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very bad over boosting!

97GSTJake

Proven Member
64
0
Mar 3, 2006
North Vernon, Indiana
Ok i had my uicp, hard intake, and joe b manual boost controller put on back in may or so... the first few nights the car ran great and felt a gain from the mbc (set at 14 psi, but still overboosted every once in a while)... about 2 weeks later i ran a boost leak test on it and it was leaking a lot of boost from the blow off valve flange (no gasket on it, just RV silicone high heat, so i re did the flange with rv silicone gasket maker, and it has still overboosted very badly.... I have turned the boost controller to the very lowest amount possible on it and bought gasket material and made my own gasket. The car is a little better but when i get on it i still here the extremely loud SHHHHHHHHH, and the boost controller shows almost 20 psi within seconds and the car feels very overpowered driving, so i just let off and shift. My question is why is the overboosting so bad still? I have put a real gasket on it and my boost controller is turned to the VERY lowest possibe position it will go.... where should the mbc be shown at on psi if turned to the very lowest position possible? shouldnt i be able to just turn the boost completely off..... i just want the boost back to stock psi levels... so how do i do that? just remove the mbc and hook back up the stock boost solenoid and all wiring?
 

No_Skillz

Proven Member
2,758
25
Dec 8, 2004
Freehold/Morris, New_Jersey
What is overboosting, exactly? Spiking? Creeping? If you're still on the stock t-25, it sounds to me like you have your MBC set up wrong and the turbo is unrestricted, spinning itself as fast as it's little compressor wheel can go.

What is this "lowest setting" that you have your MBC set at? The lowest setting is the knob all the way out. That is stock boost level, and it's as low as you can go. Furthermore, having your knob all the way in will also cause the symptoms you explained.
 

97GSTJake

Proven Member
64
0
Mar 3, 2006
North Vernon, Indiana
ok well one of my buddies set up the MBC (which is set all the way out).... the mbc could never really be set properly it seemed.... it always just creeped wherever i set it anyway.... even with the mbc set all the way out it is creeping up to almost 20 psi with the pedal 3/4 way down..... and i do have the stock turbo on.... and i have a greddy type s and uicp installed the exact same time everything else was done..... could it be the gasket still ? i run boost leaks and it is all around the bov flange leaking air...
 

No_Skillz

Proven Member
2,758
25
Dec 8, 2004
Freehold/Morris, New_Jersey
Having a boost leak will only decrease the amount that you're boosting, not increase it. There is something wrong with your MBC, or you didn't install it correctly. Make sure your friend didn't switch the vacuum hoses by mistake. You can also try attaching a vac hose directly from the compressor cover to the wastegate, which will make you run stock boost.
 

97GSTJake

Proven Member
64
0
Mar 3, 2006
North Vernon, Indiana
ok so today we tested the car and i have no visible leaks... we took my mbc off and reconnected the stock solenoid and everything back to normal..... the car is still acting up so i believe it may be the wastegate actuator acting up....do think this could be the solution to my problem? I hit 25 psi (its not the boost gauge) on stock boost solenoid and all..... i wish i could figure this shit out
 

cumpersgsx

15+ Year Contributor
427
1
Jul 25, 2005
Detroit, Michigan
This exact same thing happend to me...i almost blew the turbo...when i took it off i had soo much shaft play. So i just upgraded to a 16g. But i couldnt get the boost down to what i wanted it at either.
 

chuckg

Proven Member
69
0
Dec 7, 2005
Springfield, Missouri
This happend to me once too, but it just ended up being a kink in my vac line. Id check for simple stuff like that first before I went after the wga.
 

97GSTJake

Proven Member
64
0
Mar 3, 2006
North Vernon, Indiana
i have checked all the lines in they were great yesterday but ill give it a second look....... my check engine light came on after we installed all my shit, autozone checked it out as just the mas sensor having malfunctioning.... but you think i could have a retarded mas sensor?
 

97GSTJake

Proven Member
64
0
Mar 3, 2006
North Vernon, Indiana
would my over boosting have anything to do with the fact of tuning my blow off valve...becuase i have the greddy type s, which is tunable on the top....... would tuning it wrong give me this outcome?
 

97GSTJake

Proven Member
64
0
Mar 3, 2006
North Vernon, Indiana
i dont have the tools to test it with (bicycle pump, something to fit the input) or i would.... im just getting a new actuator and seeing what happens
 

98gst14b

Proven Member
453
0
Jan 24, 2006
Keys, Florida
Just take a vacuum line striaght from your acutator and just suck or blow on it, you will tell if there is a leak in the acutator, it should be completly airtight. Also on the MBC, was it a ebay mbc the ones for $10? If so you have to cut the spring it is too long and has too much force even on the lowest setting, try cutting a couple links of the spring and see if that does anything, if it dosent you woint hurt anything, the knob will just have to be screwed in a little more. Good luck
 

97GSTJake

Proven Member
64
0
Mar 3, 2006
North Vernon, Indiana
ok well, i bought the faze boost vac gauge from advance auto parts for $50..... and i took the line off the wastegate actuator and blew air into it and i can hear air coming out of the actuator but i couldnt tell where exactly it came from.... so what do you think?
 

97GSTJake

Proven Member
64
0
Mar 3, 2006
North Vernon, Indiana
i just hooked a bike pump onto the line to the actuator and the actuator itself is losing air pretty heavily......
 

No_Skillz

Proven Member
2,758
25
Dec 8, 2004
Freehold/Morris, New_Jersey
Losing air wouldn't cause uncontrollably high boost. Just the opposite. Forget about that, lets go back to your MBC. Remove it, attach a hose straight from the compressor cover to the wastegate. If this works, your MBC is bad. You can cut links off of the spring if this is the case, but lets see first.
 

97GSTJake

Proven Member
64
0
Mar 3, 2006
North Vernon, Indiana
well, actually the mbc was removed a few days ago and all stock lines are hooked back up....... thanks for your posts by the way bro, i appreciate it...oh and just alittle piece of information when i was over boosting and all, I would get into about second gear and i would watch the gauge and give it a little gas, as i would watch the gauge it went up to 5 psi very slowly and then was just like a sling shot straight to around 20 some psi as i added gas.... it was not a steady gain like it should be....
 
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