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Big vacum leak!

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Old Nov 5, 2005 | 03:15 PM
  #1  
fire350tpi's Avatar
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From: Middleboro, MA
Car: 1988 Pontiac trans am/gta
Engine: 350
Transmission: 700r4
Axle/Gears: 3.23's
Big vacum leak!

i can hear the hiss when i touch the throttle from the drivers seat!


but i keep searching and searching cant find anything not disconnected and i was thinking it have to be pretty big to hear a hissing sound


i hear some people use sea foam or something to find a leak?


any info on that THANKS!
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Old Nov 5, 2005 | 03:23 PM
  #2  
Scheister's Avatar
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From: Ohio
Car: 85 IROC
Engine: 305 TPI
Transmission: 700R4
you can spray carb cleaner around the engine to find it. when the carb cleaner hits the area with the leak it will surge slightly
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Old Nov 5, 2005 | 03:36 PM
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fire350tpi's Avatar
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From: Middleboro, MA
Car: 1988 Pontiac trans am/gta
Engine: 350
Transmission: 700r4
Axle/Gears: 3.23's
hmm, yeah thats a good idea, i will give it a try, i just wish i could get i tinto a shop but its not registered yet so :/
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Old Nov 5, 2005 | 03:37 PM
  #4  
fire350tpi's Avatar
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From: Middleboro, MA
Car: 1988 Pontiac trans am/gta
Engine: 350
Transmission: 700r4
Axle/Gears: 3.23's
see thats another thing it wont start ( or keep running without my foot on the gas)

for a little bit once it warms up its fine, but the idle surges up and down, up and down
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Old Nov 7, 2005 | 09:25 PM
  #5  
mean57's Avatar
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From: plainfield, il
Car: 87 gta
Engine: L98
Transmission: 700r4
stik a dime in the trottle linkage betwwen adjustment screw and throttle body. should raise rpm's just enough to keep car running.

ps. don't forget to remove dime when done.
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Old Nov 8, 2005 | 05:38 AM
  #6  
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From: Middleboro, MA
Car: 1988 Pontiac trans am/gta
Engine: 350
Transmission: 700r4
Axle/Gears: 3.23's
alright, so u think i should put the dimmy there and spray around and if it surges thats where it is ?
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Old Nov 8, 2005 | 07:27 PM
  #7  
87TPI350KID's Avatar
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Car: 1987 IROC-Z Camaro
Engine: 5.7 350 TPI - SLP Runners, AFPR, MSD Goodies
Transmission: 700R4 - Shift Kit, Corvette Servo
Axle/Gears: BW 9 bolt, 3.27s
Check around the back of your plenum, theres quite a few vaccum lines there that like to wiggle loose. Also check your charcoal canister
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Old Nov 8, 2005 | 07:49 PM
  #8  
fire350tpi's Avatar
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From: Middleboro, MA
Car: 1988 Pontiac trans am/gta
Engine: 350
Transmission: 700r4
Axle/Gears: 3.23's
i took a look at the back of the plenum they seem all ok, there is one i dont know about thou its of the tb, goes into a t one part goes to the egr or somewhere back there, and the other has nothing in it, but its tiny i also noticed my carbon cannister vacuum hose is so dirty when i touch it my hands turn black and theres crackes and stuff in it
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Old Nov 8, 2005 | 10:56 PM
  #9  
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From: Jacksonville, Florida
Car: 1992 Camaro Z28
Engine: 5.7 LT1
Transmission: 4L60
Axle/Gears: 3.23's
That tiny tube your mentioning goes to a small port underneath the throttle body. That could very well be your vacuum leak. You also said that you have to keep your foot on the gas until its warmed up to keep it started, sounds like a bad IAC valve, its what controls the incoming air at idle.
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Old Nov 9, 2005 | 02:03 PM
  #10  
fire350tpi's Avatar
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From: Middleboro, MA
Car: 1988 Pontiac trans am/gta
Engine: 350
Transmission: 700r4
Axle/Gears: 3.23's
yeah i have it connected at the tb, but it goes into a T tube, one to tb, one to egr? and one that has nothing plugged in
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Old Nov 9, 2005 | 05:29 PM
  #11  
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From: Jacksonville, Florida
Car: 1992 Camaro Z28
Engine: 5.7 LT1
Transmission: 4L60
Axle/Gears: 3.23's
Can you take a picture of this ? All of these tubes hook up to ajunction that connects to your EGR solenoid. Better check your solenoid and see if everything is all hooked up.
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Old Nov 9, 2005 | 07:02 PM
  #12  
fire350tpi's Avatar
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From: Middleboro, MA
Car: 1988 Pontiac trans am/gta
Engine: 350
Transmission: 700r4
Axle/Gears: 3.23's
sure, i should have a picture tomrow, ill dbl check the soilenoid
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Old Nov 9, 2005 | 07:11 PM
  #13  
Red Devil's Avatar
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From: E.B.F. TN
Car: Tree Huggers
Engine: Do Not
Transmission: Appreciate Me.
North or south of Boston?
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Old Nov 10, 2005 | 05:39 AM
  #14  
fire350tpi's Avatar
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From: Middleboro, MA
Car: 1988 Pontiac trans am/gta
Engine: 350
Transmission: 700r4
Axle/Gears: 3.23's
erm, im not to good with direction, im thinking south ( middleboro)
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Old Nov 12, 2005 | 01:18 AM
  #15  
fitbmxseries1's Avatar
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Posts: 383
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From: fond du lac, WI
Car: 1988 trans am GTA
Engine: 350 tpi
Transmission: 700r4
i had the same problem i could hear hissing when i stepped on the gas and my car would hardly go i searched high and low for the vacume line but it ended up the valve cover wasnt sealed poperly... might be the prob might not be but its worth a try.
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Old Nov 12, 2005 | 07:04 AM
  #16  
fire350tpi's Avatar
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From: Middleboro, MA
Car: 1988 Pontiac trans am/gta
Engine: 350
Transmission: 700r4
Axle/Gears: 3.23's
thanks for the tip, in that case ill take a peak at the seal and try to listen for it, maybe throw a new gasket on there
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