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Shift too fast and no boost? otherwise fine

Old Aug 8, 2003 | 09:41 AM
  #1  
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Shift too fast and no boost? otherwise fine

Some may recognize that Ive posted about solving boost issues and finding new ones. Well after swapping out Profec B control boxes with a friend. Im good.
But ever since I put in a short shifter and I shift fast its like it falls on its face to 2psi. But if I shift slower I works great. I had filters in the BOV and CRVs (little ones) and thought that might cause some problems so I removed them and its still the same.
Infact it sounds like rubber being sucked together if I shift fast. Im sure its a hose being sucked together but which one?
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Old Aug 8, 2003 | 12:18 PM
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I've heard the intake according hoses can collapse...those would be my guess because thats really the only place where its suctioning.'

someone had a similar problem with old intake hoses collapsing, i think batman...but not sure
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Old Aug 8, 2003 | 12:38 PM
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check y-pipe vac lines (under the vacuum/pressure tank in front of the UIM too)
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Old Aug 8, 2003 | 01:48 PM
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check your vac. lines on the solenoids that control the twin turbo, y pipe,pre spool
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Old Aug 8, 2003 | 02:38 PM
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lol what? that control twin turbo y pipe ???
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Old Aug 8, 2003 | 03:38 PM
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Eric, you are becoming the king of boost woes...I had a similar problem....Everytime I accelerated past 4500rpm in any gear and then upshifted I would have like 3psi...Turns out that one of the check valves below the pressure chamber was split...I replaced it and all is good...Start poking around checking your y-pipe coupler first then pull off the pressure chamber and check the little black and green valves, and also the green and white ones...Hope you get it fixed soon...I know boost problems are a major pain.
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Old Aug 8, 2003 | 04:04 PM
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haha,
yeah Dave I swear after this Ive had every boost issue known too man.
almost solved. Atleast now I can race, just have to shift slow
And I did suspect either Primary stock accordian hose, that I still have (2ndary hose is 3" pipe)
or BOV issue.
cuz Its a loud clogged noise when it does happen

Last edited by HeatTreated; Aug 8, 2003 at 04:11 PM.
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Old Aug 8, 2003 | 04:14 PM
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I had a similar problem and it was a sticking soleniod. If I shifted fast mainly into 2nd gear no or hardly any boost
but if I did it slower it would be ok.
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Old Aug 11, 2003 | 03:30 PM
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*update*
Put on the Apexi Intakes and that didint change anything.
I probed and didnt see any loose hoses.
Ill check somemore (under the UIM)
It really sux to finally have a great boost pattern that I can control and then not be able to race some punk *****, because I have to pause 2 seconds between shifts.
Ill find it soon enough.
Thanks for the tips guys.
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Old Aug 13, 2003 | 01:02 PM
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Man, I just dont see what could be causing this.
When I let off the gas after I see it only boosting 2-3psi. it makes a crazy loud suction noise.
Any more items to check.. I checked about everyhose.
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Old Aug 13, 2003 | 01:17 PM
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had same problem,took to dealer like i was rich,163.00 and a check valve that came apart in the seam of valve(old age) back to full power after quick shift at high rpms
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Old Aug 13, 2003 | 01:25 PM
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Originally posted by jefjarski
had same problem,took to dealer like i was rich,163.00 and a check valve that came apart in the seam of valve(old age) back to full power after quick shift at high rpms
This is exactly what mine was...it's like the previous owner tried to glue it back together with some yellow stuff.... BTW kefkarski, don't take your car to the dealer if you can avoid it...those dealer mechs are bofoons...You are close to Pettit so take you car there.

Eric...I usually allot a certain amount of time on certain problems after owning the car for close to 2 years. If I don't get it, I take it to a pro and spend the few extra bucks for piece of mind, and a lot more time and my hands for other things...Your's sounds like something extremely simple...you just need to have someone else dig around in there for you. It's like proof reading your papers in university...after you have read it about 10 times you will miss the same mistakes every time you read it...Then someone else comes along with a fresh head and fresh eyes and points it out in a few minutes...

Last edited by apneablue; Aug 13, 2003 at 01:50 PM.
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Old Aug 13, 2003 | 03:28 PM
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Talking

Originally posted by Rx-7$4$me
lol what? that control twin turbo y pipe ???
dude
there is a coma ,,,, after twin turbo and i am talking about the buterfly in the y pipe that is controlled by the solenoids
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Old Aug 13, 2003 | 04:27 PM
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From: OKC
yeah David,
I didnt see anything wrong with the check valves.
but I was wondering what happens when the Vacuum or Pressure chambers go out?
Ill double check the checkvalves. So your saying you heard that suction sound too with a bad check valve?
thanks brodas.
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Old Aug 14, 2003 | 06:08 AM
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If the vacuum or pressure chamber go out it will have the same effect on boost as if a check valve went out...If I remember right the vac and pressure chamber are in two pieces...a top and a bottom and they are held together by some gummy looking black stuff...This is something you may want to check also...With mine every time I got on it I heard a ptssssssssssssss or a wooooooooooooooshing....Maybe it was a pressure sound or a vac sound....to me it sounded like a pressure sound though.
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Old Sep 19, 2003 | 03:14 PM
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Lightbulb

Well I glad to see I'm not the only "7" fan that is going crazy...everytime I try to explain this to someone, they look at me and give me that "are you stupid?" look. I've already done the hose job and replaced two main solenoids and even though I'm getting better response and not to mention, it looks GREAT!!! I will go back through it and replace the check valves just in case. Thanks for the suggestions...
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Old Sep 19, 2003 | 04:23 PM
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Yeah, sometimes its tough to get good answers. But there are those who help tremendously.
the check valves are easy to check.. I have extras if you need some.

My problem was with the Turbo Control (Solenoid &/or Actuator). Hopefully its not yours. cuz I went Non Seq and never looked back.
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Old Sep 24, 2003 | 10:25 AM
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What type of single did you go with?
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Old Sep 24, 2003 | 10:42 AM
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Originally posted by kempo
dude
there is a coma ,,,, after twin turbo and i am talking about the buterfly in the y pipe that is controlled by the solenoids
charge control actuator
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