cant run over 14 psi or adjust psi

[allrice4g63]

Ok heres my problem i have a 98 talon tsi with a 14b swap. When i have everything hooked up like stock i run 8 psi. when i hook my mbc my friends mbc and his friends mbc i can not adjust the pressure at all it just spools to 14psi no higher no lower. i have boost leaked test a number of times and there is no boost leaks. I checked the wastegate with a pressure source the wastegate opens fine the turbo spools to 14 quick but doesnt seem to have full power until about 4-5k. even if i leave the vaccum lines to the wastegate it runs 14psi if i pinch them off or block them i run 14psi would anybody beable to tell me why it is doing this thanks.

 

[allrice4g63]

i have it setup just like in the pic that grnchevyz posted in post number 19 i have hooked up mbc many of times so i dont think that the mbc is my problem thats why i posted on here. could anything else be causing me to only run 14 psi besides a stuck open wastegate flapper and the mbc cause i know the wastegate flapper is working and is not stuck open i checked and rechecked that and my mbc is hooked up correctly is there anything else that could cause this. Possible boost leak that i missed cause this???????

 

[allrice4g63]

ok so tnight after work i ran a piece of pipe straight from the jpipe to the throttle body and i get mad boost numbers so im thinking boost leak can anyone back me up on this...

 

[grnchevyz]

Now that really sounds like a leak at the BoV.

1. j-Pipe -> WG = 12psi
2. no vaccuum source = 14psi not overboosting
3. j-pipe -> TB = overboosting

I would think that at 14psi'ish your BoV leaks like mad. Try to get 18psi from the first pipe off of the TB elbow and see if it holds. if it does, try it again after the BoV and see what happens. If it holds it again, try just before the IC on the turbo side...you could have a clog (although unlikely) or leak in the IC as well.

 

[GloriousDSM]

Do you still have your stock selenoid connected?

That would explain why when the mbc is unhooked you are still getting pressure of 14 psi or ie stock for a 2g

 

[allrice4g63]

No the stock selonoid is not conneted, i did another boost leak test and it sounds like it is coming out of the throttle body but i just replaced all the gaskets it sound like where the rod goes from the throttle body where the cable hooks up to the butterfly, but at 15psi on a boost test it is barely barely leaking outa there and the bov isnt leaking at all. But it has to be leaking somewhere ### when i run straight from jpipe to throttle body i got 20psi in like a second SCARY SCARY!!!!!!!!!!! I do have a 1g bov but i dont have the adapter kit is there anyway you can make the 1g bov work without the adapter or do you know how to make an adapter

 

[grnchevyz]

the answer to your issue is the stock 2g BoV, it can't hold much more than stock pressure,so around 13-14psi (1bar). Change it.

Hope that solves your issue.

 

[allrice4g63]

Hey man i appreciate all the help and you were right the stock 2g bov was the problem but not because it can handle over 14 psi the it was leaking all the time ### i took it off and blocked off the hole and DAY TO NIGHT differnce i have a 1g bov i just have to get a flange or make one

 

[JMiller]

Glad to see your problem has been resolved, but you might want to check your turbo for shaft play. Just saying that because from the stuff I've read (running pipe TB-Turbo, blocking off the BOV, etc.) you've done quite a few things that can break a turbo.