Broken mbc?

[dealz]

my mbc doesnt seem to be working right i tried boosting more so i closed it all the way and did 1.5 turns and it read 8 psi(which is what i do normally) then i closed it all the way and it went to 25psi with major fuel cut offs.i oppened it a little bit and it was back at 8psi WTF any suggestions.. thanks

 

[GSTdude06]

Get it back to 8psi and turn it about 1/4turn and see what that does...it could be a boost leak so you should boost leak test first and fix any leaks you might have.

 

[dealz]

Get it back to 8psi and turn it about 1/4turn and see what that does...it could be a boost leak so you should boost leak test first and fix any leaks you might have.

i have no leaks in the pipes but not sure if the mbc can leak ill try the 1/4 turn and see what happens thanks


edit: ok i have new results it goes from 8psi open all the way and 25psi closed all the way and 10 psi anywhere in between.

 

[GSTdude06]

Did you just listen for leaks? Or did you soapy water test? Check the TB and Manifold and BOV and when you boost leak test turn the mbc all the way down or it will bleed out the bleeder hole.

 

[oldman]

Which MBC and how is it hooked up, details please.

 

[dealz]

Which MBC and how is it hooked up, details please.

i have no idea which mbc it is it has no brand and i got it for free but here are pics. its hooked up from the wastegate to my j pipe.

 

[spooling 1g]

i think its supposed to be tee'd to the line on the bov and then to the watsegate.the one on the j-pipe gets capped off.

 

[dealz]

i think its supposed to be tee'd to the line on the bov and then to the watsegate.the one on the j-pipe gets capped off.

i think it might be connected right because it works if you close it all the way. is there any site that shows how it should go connected?

 

[luvmygst]

Where did you get it? It looks to me like it is a "bleed off controller" If it is its hooked up wrong. That would explain full boost when closed, it is blocking the signal to the wastegate. I have seen these type of controllers, even useed one, but I dont reccommend one, they are bad for boost spike before the boost settles down. Can you take one of the ends off and see what it looks like? Does it look like its just a valve to control air or does it have a ball and spring?

 

[dealz]

Where did you get it? It looks to me like it is a "bleed off controller" If it is its hooked up wrong. That would explain full boost when closed, it is blocking the signal to the wastegate. I have seen these type of controllers, even useed one, but I dont reccommend one, they are bad for boost spike before the boost settles down. Can you take one of the ends off and see what it looks like? Does it look like its just a valve to control air or does it have a ball and spring?

ill check and post a pic, if it is a bleed off contrller how should it be connected?

 

[dealz]

sorry about not posting sooner but it is a valve that controlls it. and i think it is leaking where the hose goes over it (the copper tube) is loose

 

[oldman]

sorry about not posting sooner but it is a valve that controlls it. and i think it is leaking where the hose goes over it (the copper tube) is loose

Get yourself a reliable ball & spring type mbc, boost level isn't something you want to play with.

 

[MrBoxx]

I agree. Hallman, Joe P., TurboXS, or even a decently home-made one would probably be better than that one.

 

[chanley talon]

What the heck is that . Hahah Its got a turn stick on the top off it . You should tie it into the blow of vavle vaccum line . Plug the hole on the turbo outlet . Run the other to the wasgate . Your controller that is currently installed is built wrong. It needs to be a ball and spring operated to be most effective .

 

[chanley talon]

Here check this site out it will show you how to build your own.http://www.xmission.com/~dempsey/perform/grainger.htm

 

[oldman]

You should tie it into the blow of vavle vaccum line . Plug the hole on the turbo outlet .

MrBoxx?

 

[MrBoxx]

Oldman wants me to tell you that you should not tee into the BOV line. Leave Mister BOV alone, he likes to keep his vaccum line all to himself so he can operate properly, with no boost leaks caused by pesky MBC's. Use the compressor housing nipple or a nipple on a metal lower intercooler pipe. The results are much better.

And here's why:

Taking the pressure source from the j-pipe fitting has many benefits.

1. The main reason why alot of mbc instructions and some tech articles suggests to tap from the BOV line is because it's connected to the intake manifold, the argument is that this is more accurate because it's the same pressure the engine sees. In reality this is a non issue because the boost gauge is tap to the intake manifold no matter where you tap your mbc so there is no advantage in tapping the bov/manifold pressure as previously thought.

2. The proper functioning (opening and closing) of the bov depends greatly on the accuracy of the pressure in the vacuum hose you're thinking of tapping on or off boost so it's best to leave it connected directly to the manifold without any interference.

3. Tapping off the compressor/j-pipe offers the shortest vacuum hose route which greatly reduces the chance of boost spike.

4. In the case of boost leaks, tapping off the compressor/j-pipe will help prevent over boosting the turbo.

5. Hooking up a bleeder type mbc like the TurboXS standard mbc to the bov line will result in a vacuum leak as well as affect the working of the BOV.

-as originally posted by oldman

 

[MrBoxx]

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[dealz]

Oldman wants me to tell you that you should not tee into the BOV line. Leave Mister BOV alone, he likes to keep his vaccum line all to himself so he can operate properly, with no boost leaks caused by pesky MBC's. Use the compressor housing nipple or a nipple on a metal lower intercooler pipe. The results are much better.

And here's why:

so it is connected properly right? its just a bad mbc.

 

[chanley talon]

Buy tapping into the blow off vavle line you get a constant vaccumm on the mbc /until it boost/ and blow the ball through the mbc pass the air relif hole in the mbc. This is on a ball and spring setup. However i ran one before just of the turbo j pipe nipple to the wasgate. It was never real accurate till i swicthed to the blow off vavle line. Your mbc is not a ball and spring setup its a bleed thefore the way you have it hooked up is the best way . If you get a ball and spring mbc the ball end will tap into the blow off vavle line the other will go to the wasgate acuator.

 

[chanley talon]

Heres another site telling you how to build your own i will also find a install site .http://www.geocities.com/chmwatson/FAQs/mbc.html

 

[chanley talon]

There is an installl picture at the bottom of this same site. You can tap it how you like however i dont have a nipple on my intercooler pipe to tap into . That doesnt mean it wouldnt be better though i havent tried that and i may see if it more effective. But the easier route is to tap into the blow of vavle line . If you find that not tapping into the blow vavle works best for you than im all for it.
http://www.geocities.com/chmwatson/FAQs/mbc.html

 

[oldman]

MrBoxx, you're nuts. How did you get my picture anyway?

There is an installl picture at the bottom of this same site. You can tap it how you like however i dont have a nipple on my intercooler pipe to tap into . That doesnt mean it wouldnt be better though i havent tried that and i may see if it more effective. But the easier route is to tap into the blow of vavle line . If you find that not tapping into the blow vavle works best for you than im all for it.
http://www.geocities.com/chmwatson/FAQs/mbc.html

Ball & spring or bleeder, like already said, leave the BOV line alone. If you don't believe, run a pressure test and see how much pressure you'll be loosing through the ball & spring mbc wastegate pressure relief hole located at the out fitting of the mbc. This unequal pressure between your UICP and the BOV vacuum line coming from the intake manifold means your BOV is most likely opening prematurely when under boost, all other possible side effects aside.

 

[chanley talon]

The only reason it should leak is if you installed it backwards. The hole is blocked by the ball bearing.

 

[chanley talon]

Just use your j pipe ! to wasgate. But get a better mbc