Maybe be I am a idiot but i need help. First let me tell you what is on the car. Stock ported mani, 20glt turbo, SS O2 housing, Hallman MBC (stiff spring)

1. With positive pressure source going straight to the wastegate and no MBC. Boost will go to about 16-18psi then at about 5k rpm boost will rocket to 25psi.

2. With no pressure to the wastegate just running straight wastegate, boost will go right to 22psi and hold steady.

3. Put back MBC into play and adjust it boost will got right to 24-25psi and hold steady.

4. Turn the MBC all the way down and boost will do the same as in 1.

Now correct me if i am wrong but as a i did in #2 shouldnt i run alot more than 22psi. Also I feel as if 25psi is all the boost i can run. This happened on the stock wastegate and I thought it was broken so i just bought and installed the new FOrge wastegate and it is doing the exact same thing. The only thing that i can think is happening is that i am overrunning the stock wastegate hole in the hotside. Some help will be greatly appreciated on this as to I am stumped and getting very frustrated. Though 24-25psi of boost feels good I would like to have some control of it and run more or less if i wanted to. Thanks in advance.

PS. I have the MBC tapped into the BOV line because my turbo outlet pipe has no nipple and none of the vaccumm lines have splits.

 

Let's see if I understand. You are running the Forge WGA for the IX on your new 20G-LT. Is that right? Did you install the WGA yourself? Off the cuff, I am thinking that maybe the preload is to high on the WG.

 

Well it did it on the stock actuator also no matter what the preload ie loose or all the way tight. Installed the forge tonight on a limb to see if that helped and it did nothing. I have gotten pretty good with the adjustment of the wastegate and right now the forge unit I only have a little preload on it because it has the 19psi spring

 

i believe your wastgate is not preloaded correctly, it needs to be adjusted, what you need to do with the car off, i take off the clip that holds the wastegate arm to the flapper arm and then adjust it so that the arm is completely closed and then go from there.

 

When i had the stock wastegate acutator on the turbo i tested it both very loose and all the way tight with the same results as listed before. Right now i have the forge wastegate arm adjusted so that i slightly have to pull it up to slide it on the flapper arm on the turbo. This wastegate also has the 19 psi spring. Does anyone here think that my exhaust gases are overflowing the wastegate hole?

 

Did you try disconnecting the actuator rod from the flapper valve arm and wiring the flapper valve fully open? If you were to do this and it still spikes high, then the cause of the problem is not related to the WG actuator, and you'd have to port the WG bypass port in the turbine housing.

 

look it is your wastegate, your flapper in your hotside isnt closed correctly, need to be completely closed during idle.

 

No i have not tried that yet. I will give it a shot tomorrow night when I get home from work. What kind of boost do you think i should see with it wired open?

 

It is complety closed at idle and it has some tension on the wastegate arm keeping it closed also.

 

You say that you have to slightly pull it up to slide it on. To arrive at base WG pressure you should be able to slide the turnbuckle on and off the flapper valve arm w/o having to exert any axial pulling on the actuator rod whatsoever. It has to slide off and on freely. Otherwise you may have too much preload on it and not realize it. So, start over and loosen the actuator rod completely.

 

Also what do you think makes me only run 22 psi when i have no connection to the wastegate at all? This has me boggled. But when i rehook up the MBC i can run 25psi.

 

The amount i slide it on to is so little that one half turn of the arm and it would slide freely on and off.

 

Yes, I understand, but try it anyway. Loosen it until it just slides on and off totally free. Then take it for a WOT run and note the boost level. This will absolutely and positively be your base WG pressure, which you need to know before proceeding any further. Sometimes a single turn or even a half turn can make enough difference to cause the scenario you are describing.

At least we'll establish your base WG pressure, which we need to know, and also be one step closer to figuring out the problem.

 

Should i do this with a direct pressure source hooked to the wastegate or with no pressure source to the wastegate. I will try this again but i am sure of the results of which i have had. It will go to like 16-18 psi and then at about 5k rpm rocket to 25psi.

 

Run a hose from the T in your BOV/intake manifold line to the nipple on top of your WG solenoid. Or if you have your MBC hooked up already just turn it out all the way to full soft. This last way you don't need to plumb directly off your boost reference source.

I had the same problem on my TME the other day and I had to loosen the actuator rod completely. The boost was just spiking to 22#, and I kept loosening and loosening the turnbuckle, until finally with the last 1/2 turn it came down to a base WG pressure of 17#. Thanks for humoring me. I hope we figure this out for you, so that you can enjoy your new turbo.