Video, Possible bad wastegate on brand new MHI Evo3 16G? Boost is uncontrollable. Hlp

[95EclipseGST]

I just got a brand new Evo3 16g installed along with a new 1g complete engine. I went for a drive for the first time and i can barely put my foot on tha gas and drive the car beacuse the boost is totally out of control. YouTube - Uncontrollable boost on "new" MHI Evo 3, 16g Turbo Help
The rpms are really low and this boost just wants to shoot to the moon. This Turbo is brand new ! Help me please, to get this fixed in the next week or so. I pulled on the wastegate rod and i can pull it back, but its not easy to pull it back. Its not binding though and is a smooth pullback. In this video, my boost shot to 20 psi. Did i hurt the engine by doing this? The car seems ok, but i need to know if i "possibly" damaged something and dont know about it yet. What "could" happen with this spiking to 20 psi like this?
What parts need to be removed to even get to removing this wastegate.
What do i do once it is removed? I cannot understadn how im having trouble with a brand new turbo. Could it be "anything" else? BOV? Anything? I really dont want to take this to someone else and have them blow my engine by trying to figure out the problem. Can you please try to answer all the questions asked in here? Thank you, i need help with this bad ! Please

 

[big_d]

Do you understand how a wastegate or a mbc works 95EclipseGST?
You had a pressure source, the intake manifold. You attached that vacuum line to the wastegate. Since a 16g wastegate is manufactured to open around 10lbs, it happened. You attached the mbc (not in the best manner but ok) and you gained 10lbs of boost. Unscrew the mbc until you can blow through it without an restriction and reinstall. It should still be at 10lbs. Everyone is telling you to relocate your boost reference closer to the compressor cover because that will minimize the response time of the wastegate opening. After doing so you can slowly begin increasing boost by turning the mbc clockwise until your desired level is reached.

 

[skatershawn]

the waste gate is held closed with a spring, and when MHI engineered the turbo they wanted (for i don't know what reason) it set roughly at 10psi... the pressure of the intake is hooked to the wastegate aculator and in there where the spring, when the pressure gets high enought to push the piston and diapham in there it opens the actually wastegate flapper that the arm is connected to!!

The spring is what holds it closed and when the pressure in the intake is below the amount needed to push the force of the spring it would open! Its not a set amount cause all cars are different, like mine peaks at 6psi when hooked straight to the waste gate!!

Now when you put a MBC in the mix... it restricts the pressure going from the intake to the wastegate causing it to stay closed intell the pressure in the intake is enough to bypass the spring in the MBC and get to the wastegate!!

It Stays at 10psi because thats what its set at... the degree of how much the flapper is open and how much exhaust is getting bypassed by the turbine!

i hope this helps you understand more!



ilco187...
I understand where you are coming from, i personally am not disagreeing with you!
its just, if you look at his picture he has the bov on the same vacuume hose!!
its best to just have one solid vacuume line going from the souce of intake pressure, where ever that may be.. to the wastegate! to get a more accuate tune!
IMO :/

 

[crash89]

Do you have a nipple on the turbo (or j pipe) TO the wastegate. I was having a similar problem, troubleshot to that. I didnt have a boost line to the wastegate. Got a line from the turbo to the wastegate and boosted 12psi strong. Hope this helps

 

[toofast82]

"toofast82: If you don't run vacuum to the wastegate, it will not see pressure. That will cause it NOT to open at all. DO NOT do this."

^ Then someone explain why i was getting 10 lbs of boost by running vac straight to the wastegate? It opened if i got 10 lbs of boost right? toofast?

You said you were going to put a vacuum cap on the wastegate nipple, that would cause it not to open.

If you're running a vacuum line straight to gate and its holding 10psi, then that means its working as it should. Now get your mbc hooked up right and adjusted to your desired boost level.

 

[green92gsx]

i NEVER hook my mbc to the j pipe nipple, the best way to actually make sure you are keeping the correct boost pressure is to tap off the intake manifold, you will want to make sure you are keeping the manifold pressure at what psi you want, not your piping, but do as you do i guess.

I do the same because of the pressure drop from the intercooler and piping. If I dial in 40 psi,I know it's 40psi at the manifold not the compresser cover.

 

[JusMX141]

I do the same because of the pressure drop from the intercooler and piping. If I dial in 40 psi,I know it's 40psi at the manifold not the compresser cover.

Isn't the manifold pressure going to be the same regardless of where the MBC is tapped?

If you're dialing your boost level at the manifold by what the gauge is reading at the manifold, it doesn't matter if the turbo is generating 40.1psi or 52psi....you're tuning the MBC based on what boost level you're seeing at the manifold.

 

[GooeyGus]

bottom line:

You hooked directly from your manifold to the wastegate. You saw 10psi. Your WGA is working correctly.

Now, install your MBC. Unscrew it as far as it will go. You should still see 10psi.

Now slowly begin to turn the MBC screw in, using very small increments. Your boost should slowly rise with each adjustment.

 

[95EclipseGST]

I ran the MBC in between the intake manifold vacuum and the wastegate nipple and i have controlled boost now. I wonder why it wasnt giving me control when tee'd off at the BOV? I had it all set up the same basically, just took the BOV out of the picture. So is this method way ok, without drilling into my j-pipe? Also this is a brand new engine, did i hurt anything by boosting about 5 times WOT? Im backing off now and going to baby the car. Was that extremely harmful to boost with a brand new engine?

 

[97gst_spyder]

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.

It does not matter which one. Your boost gauge is hooked up to the IM last I checked. So you tune your mbc to what you wanna see on the boost gauge correct? If so you sir just tuned the psi to what you wanna see in the IM...

 

[95EclipseGST]

Thank you for the info guys. That will be my new way of doing the MBC connection. I will leave it like that.
My BOV used to be a lot louder, but its not loud at all now "its 10 years old" I heard it flutter a few time..."not sure why" I am starting to think a need a new BOV now, but how do you tell if it needs to be replaced. If your turbo works and it seems to be blowing off, just not as loud, could it be causing backspin or anything like that and me not know it? I need to test my BOV somehow. If i remember right. i put compressed air into the nipple before and i couldnt get it to open.

 

[tsi1991awd]

Isn't the manifold pressure going to be the same regardless of where the MBC is tapped?

If you're dialing your boost level at the manifold by what the gauge is reading at the manifold, it doesn't matter if the turbo is generating 40.1psi or 52psi....you're tuning the MBC based on what boost level you're seeing at the manifold.

Couldn't have said it better myself. The boost gauge is supposed to be run off of the intake manifold, that will give a correct reading for the pressure at the manifold.

You run the MBC off of the j-pipe (or turbo) straight to the wastegate. You adjust accordingly and that sets the pressure for what you see at the manifold. It doesn't matter if your line is coming off the IM or j-pipe...you get the same result. I would rather run a SHORTER LENGTH of vac hose and get the most accurate results