Boost leak ?

[ALP584]

I recently purchased a sbr mbc. I installed it correctly tied in all connections with zip ties to make sure it doesnt leak , well when I was done with the installation , I took it for a spin and no matter how I set the mbc it boosts past 17 psi almost to 20psi and it doesnt feel like it pulls hard more like the power is going away car is a 91 tsi awd 5spd with 77,000 miles all maintanence done , has a boost gauge and mbc. Im doing a boost leak test I just wanted to see if a boost leak would cause this since I never had this problem on my fwd dsm.

Thanx

 

[hereitcomes]

You might be getting boost creep, as in slowly moving up the boost pressure...and not having a lack of boost (boost leak). The creep would build up and seem like a loss of power like a boost leak.

 

[steve]

Unless the car was also boosting as described before the install of the MBC it's clearly not boost creep.

I expect one of two things are going on. The MBC was installed the wrong way or it's defective. You can test the MBC by connecting an adjustable air source to the input and raising the pressure until the MBC valve opens. That pressure is about what the MBC will hold your boost at.

Connecting the pressure source (the nipple on the j-pipe) directly to the wastegate will show you if the problem is not in the MBC.

Steve

 

[ALP584]

Well I did a boost leak test at the turbo , and also at the throttle body. Did not find any boost leaks other than the blow off valve leaking at 16-17 psi which I think is as good as it gets on a 1g. Also the mbc does have a little hole in one of its inlets which lets air out but
that is what its suppossed to be I plugged that hole up when I did the boost leak test . After all was done I hooked everything back up just to have the same problem again, and the car before the install boosted around 11 psi stock. The boost slowly goes up and creeps to 22 psi no matter how I set the boost controller.

any input is appreciated

 

[Dieselboy]

Most MBC's have a bleeder hole in them, so don't worry about that. Do you have the MBC hooked up properly? Bottom nipple should go to your boost source, middle/side nipple goes to wastegate.