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Discussion Starter #1
For the life of me I can't figure out why I'm not holding consistent boost with the Turbosmart MBC. So, for a sanity check I made modifications to this pic to show what I did to hook this thing up. I wanted to make sure this is right before I try a new BOV to see if that's it. After that I call the website I got it from and get it swapped out. Thanks for your help.

 

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yes you did hook it up right

your speed6 has a factory boost controler on it did you remove it when you installed your boost controler?

also how high are you trying to run the boost that may be why you are not holding consistent boost

with this little turbo any more boost than factory is just hot air, you are probley loseing hp so you may want to just go back to the stock system till you get a bigger turbo
 

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Discussion Starter #3
yes you did hook it up right

your speed6 has a factory boost controler on it did you remove it when you installed your boost controler?

also how high are you trying to run the boost that may be why you are not holding consistent boost

with this little turbo any more boost than factory is just hot air, you are probley loseing hp so you may want to just go back to the stock system till you get a bigger turbo
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Stock boost controller? Doesn't capping those points bypass that?
 

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Capping those two points should trick the stock boost control.

I also have installed the Turbo smart last week and found that I begin to drop off at 4.5k and then drop another 5 psi until redline. I currently have it set at 16 psi.

Someone mentioned in the Profec thread that it may actually be holding to redline just the location of our boost gauge tap is after our crappy intercooler which looses pressure. I am guessing that if you tapped into the vaccum line between the turbo and the mbc you would see proper boost levels...
 

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I mentioned tapping a boost gauge in that location to avoid the pressure drop and maybe get a more accurate reading to set the boost controller up. Not sure what the verdict was other than they said it would read higher boost levels.
 

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With the stock turbo, that is where I would mount it as well. If our K04 is supposedly maxed out, I'd be concerned more about what the pressure the turbo is giving out than what the the throttle body is seeing. We don't even know the pressure drop of the stock ic, so if we are seeing 17.5 psi after the mbc is set, the turbo could be pushing 1.5psi more than that for all we know.
 

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With the stock turbo, that is where I would mount it as well. If our K04 is supposedly maxed out, I'd be concerned more about what the pressure the turbo is giving out than what the the throttle body is seeing. We don't even know the pressure drop of the stock ic, so if we are seeing 17.5 psi after the mbc is set, the turbo could be pushing 1.5psi more than that for all we know.
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I was considering where to hook my boost gauge up to last night. I just used the line from the intake to the BOV right now but I don;t like using that line since pressure can eb released by the BOV and it may need read as accurate as somewhere else. Thought about that line where the MBC gets hooked up but I may just wait till I get a MBC and then hook both up to that point. Probably also explains why my boost only spikes to around 15-16 then holds at 14.5 or so.
 

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I'll try changing the Boost Gauge tap location tonight and see if that changes how it reads.
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Boost spikes:
Make sure there are no restrictions in the hose to and from the MBC.
Make sure there is no restriction cast into the nipple on the sompressor, or in the inlet to the actuator.

Pressure gauge ....
measure off the other side of the actuator (now plugged) to see if MBC is holding steady.

The solenoind valve
... is just a vent, so once you disconnected the hose to it, it is non-functional. Capping the ends keeps it clean, if needed in the future.

If Pressure gauge holds steady, indicates IC pressure drop at high rpm. Some drop in boost is good, based on ecu's fuel cut map.
 

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Discussion Starter #11
Boost spikes:
Make sure there are no restrictions in the hose to and from the MBC.
Make sure there is no restriction cast into the nipple on the sompressor, or in the inlet to the actuator.

Pressure gauge ....
measure off the other side of the actuator (now plugged) to see if MBC is holding steady.

The solenoind valve
... is just a vent, so once you disconnected the hose to it, it is non-functional. Capping the ends keeps it clean, if needed in the future.

If Pressure gauge holds steady, indicates IC pressure drop at high rpm. Some drop in boost is good, based on ecu's fuel cut map.
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There is a restricter inside the nipple on the compressor, but is removing it necessary? I didn't take a close look at it or know how to remove it.
 

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There is a restricter inside the nipple on the compressor, but is removing it necessary? I didn't take a close look at it or know how to remove it.
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It is needed for oem control system to create pressure drop while venting, but counterproductive to mbc's where you want to pop the pressure to the actuator. causes spikes, may also induce some boost taper. could measure it with "number drills", then carefully drill out to the next limiting hole size (mbc, actuator nipple, etc).

to go back to stock control, make a "pill" from ~1/4" alum rod stock, with that small hole, and insert in hose to compressor.

been there with rx7 FD boost control.
 

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Pressure drop would sure indicate the fuel cut issues if the boost gauge was tapped in at the BOV/reciculation valve and you were setting up the MBC based on that boost reading. Basically meaning if boost is registered at 17psi at the BOV/throttle body it might actually be pushing like 18.5-19psi causing fuel cut past 19psi.
 

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Discussion Starter #14
I wish I could find a good cut away or explanation on how our dual port actuators work. I don't think my gauge will get a good reading off the top of the actuator.

EDIT: Would a better place for a boost gauge be a "T" between the MBC and the turbo? Or would that hinder actuator operation and increase lag?
 

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Pressure drop would sure indicate the fuel cut issues if the boost gauge was tapped in at the BOV/reciculation valve and you were setting up the MBC based on that boost reading. Basically meaning if boost is registered at 17psi at the BOV/throttle body it might actually be pushing like 18.5-19psi causing fuel cut past 19psi.
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The engine should be reading the amount of boost in the cylinders (post IC) so if you have your MBC set at 17psi and your gauge tap'd off the bov, you're seeing the same amount of psi the ecu see's in the motor. It doesn't matter if the turbo is working harder and actually putting out 19psi and the IC is dropping the extra psi, the ecu reads the amount of air in the motor and adjusts fuel accordingly.

If you tap the gauge at the turbo, you'll see a higher psi than what you're actually getting in the engine which will lead you to believe you're boosting X psi when you're actually boosting X-(IC drop) psi.

Jason
 

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I wish I could find a good cut away or explanation on how our dual port actuators work. I don't think my gauge will get a good reading off the top of the actuator.

EDIT: Would a better place for a boost gauge be a "T" between the MBC and the turbo? Or would that hinder actuator operation and increase lag?
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Search this forum for my posts about "vent" or "control" for how it works.

You are right, 2nd nipple is just actuator pressure, but would be interesting to see what it is and if it drops.

The hose looks big enough for a 1/4" hose tee, which should not restrict.

Measure that compressor nipple restriction if you can. Blowing that out should hold boost drop to IC and TB drops ... 3 psi or so with MBC.

For MBC, best to make a tap point at the aluminum elbo, after the IC. If there is a thick spot, could use a 1/8" npt fitting, with 1/4" hose barb.
 
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