nightram
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Boost boost and overboost!
Got my car back form the mechanic and it is doing the most perculiar thing.
With the throttle put down it climbs past 16PSI to somewhere past 20 (blew hose off) if im not paying attention. This is annoying as I am not able to "floor it" for fear of destroying my car. I have the Tvsv disconnected. My AEM boost controller is in "off mode" and yet the boost is not being properly governed by what I imagine is the 10 PSI waste gate spring.
My next step is to remove the Boost controller solenoid totally to verify if it is or isnt working. Am I missing anything?
1989 MR2 GT (SW20) 325hp, sold to buy a Jeep I guess "you wouldn't understand"
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purple5ive
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Re:Boost boost and overboost!
2012/04/27 19:01:07
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WHAT did you get done to the car, was it anythign with the dump pipe/turbo??
im guessing the wastegate flapper has jammed shut in the closed position allowing the turbo to overboost., sometimes the actuator arm itself can get stuck where it joins the flapper, be carefull not to overboost and cook your engine. its good fun to ahve that much boost but the concequences later on arent that good.
cheers
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nightram
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Re:Boost boost and overboost!
2012/04/27 22:37:57
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This last time, nothing but a gearbox change.
I was thinking it might be mechanical too. Ill give the arm a jiggle...
1989 MR2 GT (SW20) 325hp, sold to buy a Jeep I guess "you wouldn't understand"
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blacky83
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Re:Boost boost and overboost!
2012/04/27 22:50:36
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Hook up compressed air to the wastegate diaphram and see whether the actuator is moving. Then hook it before your controller to see whether thats operating properly.
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nightram
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Re:Boost boost and overboost!
2012/04/29 20:31:43
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Would a Cho-cho-cho from the turbo on a 2 PSI deceleration indicate the diaphragm working?
1989 MR2 GT (SW20) 325hp, sold to buy a Jeep I guess "you wouldn't understand"
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nightram
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Re:Boost boost and overboost!
2012/05/02 19:03:21
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OK, so I have found out why I have been overboosting. Here is the Pic. Can you see what is wrong? (ignore the disconnect)  Answer (in white) -> The waste gate valve was open when the dump pipe was fitted jamming it 80 deg more than it should be[<font]<-
1989 MR2 GT (SW20) 325hp, sold to buy a Jeep I guess "you wouldn't understand"
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purple5ive
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Re:Boost boost and overboost!
2012/05/03 09:53:53
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Figured it would be the waste gate. Good you found it spoon and sorted it out.
Cheers
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MRTurbo
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Re:Boost boost and overboost!
2012/05/03 10:01:34
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how was it open when the dump was fitted?
mine sticks open sometimes due to the dp flange (F&%&^# BERK!) but obviously doesn't cause overboosting rather underboosting lol
pulling it off this weekend and attacking it with a dremel.
1990 SW20 GT 3S-GTE Targa 2001 Honda CBR600F4i 
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purple5ive
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Re:Boost boost and overboost!
2012/05/03 12:55:11
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Would have been jammed close not open.
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nightram
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Re:Boost boost and overboost!
2012/05/03 13:17:21
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Was jammed open. It got caught on a incorrect fitting gasket.
1989 MR2 GT (SW20) 325hp, sold to buy a Jeep I guess "you wouldn't understand"
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purple5ive
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Re:Boost boost and overboost!
2012/05/03 21:37:52
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if the wastegate flap was jammed open it will boost really late not overboost.
unless i have misunderstood what your saying ...
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MRTurbo
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Re:Boost boost and overboost!
2012/05/04 10:06:57
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I think he means it was jammed half open/half closed so it'd still boost up, but wouldn't open enough and that caused chronic boost creep.
1990 SW20 GT 3S-GTE Targa 2001 Honda CBR600F4i
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purple5ive
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Re:Boost boost and overboost!
2012/05/04 11:22:44
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yep got it, i was thinkign that but was wonderign how it got jammed in the halfway mark lol.
anyways its all sorted now im guessing.
mine has done this once but only after an extended period of driving on the freeway (about 2 hours or so) and then when i booted it, it got stuck in the open position, im guessing the heat from driving continuosly expanded the flapper just enough to get it jammed, its never happened before and after again, fixed it by doing some full throttle pulls in 4th gear.
cheers
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