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Installing MBC on my vr4
- Thread starter147/1000
- Start date
JCorbo25
Well-known member
From my understanding:
Wastegate -> MBC -> nipple on j-pipe coming off turbo (can also link in the nipple near the BPV like factory)
Wastegate -> MBC -> nipple on j-pipe coming off turbo (can also link in the nipple near the BPV like factory)
Brunoboy
Well-known member
yea and remove the Stock Boost control Solenoid.
JCorbo25
Well-known member
You can tap into the throttle body for a boost source.
Wastegate->MBC->Throttle body
Wastegate->MBC->Throttle body
Brunoboy
Well-known member
Quoting 147/1000:
After market turbo does not have vac line coming off the turbo. I also have an external wastergate. Vac line comes off the waste gate, goes to the factory boost control solenoid then back into the intake pipe.
it should be wastegate--->MBC--->Lower IC pipe or J pipe.
After market turbo does not have vac line coming off the turbo. I also have an external wastergate. Vac line comes off the waste gate, goes to the factory boost control solenoid then back into the intake pipe.
it should be wastegate--->MBC--->Lower IC pipe or J pipe.
Lofty
Well-known member
Quoting 147/1000:
After market turbo does not have vac line coming off the turbo. I also have an external wastergate. Vac line comes off the waste gate, goes to the factory boost control solenoid then back into the intake pipe.
So remove that, and put it where the stock boost solenoid is.
After market turbo does not have vac line coming off the turbo. I also have an external wastergate. Vac line comes off the waste gate, goes to the factory boost control solenoid then back into the intake pipe.
So remove that, and put it where the stock boost solenoid is.
JCorbo25
Well-known member
Quoting Lofty:
Quoting 147/1000:
After market turbo does not have vac line coming off the turbo. I also have an external wastergate. Vac line comes off the waste gate, goes to the factory boost control solenoid then back into the intake pipe.
So remove that, and put it where the stock boost solenoid is.
the intake pipe vacuum port is not the proper one for a MBC, you want a boost source.
You could even hook the MBC up to one of the ports on the intake manifold, but it'd be better to have something closer to the turbo. I'd say the throttle body is the best place if you don't have the j-pipe or UICP.
Worst case, just "t" it into the BPV/BOV vacuum line.
Quoting 147/1000:
After market turbo does not have vac line coming off the turbo. I also have an external wastergate. Vac line comes off the waste gate, goes to the factory boost control solenoid then back into the intake pipe.
So remove that, and put it where the stock boost solenoid is.
the intake pipe vacuum port is not the proper one for a MBC, you want a boost source.
You could even hook the MBC up to one of the ports on the intake manifold, but it'd be better to have something closer to the turbo. I'd say the throttle body is the best place if you don't have the j-pipe or UICP.
Worst case, just "t" it into the BPV/BOV vacuum line.
If you take it off throttle body, make sure it's manifold vacuum that provides positive pressure too (boost) and not one of the ported ones...IIRc, the "P", or nipple closest to front of vehicle should fit this, although it is a small port. I would think coming off the manifold and a larger port would provide better results.
Are you sure you have your MBC routed correctly and not backwards? Can also check your wastegate's diaphragm with a mityvac (vac/pressure) to make sure it's not torn.
Are you sure you have your MBC routed correctly and not backwards? Can also check your wastegate's diaphragm with a mityvac (vac/pressure) to make sure it's not torn.
There's quite a few ways to hook up the external.
Assume this wastegate has a "10psi" spring. If you hook nipple 1 up to a boost source and leave 2 open like it is, you will get 10psi. If you hook up 1 and 2 to a boost source, you will get 20psi.
Because you can do this, I'm not a completely a fan of using a mbc on an external. I spent my mbc money on a couple springs, so I just swap springs and the vacuum lines around to achieve the desired psi.
If you want to run a mbc on this wastegate, you leave 2 open like it is. Then it's:
Boost source | MBC | Nipple 1
Where are you getting the boost source from? You can leave the boost control solenoid electrically hooked up in the car, but there should be no vacuum lines going to it. It's no longer part of the setup.
I got the boost source from the throttle body, port "p". When that didn't work I tried the nipple on the center front underside of the intake manifold by the injectors just to see if it would work. Still nothing. I also tried swapping around the lines on MBC incase I had them backwards. Still nothing. Could the waste gate spring be to stiff?
I have a turbo xs MBC. The boost +/- screw is clearly marked. What is the other screw on the side? Does it need to be all the way in, all the way out, half way or what?
I have a turbo xs MBC. The boost +/- screw is clearly marked. What is the other screw on the side? Does it need to be all the way in, all the way out, half way or what?
Last edited:
A nipple off the manifold is best. A source before the throttle body is fine, but off the manifold gives consistent boost control.
The nipples on the throttle body are too small. Some of those are the size of a pinhole in the throttle body. I only know of people using the P nipple for a boost gauge, otherwise they're always capped off.
Before installing I blow into A and adjust the dial until I'm right at the point air stops coming out of B. Now the MBC is at the starting point of making boost adjustments.
A goes to the manifold.
B goes to the bottom nipple on the wastegate.
The top nipple on the wastegate is open to atmosphere.
If it still doesn't work, I'd say something is up with the boost controller.
The nipples on the throttle body are too small. Some of those are the size of a pinhole in the throttle body. I only know of people using the P nipple for a boost gauge, otherwise they're always capped off.
Before installing I blow into A and adjust the dial until I'm right at the point air stops coming out of B. Now the MBC is at the starting point of making boost adjustments.
A goes to the manifold.
B goes to the bottom nipple on the wastegate.
The top nipple on the wastegate is open to atmosphere.
If it still doesn't work, I'd say something is up with the boost controller.
gramkrakr89
Well-known member
nothing?...
no boost?
no boost control?
Have you tried adjusting the MBC all the way out, so that it effectively bypasses it? you should get WG actuation pressure for boost when you do that.
The bleeder on the side of the boost controller (if there is one) should be fully closed until you understand what it is for.
This external wastegate you have... are you sure you're using the right port?
Having your compressor housing outlet tapped for a boost source nipple would be a good idea.
no boost?
no boost control?
Have you tried adjusting the MBC all the way out, so that it effectively bypasses it? you should get WG actuation pressure for boost when you do that.
The bleeder on the side of the boost controller (if there is one) should be fully closed until you understand what it is for.
This external wastegate you have... are you sure you're using the right port?
Having your compressor housing outlet tapped for a boost source nipple would be a good idea.
Nothing as in no boost control. Right now boost just builds(I haven't let it go past 15psi) until the knock gauge starts lighting up. I have what I believe to be a tial knock off waste gate (it was on the car when I bought it) And the MBC is routed to port 1 as labeled in the pic in the above post.
transparentdsm
Well-known member
A - 1/B - open/turbo outlet - 2, im pretty sure. i may be wrong but i dont think so
gramkrakr89
Well-known member
try hooking the vac hose from the manifold directly to "port 1" on your wastegate actuator, and see what boost you level out at.
maybe u have a 20psi spring? /ubbthreads/images/graemlins/dunno.gif in which case, 20psi would be the lowest boost pressure you can run.
An inline MBC only allows you run more boost than the wastegate spring is rated for.
maybe u have a 20psi spring? /ubbthreads/images/graemlins/dunno.gif in which case, 20psi would be the lowest boost pressure you can run.
An inline MBC only allows you run more boost than the wastegate spring is rated for.
