Boost Decrease with MBC install

[JX6]

I just installed the hallman es boost controller i bought.
I connected the post opposite the adjustment knob to a line t'd off the bov line.
I connected the wastegate line to the other port on the mbc.I am running a stock t-25.I need pics of what a stock t-25 looks like on the car and where the lines supposed to go.
I noticed that there was a t fitting on a line going from the compressor housing to the wastegate.I don't know if that is stock or not but i just connected the t'd line to the mbc.
My car was running 11 psi before the install, but now i am running barely 9.
Do I need to cap off the compressor housing nipple just like i did the intake nipple?

If I can I will post some pics of what i looks like.

Also do I turn the adjustment know clockwise or counterclockwise to increase boost?

Any Ideas?

 

[oldman]

You're only running the actuator spring rating because the actuator is connected to both the mbc and the compressor nipple, you're basically bypassing the mbc. My suggestion is to remove the T in the BOV line, connect the compressor nipple to the inlet of the mbc and actuator to the outlet of the mbc while keeping all hoses as short as possible.

 

[JX6]

So thats the mbc install for all 2g's with a t-25?
Why do some people tap off the bov line?

 

[Stapl3]

Boost controller goes between the wastegate and a boost source. BOV line is a boost source. This is basic, basic stuff man.


BOV line is a terrible place to get your boost source from IMO. That line is critical to the BOV keeping shut, and with so many boost controllers having bleed off holes, I can't believe it's the "norm" to take it from there.

In a faily stock setup,

1g's should put one end of the boost controller on the wg, other on the nipple on the Jpipe.

2g's should put one end of the bc on the wg, other on the nipple on the compressor housing.

 

[oldman]

So thats the mbc install for all 2g's with a t-25?

Yes.

Why do some people tap off the bov line?

Because it's been said that it's more accurate because it's the manifold pressure when in reality it doesn't matter because the boost gauge is tapped to the manifold either way. The difference between tapping off the compressor/licp and the bov is a simple twist of the mbc adjustment knob due to the slight pressure drop after IC. In fact, there are several advantages of tapping off the compressor/licp.

1. Greatly reduces the chances of boost spike due to short route pipping.

2. Help prevent over spinning the turbine in the case of boost leaks.

3. Prevents pulling in un-metered/un-filter air during idle in the case of a bleeder type mbc like the standard TurboXS mbc.

 

[Stapl3]

In fact, there are several advantages of tapping off the manifold.

Turbo.

 

[oldman]

fixed.

 

[DiamondStarM]

1. Greatly reduces the chances of boost spike due to short route pipping.

So is this why after installing my my FMIC I noticed some spiking and slightly less consistant boost?

3. Prevents pulling in un-metered/un-filter air during idle in the case of a bleeder type mbc like the standard TurboXS mbc.

I had no idea the MBC was pulling in air, so by tapping into the LICP instead of the BOV line it will stop this?

 

[DiamondStarM]

I pulled up the MBC install from the tech guide and you both make good points about the location for the boost source. Maybe someone can clear this up for me.

Here's what the tech guide says:
You HAVE to use the intake manifold is you want proper boost control. Why is that? The manual boost controller regulates the amount the wastegate is open based on the pressure at its source. Since you want to control manifold pressure, you want the MBC and the WGA to be recieving pressure directly from there.

Using a source off the turbo or intercooler pipe can cause you to have boost that changes with weather, load, and engine speed, and can also slow down boost response. By comparison, a manifold source will be fairly steady, solid, and reliable.

 

[oldman]

So is this why after installing my my FMIC I noticed some spiking and slightly less consistant boost?

Boost spikes and inconsistant boost can be caused by a lot of things, the hose length and pressure source is just one of them. Did you perform a boost leak test after the fmic install? Was anything else done at the same time?

I had no idea the MBC was pulling in air, so by tapping into the LICP instead of the BOV line it will stop this?

Only applies to bleeder type mbc as the ball in a ball/spring type should block the air passage preventing air being sucked in through the wastegate pressure relief hole unless it's a poorly designed ball/spring where the diameter of the ball is smaller than the air path inside the mbc housing allowing air to flow around the ball. Changing pressure source to the compressor/licp will prevent this because it's not a part of the vacuum, the BOV line is.

