Backround: stock 1jz with top mount tial wastegate
My problem is that everytime i try to use a boost controller it spikes and i hit fuel cut. I installed (correctly) my greddy profec b and when hooked up i have no control with the settings it just spikes and hits fuel cut. I have tried the overboosting setting and all with the controller still nothing. I installed a friends manual boost controller and same thing fuel cut. I swapped wastegates and it still does the same thing. It seems as if whenever i hook a vacumm line to the top of the wastegate it hits fuel cut otherwise it runs wastegate spring fine.

 

How much boost are you hitting?

 

It hits fuel cut right around 17psi

 

It hits fuel cut right around 17psi wastegate is 10

 

Check the lines. Mind drawing up a diagram of how you connected? It's 99% in your vacuum lines.

 

http://www.fd3s.net/profec_install.html

I used the external wastegate diagram i have also ran the lines about 5 different ways just trying stuff and if i have it hooked up it overboosts and if i pull the line off the top of the wastegate then it boosts 10 lbs completely fine but when the top line is on then it overboosts to fuel cut

 

Depending on the style of MBC (this may also apply to EBC's but I don't own one so I can't say for certain) you need to leave that top port vented to atmosphere. Otherwise, the pressure in the top chamber will not let the wastegate open. If the MBC works well using the bottom port alone, then run it that way.

 

When i hooked up the mbc it hits fuel cut or doesnt work and runs off wastegate depends how i hook it up and if i hook up the ebc with the top port open it just runs wastegate