2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Indications of a vacuum leak

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Old Oct 9, 2002 | 01:53 PM
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Indications of a vacuum leak

what are some good hints that ur leaking.
and what can u do to fix.

thanks
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Old Oct 9, 2002 | 02:58 PM
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Bad idle, low gas mileage, lack of power..........
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Old Oct 9, 2002 | 04:10 PM
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...low vacuum reading on your boost guage, hissing from engine bay...

To fix, once you find the leak, plug it. This normally involves replacing the hose that is leaking.
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Old Oct 9, 2002 | 04:38 PM
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Give your suspected area of leak a good shot of Starter Fluid. Pay particular attention to the engine revving up when you spray It. If this occurs, you have localized the leak, atleast. Spray while car engine Is on ofcourse.
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Old Oct 9, 2002 | 04:44 PM
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my vacuum at idle is about 15-16.
my idle sucks once in a while.
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Old Oct 9, 2002 | 06:24 PM
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question: is there any specific spots where a leak may develop on alot of fc's? any specific hoses prone to failing?

mike
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Old Oct 9, 2002 | 09:08 PM
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Mike,

Your vaccum at idle is SOLID! I highly doubt that you have a leak. What gives you the idea that you have a leak?

Josh
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Old Oct 9, 2002 | 09:53 PM
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From: Queens, NY-----Rockland, NY(School)
my idle is rough when i first start it once in a while. its KINDA hard to start here and there.
if im pushing the car hard, and i come to a stop quickly, or just put it in neutral, it will sometimes stall. it dips down close to stall speed when i put the clutch down.
but most of the time it idles alright, smooth, no misfiring or anything.
sometimes i get good power, sometimes i dont, its weird.

mike
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Old Oct 10, 2002 | 12:48 AM
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well the power thing I am not really sure. The other problems seem to be kinda normal. Or at least normal to me with my 89T2. When I am crusing and put it in nuetral to brake the tach drops to about 300 rpms then moves up when I stop. My idle is normally about 700 but when it idles strange it is around 400.
What year is your fc?
if it is a S4 you can adjust your TPS otherwise I think it is kinda normal on a S5
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Old Oct 10, 2002 | 01:46 AM
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OK, for the "idle-drop-to-almost-stall" issue, clean your BAC, and give your TPS a thorough test (and ofcourse correct if necessary)

As for the leaks, they should be relatively easy to discover. Either CC or starter fluid would do the trick (first will stall the engine if sucked through a leak, second will make the engine rev-up). Try to be thorough and methodical (dont go over and over the same spots).

Another solution is to just take off every plastic and rubber hose and check For example, my TID was cracked, and no matter how much CC I sprayed, I couldnt find the leak. After I removed the TID for the first time, I immediately spoted the crack (kinda hard to miss it, the crack was like 5cm long )
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Old Oct 10, 2002 | 06:51 AM
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Your vacuum readings at idle are pretty good, assuming your idle is set at 750 rpms. If idle is set higher, it may not be as good.

For the big dip in rpm when you put in neutral or come to a stop:

check your dashpot

It is supposed to make contact at 2,100 rpm and dampen the closing of the throttle plates. This may help you.

Hugues -
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Old Oct 10, 2002 | 07:03 AM
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mine feels like its going to stall to when i push in the clutch and let it idle but my tps is at 1ohm, maybe i should try and adjust the dashpot just a little bit tho..hmm
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Old Oct 10, 2002 | 07:25 AM
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questions:
any prefered way to clean the BAC?

Dashpot? wheres it at? might the last thing i never heard of=)
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Old Oct 10, 2002 | 07:42 AM
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Originally posted by BlackFC_NYC
questions:
any prefered way to clean the BAC?

Dashpot? wheres it at? might the last thing i never heard of=)
Carb or Brake Cleaner will do just fine. You can also use some gas, just make sure that you let it dry completely afterwards

The dashpot is a little "spring", which grabs the throttle cable when you let off the gas and lets it return to its idle position smoothly, in order to prevent any sudden bucking of the car....Its located under the IC, top right corner of the engine as you are looking at it when you open the hood. Its "resting" position can be adjusted via a bolt, and you can experiment a bit, until you find the right spot....Shouldnt have anything to do with this problem though...
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Old Oct 10, 2002 | 08:12 AM
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From: Queens, NY-----Rockland, NY(School)
chances are its the BAC then.
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