OK I hate to start a new thread on this but I HAVE searched and there are thousands of pages of junk to sift through to possibly find an answer to this dilemma I am in. I am getting tuned at Pruven in two days and can't figure this one out so since time is a factor I am starting this thread. Anyway here is the problem:

I have the Hallman Pro RX MBC and it is not even holding stock boost. With the soft spring it will hold about 12psi fully cranked down (max boost) and with the stiff spring I only hit 15psi. I do NOT have a boost leak. I know for two reasons. One, I did the usual test by putting one of those ebay tools on the turbo with gauge and connector for your air compressor. It held solid like a car tire. Second reason is when I adjust the WGA preload the car will hold well over 23 psi WITHOUT the MBC hooked up to the car. So again, no boost leak.

I have the MBC hooked up right. Nipple right below the knob to the boost source and the one 90 degrees to that to my WGA. I capped the nipple on the boost solenoid that was originally connected to the WGA just like on Hallman's how-to. I have the MBC T-ed into my BOV to intake mani line because I have a Buschur LICP and it does not have a nipple like the stock outlet pipe.

So in short, it seems everything is perfect. The ONLY thing I can figure is it is the stupid ceramic ball although I dont see how that could cause the problem. There are many guys on this forum running the Pro RX and holding over 20psi. I have checked everything and if anyone has an idea I'm open to hear it. Sorry so long but didnt want to answer a thousand questions so I tried to give all the details of the situation.

 

PS: I did not reuse any stock lines with those stupid pills either.

 

So your saying with it fully turned to the right and with the heavy spring its only boosting 15 psi? I have the same MBC and i use the soft spring wich holds boost great

 

You are correct. I have no clue. It has to be something. This isnt FN rocket science either so wtf? It took me a couple hours to install my 10.5, O2 housing, LICP, and FMIC Monday night but this damn BOV is taking longer to trouble shoot than all that! Very frustrating. Worse comes to worse I hope Pruven can figure it out before I get on the dyno.

 

Bump for frustration. There has to be something I am overlooking or there has to be somebody out there who has simply got a bad MBC and once it was swapped everything was fine. I dont know though, mine is not clogged at all. I dont know if the spring or ball is getting stuck or something, but any help/thoughts would be appreciated.

 

i had a similar problem with my mbc. if you try turning the controller to the left (negative boost) does your boost go down? My knob on my controller actually cross threaded so i have to use pliers to change my boost. I was unable to either increase or decrease boost. If that's not the problem try checking the spring and make sure it isn't getting stuck. just my .02 hope u fix ur problem. lataz

silva

 

hmmm.....

did u use new vaccuum lines?

does the valve have the proper hole in the side outlet barb? there should be a little hole there.....

as long as the ceramic ball comes out when you completely unwind the cap, and go to remove the spring from the bottom, i cant see it binding... if it did, youd see excessive boost.

I have installed 3 of these in the past week on evo's (all ix's)... and have T'd from the bov line on each one (we normally use a compressor signal line) and have had no issues...

I did run the soft spring in mine, and even with it cranked down, i wouldnt see more than 18psi really, so i went back to the stiff spring and it is working fine at 21psi...

hmmmm

cb

 

Boost seems to stay the same but the knob does go up and down when you turn it. Unless the knob is just unthreading itself. Hmmm....I never thought of that. I am going to try and take the knob off and then adjust the boost with pliers when I get out of work. That might be it! Thanks!!!

 

YES

YES, AND AIR FLOWS THROUGH IT JUST FINE.

EXACTLY. MORE BOOST RATHER THAN LESS.

YEAH THAT SEEMS TO BE THE NORMAL WAY TO DO IT WHEN YOU DON'T HAVE THE LICP NIPPLE TO USE SO I KNOW THAT IS ALL GOOD.

I THINK THE KNOB MIGHT BE STRIPPED. I AM GOING TO LOOK AT THAT ASAP WHEN I GET OUTTA WORK. THANKS FOR THE INPUT GUYS.

 

OK, I went out and got the thing outta my Pathfinder and took the knob off. The thing wouldnt spin in either direction. I took some pliers and cranked on it pretty hard and it just broke loose. Now the thing seems to move up and down perfectly. Before what was happening is I thought I was cranking the boost up by cranking the MBC knob down and all I was really doing is seating the knob on it's rod rather than bottoming out due to the spring being fully compressed. I would put a lot of money on the fact that when I get home this thing will work now and so will my car. Good thing 'cause I'm leaving for Milford, CT right after work

 

/\ sweet....that makes perfect sense. Although when I would have came to your place and looked at the mbc I probably would have seen that the adjustment knob wasnt where it should be after rotating it.

Hope this works for you...its a good feeling to be 100% finished...

 

Well I won't be 100% done until I put the MBC back on the car and install my fuel pump. But assuming this does the trick (and it will) then I will be ready to roll very shortly after work. Fuel pump shouldnt take too long to do at all. Hell, we can do it in the parking lot of the hotel tomorrow for all I care.

Thanks to speedfreak0920 for pointing me in the right direction.