i have gotten an megan o2 housing installed on my evo 9. when i got it back my boost would spike to 25-30 psi. With the forge boost controller all the way down i replaced my vacum lines for holes and still no response. also tried straight vacum lines together elimating the boost controller to see what would happen and still boosting 25psi. we started playin with the watsegate actuator to see if there was a problem with it but seemed fine. we replaced it with another stock actuator and the problem still was there. my brain is fried trying to find what the problem might be.

Let me know thanks

 

The manifold swap should have no effect on boost.

When you say all the way "down," do you mean the knob is all the way UP, which means the boost is at minimum? If the knob is turned all the way "down," then it's at max. Just wanted to clarify that comment.

How was it boosting before the swap, and who did the swap? If you didn't do it, do you know if they messed with anything in the boost system? Did they remove the MBC and hoses, then re-install?

 

An open exhaust can cause spike quite easily; manifold no... but anything after the turbo sure can. Im curious as to what Warrtalon asked you about who did the install and what they messed with.

Another thing that may be causing your spike is the vacuum lines. Sometimes if they are routed a far ways away and the lines to and from (where did you tap in BTW) are lengthy then that can also cause spike. The MBC should be close with good, obviously non-leaky lines that are as short as possible.

 

Is the MBC installed correctly?

 

hmm my mbc wasn't working right either at one point try taking the top off of the mbc and turning the nut under it manually with some needle nose pliers that fixed my problem