building only 4 to 5 psi......

[2DaTrakNow]

ive done a boost leak test, and i see no signs of any air leaking. When i first got the car (3 months ago) it had no boost controller or anything, and it would spike about 16 psi and then fall off to about 11-12. I then installed a MBC, and the spike went away, but i could only build about 10 psi. When i turned it up, nothing happened, and when i turned it down, nothing happened there either. I would hit about 10 psi, and stay there. So i thought maybe i installed it wrong, so i got on this site and found like 3 different ways to install it, so i tried every way, and nothing ever changed. Then it seemed like i was losing boost by the day. it went from 10, down to about 9, then 8, and now im only at about 4 to 5. But if i am at a lower rpm level and hit the gas, and build boost. I will "spike" up to about 9 then once my car actually gets going, the boost will come down. So if i go hard through 1st, 2nd, and 3rd i will be at about 4-5 the whole time. But if i am putting along, and punch it, it will go up to about 10, then drop off. Whats the deal? could my turbo be going bad? 80k

 

[project15]

did you play with the boost control solenoid at all? if that's unplugged you'll only get a few lbs of boost.

 

[No_Skillz]

What are these "signs" of boost leak that you looked for? Did you use soapy water? How is your mbc hooked up? Are you sure it's working? Is your wastegate flapper working? Also look for shaft play next time you do a boost leak check.

 

[talon1987]

Try checkin the operation of yur wastegate flapper ... possibly stuck open or opening to soon

-Fitz

 

[2DaTrakNow]

did you play with the boost control solenoid at all? if that's unplugged you'll only get a few lbs of boost.

I am pretty sure i never unplugged it, but i will double check just to be safe.

 

[2DaTrakNow]

What are these "signs" of boost leak that you looked for? Did you use soapy water? How is your mbc hooked up? Are you sure it's working? Is your wastegate flapper working? Also look for shaft play next time you do a boost leak check.

I used soapy water, and had my friend sitting in the car looking at the gauge. The MBC is no longer hooked up, i took it off when i realized i had a problem, and then put it back to how it was. How do i test the WG flapper? and for the shaft play, i can't move the shaft/wheel up or down hardly at all, but it slides back and forth just a very small amount. It does seem to spin really easy though, i just stuck my finger in and spun it. I dont know if that is normal or not, but it seemed to sping too easy, maybe as if it was loose or something?

 

[2DaTrakNow]

is it possible my turbo could be going bad?

 

[GVR4592]

How do you have your vacuum lines hooked up to your wastegate? If you run a direct source of vacuum/boost directly to the wastegate that will eliminate the MBC and the BCS.

If you still have the problem, look at your wastegate flapper and the wastegate actuator arm and make sure they are attached. The cotter pin gets brittle from heat and breaks. Then the arm comes off of the flapper and you get very little boost.

If that isn't the problem it could be a broken or cracked flapper, or cracks in the exhaust manifold or turbo. It could also be a large exhaust leak pre-turbo.

 

[2DaTrakNow]

How do you have your vacuum lines hooked up to your wastegate? If you run a direct source of vacuum/boost directly to the wastegate that will eliminate the MBC and the BCS.

If you still have the problem, look at your wastegate flapper and the wastegate actuator arm and make sure they are attached. The cotter pin gets brittle from heat and breaks. Then the arm comes off of the flapper and you get very little boost.

If that isn't the problem it could be a broken or cracked flapper, or cracks in the exhaust manifold or turbo. It could also be a large exhaust leak pre-turbo.

sorry, i didnt meant that i have a vacuum/boost line directly to the wastgate. I have the line that comes out of the turbo in a T, and one line goes to the WG and the other goes to the BCS. Thats how it was when i got it, so i am going to assume thats stock?

I dont think that it would be a pre-turbo leak, because i am not hearing any of the sounds i did when i had an exhaust gasket leak a while ago. But it is a possibility, so i will look into that.

The wastegate seems like a good idea, i will try to check the flapper and WGA arm, plus the cotterpin. If that isnt the case, i will just leave it for a week or two, because i am getting a bigger turbo and external wastegate soon. So i will look more into the problem when i replace it, just to see what it is, if i cant figure it out now.

 

[GVR4592]

I would eliminate the bcs. Just run the boost source directly to the wastegate. That will give you the wastegates default boost setting which is around 9-10 psi.

 

[Jhoe]

Not like I'd ever do this ::ahem:: but is your boost controller hooked up backwards? I only built a small amount of boost off of the launch and then dropped to 4-5psi during the run, still ran a 14.0 too .

 

[2DaTrakNow]

Not like I'd ever do this ::ahem:: but is your boost controller hooked up backwards? I only built a small amount of boost off of the launch and then dropped to 4-5psi during the run, still ran a 14.0 too .

No it isnt on backwards. I had in on the right way, and when it didnt work i thought maybe i had it on backwards, so i went ahead and changed it back and forth a few times, and then i looked up the right way, and it was correct.

 

[Jhoe]

It was mentioned to check your wastegate actuator, the cotter pin and also pressure check, have you had time to do that yet?
This also may help....
http://dsmtuners.com/forums/showthread.php?t=198327&highlight=taboo+speed+shop+emissions

 

[deletrius]

when my wastegate was malfunctioning it wouldnt hit boost until 4500 rpm, so it sounds to me like you have a boost leak.