So I'm trying to set my basically stock IX to 22psi with an AMS MBC. Problem is, I can't get boost UNDER 25-28psi, period. I was told that maybe the wastegate actuator arm was set too long and therefore keeping the WG shut, but I adjusted that to its minimum setting and there's practically no difference in boost. What do you think is wrong? The wastegate inside the hotside itself, the actuator, or what? The flapper moves freely if I push on it.

Thanks guys, I need my car working SOON!

 

Check to make sure the spring inside the boost controller is seated properly.

-Ryan

 

1. is this a new mbc?
2. have you opened it and serviced it?
3. does it come with different springs in the mbc
4. Why does you sig say ebc when you have a mbc?

 

Yeah I'll check that spring

Sorry, haven't changed my sig in a while... Originally we thought the boost controller was the problem, which was originally that EBC, so I bought a brand new AMS one, and that's the one that's currently installed. Came with just one spring.

 

What exactly do you mean when you say that you adjusted the WG to its minimum setting? Are you saying that you shortened the adjustable, threaded actuator rod? How short and compared to what?

 

Because the flapper valve's pivot arm has a cantilevered design, when you shorten the actuator rod it actually tends to keep the valve from opening. Thus, it operates the opposite from what you were told.

In fact, the actuator rod cannot be lengthened beyond a certain point, as long as the turnbuckle on the end of the rod is fitted properly onto the flapper valve's pivot arm. With the rod adjusted to its longest length, the Evo's 16G turbo will see 11-12 PSI not much more.

 

Make sure the Tee you are using doesn't have a smaller diameter on one side, and that your vacuum lines running to the MBC and wastegate also aren't a really small diameter. I had a similar problem and that fixed it entirely. Pressures increase to uncontrollable levels if the Tee or lines are much smaller than the originals.