps fuel in the rail. That's a bad leak . First make sure your rail bolts are tight (8-9ft/lbs is spec)...do not overtighten them! If it still leaks, the insulators are about $2 each from the dealer, and are an easy swap. Search here for how to do it if you don't already know.

 

[99 gst spyder]

thanks guys....i will check the lower and top seal of the inj. and try that throttle open and close to see how the shaft seals are...

 

[No_Skillz]

Windex is too expensive. Use some dishwashing detergent and water. Bubbles a little better too.

 

[habitatguy187]

thanks guys....i will check the lower and top seal of the inj. and try that throttle open and close to see how the shaft seals are...

I don't understand how opening and closing the throttle will determine it's shaft seals, because when you open and close the throttle the sound is going to change anyway because the air path is changing. Could someone explain just exactly how shaft seals will sound different than just opening the throttle plate?

 

[matthewdesigns]

The change to the airflow path is what you are hearing (changing the shape of the shaft seals), assuming that there are no other leaks on/near the TB. The rotation of the TB shaft, and increased spring pressure, change the way the seals are deformed. Even though the spring on the TB shaft is a clock spring, and may not appear to exert any side-side force on the shaft end, it does. And when the seals are almost 10 years old, they can't keep sealed against the pull of the spring.

I have no other leaks in the vicinity of the TB, except for the seals, and I can hear the airflow change when the throttle shaft is rotated. Typically less air escapes around the shaft when I do this test on my car.