Help finding the boost leak

[DSMGary]

So i did a boost leak test after my car started to stumble during boost (sometimes). I found that cyl 3 & 4 injector seals are leaking. But i can also hear a hiss from below the throttle body. Not sure if this is the EGR leaking? Is is suppose to?

 

[BigBeans]

Put soapy water all over the TB.

It'll bubble where it's leaking. Chances are it's the shaft seals.

 

[LiquidX]

If you didn't do the soapy water to start, do the whole test over again and spray everything down. Not all leaks make a noise. When you fix the leaks you should be able to hold at least 20 psi for a minute depending on how well your internal seals are.

Chances are it's the shaft seals that are leaking and be sure to rotate the throttle plate when doing the test as the shaft seals can seal in a closed position but leak in an open position.

 

[DSMGary]

soapy water all over the place...thats how i found the injector seals leaking. loads of small bubbles after spraying it. I did spray the throttle body, biss and did rotate the butterfly, the leak (the hiss) was unfound. I could hear it, but could not find it using soapy water. It sounded like it was coming from around the throttle body or even slightly lower than that(which is what leads me to believe it might be EGR?).

 

[LiquidX]

The only other things that would leak at the TB when pressure is applied is either a bad o ring for the ICS, or a bad "o" ring for the lower half of the TB but that would allow coolant to leak into the intake though.

Remove the upper IC pipe and test directly at the TB and if need be, remove the battery to get a better view of the lower porting of the TB.

 

[DSMGary]

The EGR is located on the #4 intake manifold runner, not the TB. The only other things that would leak at the TB when pressure is applied is either a bad o ring for the ICS, or a bad "o" ring for the lower half of the TB but that would allow coolant to leak into the intake though.

Remove the upper IC pipe and test directly at the TB and if need be, remove the battery to get a better view of the lower porting of the TB.

Thanks man, That sounds like a great idea, I will pressurize just the TB. If i get a chance, i will try it today...

 

[LiquidX]

I meant to edit the post before it was re read. Go and spray the EGR and see if it is in fact leaking. I got confused on the location of it.

 

[target12]

If all else fails, you could make a block-off plate for the purpose of leak testing. Thats if you can't see any bubbles.

 

[empie1]

Sounds like the tb shaft seals...I had the same problem and spent HOURS searching before i realized it was the shaft seals.

 

[DSMGary]

If all else fails, you could make a block-off plate for the purpose of leak testing. Thats if you can't see any bubbles.

I will be blocking the EGR off soon. As for the boost leak, it is the seals of the TBshaft. I was able to hear it when i connected the BLT on the TB elbow. Time for a TB rebuild

 

[Below Ambient]

did you check the BOV flange for leaks?

 

[target12]

Time to switch to a non-turbo throttle body I would say. Larger bore and no electrical changes.