You HAVE to use the intake manifold is you want proper boost control. Why is that? The manual boost controller regulates the amount the wastegate is open based on the pressure at its source. Since you want to control manifold pressure, you want the MBC and the WGA to be recieving pressure directly from there.

Using a source off the turbo or intercooler pipe can cause you to have boost that changes with weather, load, and engine speed, and can also slow down boost response. By comparison, a manifold source will be fairly steady, solid, and reliable.

Like I have already mentioned above, the boost gauge is tapped to the manifold either way so you will be controlling manifold pressure either way. Remember, tech guide was written by people so it could be wrong and I respectfully disagree with it in this case. Do a simple search on boost spike and you will find countless examples of boost spikes being solved by just switching back to the compressor side. Will it work everytime, no. Like I already mentioned, this is just one of the possible causes of boost spikes.

Here's one example. http://www.dsmtuners.com/forums/showthread.php?t=198388

 

[DiamondStarM]

I havent done a boost leak test since the install and it was the only mod done at the time. I definetly need to look into that before I start making assumptions, but it does seem that using the licp or compressor housing as a boost source can only provide benefits. I dont see why the bov line has become the norm but I think Ill change mine even if its not the cause. Thanks for the help.

 

[oldman]

You're welcome. This is the third time someone pulled that tech article on me, I'm glad this one stayed nice and civil.

 

[tsunari]

Not to raise the semi-dead . . . but by relocating my boost source back to the compressor housing, my boost spikes were significantly reduced.

Now perhaps this is because the line is MUCH shorter and the response-time is better, who knows . . . but the simple before/after results in my case are clear- Instead of getting huge spikes, I now see the boost peak @ almost 17psi, then level off @ 15.5 and hold steady.

 

[bartels903]

I installed my MBC a couple days ago, I know for a fact I installed it correctly. But I turned it to its lowest setting before the bolt falls out, and I'm hitting 19 psi and what seems to be fuel cut (a sputter feeling and the car slows down a lot). Now before anyone tells me to do a boost leak, I am going to buy the parts tommorow to create and check. I just want to know some other options on what I should look for?

 

[oldman]

What brand/model/type of MBC and how is it setup?

BTW You need an AFPR for the rewired 255.

 

[bartels903]

What brand/model/type of MBC and how is it setup?

BTW You need an AFPR for the rewired 255.

Ah, Oldman, how did I know you would be first?

Its a offbrand model, bought it off the classifieds, it is a ball and spring. I think I used a diagram from you to set it up, I did not Tee it off the BOV, I went from the WG and..... what's the other line called?(sorry I have been working all day and am very tired)

I'm working on the AFPR, a certain brand you recomend?

 

[oldman]

Its a offbrand model, bought it off the classifieds, it is a ball and spring. I think I used a diagram from you to set it up, I did not Tee it off the BOV, I went from the WG and..... what's the other line called?(sorry I have been working all day and am very tired)

J-pipe (turbo outlet) fitting to mbc fitting inline but opposite to the adjustment knob, tee fitting on the mbc to the wastegate actuator, is that how you have it? If so, test run with the mbc bypassed by running a hose directly from j-pipe to actuator and post back results.

I'm working on the AFPR, a certain brand you recomend?

Aeromotive.

 

[GSTinBR]

I just installed my MBC and it appears that it is not regulating the boost at all despite the fact that I have it unscrewed almost all the way. The details are as follows:


I ran a vacume line from the compressor housting to the bottom part of the MBC (part opposite the screw). Then I ran a line from the outlet to the wastegate actuator.

The MBC is mounted laying on its side on top of the fans. Would the fact that it is on its side make a difference? I wouldn't think so.

I noticed two things. When I have it almost completely unscrewed I can blow air through it for a second and then it blocks it. It's like the ball is moving past the outlet hole but then coming back.

Secondly, on other MBCs that I have seen there is a small hole on the side. Mine does not have this.

I suspect that I have a bad MBC but I was hoping you folks might have some other suggestions to try. I don't have a boost leak tester but I will try to make one tomorrow if I don't get this resolved tonight.

 

[oldman]

Which brand/model/type of mbc? Are you sure it's not a bleeder type?

 

[GSTinBR]

It's a ball and spring type. I actually figured out the problem late last night. I had the screw too loose. I noticed that I could hear the ball rattling around inside. I tightened it up so it would fit more snugly and that seemed to solve the problem.

Thanks for the help anyways.