Boost leak test results and questions

[Ottoman]

I did a boost leak test recently...

on a home cig light plug type compressor, i couldn't get over 5.5 psi... i wasn't sure if it was the compressor not pushing enough or a leak not letting it go more...


so i got pissed..

drove to the gas station, stopped right in fron of the air hose popped the hood, yanked off the intake, tossed on my boost leak tester.. and filler her up i got the gauge to read 20psi

after around 12-14 psi... i hear this echoy air rushing/hissin sound from inside the throttle body... is this normal? when i open the TB plate it changes the sound... i gropped around the oustide and couldn't feel nothing... is the plate not sealing the air and that's why it's getting past? or is it something else?.. the sound only appears in higher pressure levels.. and when i take the pressure source off... the boost falls quickly down to 10 and then slowly falls after that till finally hitting zero

could this be related to my fuel cut problem?
as soon as my T-25 hits 15psi i fuel cut... how can this tiny turbo be maxing out 450CC injectors? :S or am I outflowing the 2G MAS? (i thought this thing flowed 400HP)

i have a turbonetics Manual boost controller, when i disconnect the BCS.. i go 12 PSI, with the BCS in it's around 15-16... i want 14!! but the MBC just can't seem to hold it... i didn't plug the nipple on the tubine housing... could that cause the MBC to not function correctly?

opinions ideas please

thanks

 

[wyominghotwheel]

i would say yes, that is the best point for boost refrence.............hotwheels of turborides

 

[Attack Eagle]

the throttle body uses o rings (thank god) instead of brass bushings.

sounds like one/both of them is bad...

vfaq has the procedure I believe.

replace them and you should not have the leak, and you will probably have to adjust the MBC again.

 

[Ottoman]

these tiny o-rings can cause this much grief??

 

[44pirate]

these tiny o-rings can cause this much grief??

Yes they do and when you go to bigger injectors it gets worse for setting a good idle.

 

[Mike000]

i have a turbonetics Manual boost controller, when i disconnect the BCS.. i go 12 PSI, with the BCS in it's around 15-16... i want 14!! but the MBC just can't seem to hold it... i didn't plug the nipple on the tubine housing... could that cause the MBC to not function correctly?

opinions ideas please

thanks

How is your MBC hooked up? It sounds like you have a boost leak from that nipple if you left it unplugged.

 

[Jeff_Jeske]

The O-RINGS commonly leak. My two 2g TB had the same problem. I installed a 1G TB with new rings from the hardware store and walla no more leaks.

 

[Ottoman]

The O-RINGS commonly leak. My two 2g TB had the same problem. I installed a 1G TB with new rings from the hardware store and walla no more leaks.

did u notice a gain or improvement in anything?? like no more fuel cut, or stronger pull etc etc

 

[Jeff_Jeske]

I never had fuel cut .... The reason I did a test is because my car was jerky in between shifts. I had multiple leaks not just the one at the TB. After fixing the leaks the car ran MUCH smoother but I couldn't really tell if there was more power or not.

I used soapy water in a windex bottle to locate all the leaks. I sprayed the area where there was a hissing sound and looked for the bubbles. Worked like a champ.

 

[Attack Eagle]

you can use a "poo boys" mechanics stethoscope (sp?) when you boostleak test.

just hold one end of a vacuum hose to your ear and use the other to probe for leaks.

particularly great for those behind the intake hoses on the 2g.


when you get near the leak you will hear it whooshing in your ear.

 

[Ottoman]

I never had fuel cut .... The reason I did a test is because my car was jerky in between shifts. I had multiple leaks not just the one at the TB. After fixing the leaks the car ran MUCH smoother but I couldn't really tell if there was more power or not.

I used soapy water in a windex bottle to locate all the leaks. I sprayed the area where there was a hissing sound and looked for the bubbles. Worked like a champ.

i can hear it clearly.. i tried the windex bottle method.. soaked the whole bloody area.. but i don't see any foaming...

 

[CyberEye]

I need to make an intake leak tester soon. Damn boost/vac leak

 

[Reese92tsi]

You dont have the nipple of your compressor housing plugged up!!!!!!!!!! You MUST put a vacuum cap on the nipple of your compressor housing. That is why you are hitting fuel cut at just 15 psi. You can buy vacuum caps at any auto store.