MBC has absolutely no effect!! Boosting 12 PSI full or no boost! PICS

[ivj]

Ok this is sort of a continuation from this thread:

http://dsmtuners.com/forums/showthread.php?t=242780

I installed an MBC, and had a boost leak, loosing all my turbo's power. I bought some tighter hoses, and everything's fine now, turbo's boosting as it used to. However, the MBC has no effect.

Basically, if I unscrew the MBC all the way out (aka - boost to the full or no boost), my car drives just like it always did, the turbo kicks to 12 psi, and i feel the power. My TURBO IS BOOSTING even though it shouldn't!

Now, if I screw the MBC all the way IN (aka full boost) - there's not a single change. The boost is still the same 12 psi, and the car drives exactly the same.

This is how I have it hooked up:

You must be logged in to view this image or video.

Line #1, goes to the nipple coming out of the turbo, right below the inlet.

Line #2 goes to the wastegate actuator nipple.

There were no instructions with this MBC which I got off a friend (and it worked just fine in his car), but from what I've seen online and from all other MBCs constructions, I believe I have these hoses hooked up properly. They're all airtight, no leaks , so I'm kind of lost. Please let me know if there might be an error in my hook up.

The only thing I can think of, is my wastegate actuator is broken, and it's actually running full boost, but my 2g BOV leaks anything past 12 PSI, so my car stays drivable. If this is the case, replacing my wastegate actuator would solve the problem of always boosting, and replacing my BOV would let me go past 12 PSI (15 here I come .

What do you guys think? Any other theories/suggestions? Where can I get the wastegate actuator?

 

[grnchevyz]

It sounds like the MBC to me and not your WG Actuator. 12PSI sounds close to bang on with the WG Actuator nipple to a boost source. Looks like the MBC might be acting more like a fancy vaccuum line connector. If you want to check that, run a vaccuum line from the WG Actuator nipple and T it off on the FPR vaccuum line. If you boost to 12PSI then you know the MBC isn't doing its job.

Looks like you have it connected correctly..one side to WG Actuator and the other to a boost source.

 

[FORMONTOYA]

It looks like a Hallman Pro boost controller http://www.hallmanboostcontroller.com/index.html (or one hell of a good knockoff), and you have it hooked up correctly.....source to the bottom (opposite knob), feed from the side. This boost controller (and most others I imagine) will run boost levels at WG spring pressure when fully opened. It would act like nothings there. When you "turn" the knob in, it should raise the boost.

Your correct that a 2G BOV leaks around 11-12PSI and that's a limiting factor. However, it should still "spike" up to your higher pressure setting before it "leaks" back down.

It doesn't really sound like a WG problem as they're only a spring diaphragm. They usually just work, or not work. But if you know someone close it doesn't take long to swap one out for a try.

On the Hallman...the feed nipple (side) has a tiny pinhole in it and has to be remain in that position. If you managed to swap the nipples (while changing o-rings) it will screw with the controller. Don't ask me how, but that was a big "notice" on the instructions http://www.hallmanboostcontroller.com/files.html (pro series instructions).

 

[Black94DSM]

It looks like a Hallman Pro boost controller http://www.hallmanboostcontroller.com/index.html (or one hell of a good knockoff), and you have it hooked up correctly.....source to the bottom (opposite knob), feed from the side. This boost controller (and most others I imagine) will run boost levels at WG spring pressure when fully opened. It would act like nothings there. When you "turn" the knob in, it should raise the boost.

I have the Hallmon MBC also. With the controller all the way out, I will see 2 more psi of boost over wastegate pressure. For instance 14 psi wastegate pressure, the boost controller will add 2 psi and bring it up to 16 psi minimum.

 

[FORMONTOYA]

I imagine this is a case of "every car's different".

I also run the Hallman "Pro" MBC. Along with it I run the HAHN Super 16 with an adjustable 14-17PSI WG actuator. I purposely set the WG actuator at 16PSI (I knew I could run 16PSI safe in the summer) straight from the turbine housing to the WG actuator and with the MBC turned out it hits 16PSI solid.

With that said.....I imagine we will agree that turned out it should be at it's lowest setting, and turned in increases boost. If in fact it is a Hallman, it should be etched +/- on the knob.

I guess my question would be is the source from the turbo straight to the MBC (no "T" or break/splice in the line? Then the feed straight to the WG actuator (no "T" or break/splice in the line?

 

[ivj]

Yeah the lines are straight, the pinhole is in the place, there's no "spikes" in boost, it's just as if the MBC weren't there. I guess I gotta try this out without the MBC?

 

[JayRolla]

You sure its not hooked up backwards. I had the same problem. Have you swapped the mbc around?

 

[FORMONTOYA]

Yes, the first thing is to check it without the MBC and see what happens.

Even though I'm not a fan of sourcing the MBC from the BOV line.....I have read a few posts where some have claimed that their MBC didn't work properly sourcing from the turbo, but did work sourcing from the BOV. That would be my second "try". Although I personally don't see why one source would work and not the other.

 

[FORMONTOYA]

You sure its not hooked up backwards. I had the same problem. Have you swapped the mbc around?

Of course anything is worth a try. However, it appears to be a Hallman "Pro" series MBC. If that's the case then it does source (turbo) from the bottom (opposite the control knob), and feeds the WG actuator from the side.

 

[ivj]

I guess first I'll give my friend a hard time, and then I'll try going straight from the turbo to the WG actuator. If that doesn't lower my boosts, the WG gotta be broke.

 

[FORMONTOYA]

As with any MBC....you WILL NOT be able to lower the boost any lower that WG spring pressure.

 

[snowboarder3]

I am having a simalar problem. I am boosting up to only 7psi. cranked down only 7 psi.
I am really thinking its my actuator. but could it be a boost leak?

 

[staticbrainwash]

I am having a simalar problem. I am boosting up to only 7psi. cranked down only 7 psi.
I am really thinking its my actuator. but could it be a boost leak?

Boost leak test? Thats an easy way to know if it is or isn't.

 

[Eastwood95]

Why dont you just try another MBC to identify whether your's is good or bad. Sounds like a bad MBC to me.

 

[taylork057]

..is the tiny ball and spring in the MBC???

 

[Eastwood95]

..is the tiny ball and spring in the MBC???

Yeah, those are pretty important to have...