I installed a TurboXS MBC but it is only running pressure off the wastegate: 7psi. I'm guessing I have my lines run incorrectly. Is there a correct way to bypass the pc and wg solenoids to run an MBC? Thanks in advance.

Jimmy

 

Unless I miss my guess, if you are running Non-Sequential, you shouldnt have those solenoids....

 

WTF??? you do need the wastegate actuator, how else would you control boost???

you are just suppose to wire the PC open and install the MBC between the turbo and the wastegate solonoid. have it fully open and go for a WOT run, then close the mbc a bit and do another one, you should slowly see boost rise as you close it

 

Check this thread out, it will explain it how to install your MBC and alot of other things you might need to know...

 

An actuator is different from a solenoid.

 

Yeah FORSAKEN is right, you need to put the MBC between the turbo and the wastegate actuator and plug the nipple going to the stock boost solenoid.

 

Put a line from one of the nipples on the compressor housing of the primary turbo (pressure side) to the "in" side of the MBC, then put one from the "out" side of the MBC to the wastegate solenoid.

This is how I set it up. It bypasses the stock boost solenoid completely.

Start with it all the way open and slowly close it to get the desired boost level. Make sure you account for different weather, i.e. if you tune for 10 psi on a hot day, it might go up to 12 on a cold day.

 

The thing that confuses me about his setup is when it was converted to full non-sequential, there is no more rat's nest, and no more vacuum lines running to eithher his pre-control or wastegate solenoid on the UIM....and I know every non-seq. I have done, has one of those two hooked up to vacuum sources, and the other is capped off.

No matter how tight he turns the MBC, it will never go over 7psi. With the MBC on or off, the car still only boosts to 7psi. Could the above paragraph have any correlation with this?

 

Did you cap off the remaining nipple on the wastegate actuator? Actually I don't think that would keep boost that low. If you have the boost controller setup right then it should theoretically work, heck My car is working this way right now.

 

Here's the image...

 

Good pic.....yeah, that is how she is hooked up. Everything works and all....just won't get much boost. It only goes up to about 7-8psi even with a MBC. I think one of his BOV's are leaking...because you can hear a very loud swoooshing sound while boosting coming from that area....and it sounds the same as when the BOV releases between shifts. Going to try swapping those out and see if that doesn't help the boost or at least quiet the sound.

 

Should we have the MBC hooked up between the compressor nipple and the wastegate actuator and simply cap the second nipple on the actuator? or should we leave the compressor nipple line running to the wastegate actuator and hook the MBC up to the second nipples on the actuators?

I have one friend with the MBC....can't get above 7psi....and another with the Profec Spec II and also can't get above 7psi unless he creeps past it...both are hooked up to the secondary nipples on the actuators and both have the compressor nipples still running to the two actuators. The second nipples are T-d together. What is wrong?

 

You are intercepting the amount of pressure the wastegate diagragm sees, thus you put the MBC line between the compressor outlet nipple and the vertical upper wastegate inlet nipple, then cap off the lower horizontal nipple to allow the wastegate to open.
Art

 

I'm running my car non-seq without the solenoids. At first I was only getting 7 Psi just like you. But I looked over my lines and found out that I hook up the line from the wastegate that is supposed to be capped off. Other than that I'm running 10 psi no problems. I also had a MBC.

 

These silly twin turbo cars.....I just don't understand them. Singles are just so much easier....thanks Art, we will try swapping those over tomorrow and see if we can't get his car back to boosting properly again.

 

I was just thinking a possibillitie, the little cap that closes the other side nipple of the wastegate might not be very tight, leak a bit, thus not alowing pressure to be crated to keep the wastegate closed so is letting pressure to escape and the wastegate opens before it should, as set by the MBC
Just a thought...