Wastegate Problem 16g

[JayB12]

Had this issue before, thought I resolved it, but it happened again. I have a 16g, slowboy mbc that's T'd into the bov line, set to 14 psi. I overboosted before, did all the steps to check the wastegate, and it opened. I stuck my mbc line back on the nipple, ran fine.

Today, I've been having a leaning out problem so for now I decided to take off the mbc line and run it open. I did a pull to see the results (I assumed it would open ~12psi)...if I kept going I could have easily maxed the gauge. Just to test, I stuck my line back on and the wastegate opens at 14psi like normal. Maybe the first time I overboosted the line had come off a little causing it?

What would cause this?

 

[JusMX141]

Let me get this straight- you removed the pressure source from the actuator, did a pull, then wondered why the boost pressure maxed out with nothing in place to open the actuator?

 

[JayB12]

I thought that that's how you ran it off wastegate spring pressure?

 

[Redwidow]

And your have your source for the wastegate teed into the blow off valve line? Big no-no

You need a vacuum source directly from the intake to open the wastegate. You need to run a line from your intake manifold strait to the wastegate with no interruptions. Then the wastegate will open at the spring pressure.

 

[JayB12]

And your have your source for the wastegate teed into the blow off valve line? Big no-no

It's never caused a problem and it's been like that a soild 60k+

I would like to take the turbo off and add a boost source to the comp. cover though.

 

[JayB12]

You need a vacuum source directly from the intake to open the wastegate. You need to run a line from your intake manifold strait to the wastegate with no interruptions. Then the wastegate will open at the spring pressure.

Ok. That clears things up. I didn't know that.

Another stupid question, Which direction do you turn the knob on the mbc to turn it down and how much do you turn it for 1psi or 2 ect

 

[JusMX141]

I thought that that's how you ran it off wastegate spring pressure?

Incorrect. You have no boost source, so there is no air pressure in the diaphragm to open the wastegate. Doing this will cause the turbo to make as much boost as it possibly can.

You need a vacuum source directly from the intake to open the wastegate.

Actually, I have a SBR MBC at the shop and it appears to be the same as any other knockoff bleeder-style controller...meaning you can source it directly to the compressor cover with no regard to a vacuum source.

But you definitely don't want to tee bleeder-style MBC's into the BOV line. The BOV will hurt the MBC's performance by slowing down it's response causing boost spikes/drops, and the MBC's bleeder will hurt the BOV's performance by essentially causing a vacuum leak causing compressor surge.

 

[Redwidow]

Actually, I have a SBR MBC at the shop and it appears to be the same as any other knockoff bleeder-style controller...meaning you can source it directly to the compressor cover with no regard to a vacuum source.

I didn't not know that on the sbr mbc. Thanks for that info justin

 

[JayB12]

So realistically the only way I can "properly" do this it to have something like the IC pipe, comp cover, or IM taken off and a bung welded onto it?

 

[Dylan0123]

It's never caused a problem and it's been like that a soild 60k+

I would like to take the turbo off and add a boost source to the comp. cover though.

Proper way to set up a ball and spring type mbc:

http://www.dsmtuners.com/forums/articles-turbo-system-intercooler/237982-best-way-install-mbc.html

http://www.dsmtuners.com/forums/art...255354-another-proper-mbc-hookup-diagram.html

 

[Redwidow]

So realistically the only way I can "properly" do this it to have something like the IC pipe, comp cover, or IM taken off and a bung welded onto it?

If you don't have an unused nipple on any of those then id say yes, that's the only way