2G Tial MVS not holding boost ??

[starscreem]

hello
ok so my problem is i just had a 02 housing made for my tial mvs waste gate and that all seems to work fine but the problem i am running in to is, it seems my waste gate is leaking from a really weird spot and not holding boost right. so i put a 1 bar spring in it so i could have 14.5 psi, well it boosts to 17.3 on my true boost not so bad. well after driving around a little more i notice that my waste gate is starting to open around 8-9 psi ( im external dump so very easy to hear ) so i pin it and it holds all the way to 17.3 again. so i try to raise boost slow this time and it starts to open at 8-9 psi again. i go home pull the mvs off and change the spring to a 20psi set up. well same thing is going on, witch im stumped. i go do a boost leak test and i find that my waste gate is hissing like crazy at 10psi i spray it down with soapy water and low and behold its leaking right under the black hat in between the little metal flat piece and the lower black bottom of the hat right around the valve guide any one else had this issue?

i really am stumped and i also have my boost lines ran according to the aem set up for external waste gate. when i put it just boost source to lower in put in the mvs same problem is going on so i no its not my true boost.

am i thinking wrong on this but shouldn't the waste gate hold tell the spring pressure is meet and not open any time before?

well i had a talk with extremepsi and found out that it is supposed to leak pressure off from there so i guess that's fine.

so what would cause my waste gate to open at partial throttle around 10psi but if i go wot from there it will hold almost 22psi(i put a 20 psi spring set in the mvs). and i do have my lines ran according to what aem says for external gate. i tried this in all gears but 5th and it opens up in any gear starting at 10psi at partial throttle. any one herd of this or had this problem.

here is a few pics of how i have it hooked now.

 

[starscreem]

well today i removed the lines to my true boost and just ran the line from my boost source to the bottom port on the mvs and left the top open. same thing is happening its oping at 10psi at part throttle but if i got wot it will hold to 22psi(i put a 20-psi spring in.)could having to small of a boost source nipple cause this to happen? please some one help me i really need to get this in order so i can get a tune in my car!

i will say the nipples on the waste gate are a lot bigger then the one on my boost source

 

[agentorange313]

have you tried this method of hooking up the solenoid?

 

[starscreem]

please don't flame me on this but wouldn't that have nothing to do with the issue since the wast gate is opining before the spring pressure is meet. i have tryed the true boost way and even just boost source to waste gate same thing is happening. maybe ill try to plug the boost source port completely and run nothing to the gate and see if it opens or stays closed. yes i know i will have to be careful cause if it works right i could boost to the moon and kill my motor!!! im so stumped on this

 

[LiquidX]

Well you said it's leaking right? A bad diaphragm could cause those problems unless you are referring to it leaking exhaust?

 

[starscreem]

no i found out were it leaks is normal according to extrempsi that's how the pressure would bleed off they said i know the diaphragm is ok cause i have checked it 6 times in the last week. the spot it leaks from is the out side of the valve stem between the bottom plate and under the hat. or maybe they were wrong like i said im so stumped i guess i could make a video of this happening. like i said at part throttle letting the turbo build boost it will start to open around 10psi but if i was to floor it it holds to 22psi

also i know its not a bad or crushed spring like the other thread cause when i switched the 1 bar spring out for the 20psi one, it was just as hard to get off as it was to put on. if i would have not help it down parts would have flung all over my porch.

 

[LiquidX]

Try removing the TruBoost EBC out of the equation. Just hook a vacuum line from the turbo to the side port on the wastegate and let us know what happens then. Just make sure you can still monitor boost pressure with the gauge.

 

[starscreem]

i did that this morning and the same thing is going on. at this moment thats how it is set up the tru boost is just a boost gauge for me right now tell i get this figured out. i have the boost line coming from my lower ic pipe straight to the lower port of the wast gate and the top port open

here are to pics of how it is ran at the moment and it is opining at 10psi but under wot holds 22psi

 

[agentorange313]

After doing a lot of reading and researching, it sounds like a BOV problem.

Maybe you BOV is opening, or stuck open, under partial throttle allowing for pressure to escape and at WOT pressure forced the BOV to stay shut allowing for the full 20-22 psi.

Just a theory, I would check out your BOV. What spring are you running in the Tial BOV?

a diagram is you choose to start taking it apart: http://www.tialmedia.com/Exploded/Q and QR.jpg

 

[starscreem]

well when i did a boost leak test i had no issues with my bov. it is a older tial version not the new Q type, and to be honest i don't know what spring is in it i bought it from turbo-juice when he parted his car out and i know he had a bigger turbo then my s256. i never took it apart just bolted it on and never had a issue with it.

 

[daren_p]

no i found out were it leaks is normal according to extrempsi that's how the pressure would bleed off they said i know the diaphragm is ok cause i have checked it 6 times in the last week. the spot it leaks from is the out side of the valve stem between the bottom plate and under the hat. or maybe they were wrong like i said im so stumped i guess i could make a video of this happening. like i said at part throttle letting the turbo build boost it will start to open around 10psi but if i was to floor it it holds to 22psi

This doesn't seem correct to me. From what I can tell from your description, its leaking air externally? And its leaking where the bottom hat connects to the lower body? If this is the case, no, don't think thats normal. I've never heard mine leak externally doing a BLT & it doesn't make sense for it to bleed off there. Believe there should be an oring somewhere in the lower portion to seal things (but don't recall where it is exactly), maybe its damaged?