The ones i capped are the ones going to the intake (which isn't pressurized). This is the line that air gets vented through to control boost. By capping off the output of the EBC, it thinks it's still working, it sees an input pressure (since it's still connected to the pressure line), but it can't actually do anything. (since it's plugged).

 

This sounds similar to the Subie. On the Subie, there's a line that goes from the compressor side to a tee. One end of the tee goes to the wastegate actuator and the other end goes to the electronic boost solenoid. The line exiting the boost solenoid dumps into the intake. It sounds like the Evo's the same.

So basically, I'm sticking the MBC in between the tee and the wastegate actuator, correct?

I kinda got lost looking at Noize's pics.

 

The problem is that venting that pressure off of the solenoid gives it a place to escape rather than pressing on the wastegate. This is the point of wastegate duty cycle mapping when tuning the ecu; by increasing WGDC you are telling the solenoid to stay open longer and seep out more pressure that would otherwise go to the wastegate and force it open, causing boost loss. You are hurting your boost curve by doing this, and as I recommended before I would reconnect that line.

 

No, the line's i capped are what the ebc uses to vent pressure, (which will increase boost). With the ebc up and functioning, the car makes too much boost with a mbc. So you have to either disconnect the ebc's, or plug the line they use to bleed pressure. You can plug the line before, or after the ebc, the pressure in the system will not be affected. However if you plug it after the ebc, the ebc's still see an input signal, so they will not throw a cel.

Or am i missing something? I'd love to leave the stock ebc's hooked up, but if i do i run way too much boost.

 

Ahhh, I get what you are saying now. So you were overboosting before you plugged the vent line from the solenoid and now all of the bleed off is done with the mbc. That makes sense, but I wonder if maybe instead of capping the vent line completely if maybe you could put a bleed pill in the vent line after the solenoid (between the solenoid and the intake) to allow the solenoid to bleed off a tiny bit of pressure (much less than stock) from the wastegate so as not to cause overboosting but perhaps maintain a bit better boost at high rpms. This might improve the taper. Hmmm... What do you think qubit?

 

Well, i kept this setup because it's extremely easy to remove the MBC if i need to take the car to the shop. My boost curve appears to be similar to what other people have, 24psi to 17/18 at redline. However, next time i'm working on my car i will eliminate the ebc's completely, and run it without the pill's to see if the boost curve changes.

I think you're right, though. Having the ebc's hooked up *should* give a better boost curve.