Why cant I boost past 12psi

[HyperGSX]

Check the profile for mods. I cannot boost past 12 psi even with my mbc opened all the way! It's getting so frustrating. I have no boost leaks either.

 

[Mike Marnik]

You could possibly have a boost leak. can you do a boost leak test? if so do so and post the results.

 

[BlueTurboSpyder]

It could be a number of problems:

1. Boost Leak
2. Bad wastegate actuator
3. Bad wastegate flapper
4. Bad mbc

I had a problem simular to this and it was caused by the wastegate actuator not being able to completely close the flapper all the way. Also, try doing a search.

 

[aadperformance]

Is the MBC installed properly?

 

[HyperGSX]

seems to be connected fine

 

[ddavisaf]

Here is the diagram on howto hook up the boost controller.

Next, run a boost leak test using soapy water. Test from the Turbo inlet and the throttle body. You want your system to hold 20 psi for a minimum of 30 seconds.

At what rpm does your car hit full boost of 12 psi?
Considering you're running the T-25 still it should be under 3k rpm. Anything above this indicates a pre-turbo exhaust leak, a boost leak, or an issue with your wastegate flapper.

So, here's the lowdown.

-Ensure correct installation of the MBC
-Boost Leak Test
-Check for Pre-Turbo exhaust leaks (ie. exhaust manifold/turbo to manifold mounting surface)
-Check the wastegate and make sure it is not being help open. This could be caused by either an old turbine housing that has significant cracks, or a bent bracket.

Now, if your car is spooling normally...

-Disconnect the vacuum source going to your wastegate and plug/cap the opening. This will hold the wastegate CLOSED. Meaning your boost will be unlimited so be very attentive while attempting this test. Run to car and see if you're able to build more than 12 psi. Make sure you stop it before you reach 20 psi otherwise damage could occur. This would indicate a faulty MBC.
-If you're still able to only build 12 psi, it indicates a uncorrected boost leak or exhaust leak, or a faulty turbo.

Post your results.

 

[HyperGSX]

where is the diagram?

 

[ddavisaf]

http://www.dsmtuners.com/forums/showthread.php?t=201941

It's being ignorant.... Check out that link. It's pretty much a whole thread about how to hook up a mbc in which oldman smacks me around and calls me susan.