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Old 9th December 2007
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Default Vacuum Line blocked off??? (w/pics)

Any help is much appreciated.
Take a look at the pics. Does anyone know what the vacuum line that is blocked off does or goes to? It has a short piece of tubing with a scew in the end of it.
I found a vacuum line laying just below this with a T in it, but it was not connected to anything. Maybe it came from this? Is this a problem?

Normally there is a plastic air box covering this, but I took it off for the pics.

The car is a '98 900 2.3 non turbo with automatic tranny.

In case you don't see it, it is right above the second A in Saab.
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Last edited by wingnut; 9th December 2007 at 09:14 PM. Reason: add pics
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Old 9th December 2007
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It may be hard to tell, but it is attached to the same fitting as the larger line that is right next to it.
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Old 9th December 2007
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On the 2.3L non-turbo engine, both hoses lead to the throttle body. The large hose is connected above the throttle plate, and the small hose below the throttle plate.

When the engine is running at idle (or light load while cruising), the amount of fumes is less, the vacuum is bigger under the throttle plate, and the fumes are sucked into the engine primarily through the small hose.

When the engine is running on open throttle (or high load), the amount of fumes is greater. The throttle plate is wide open, and the crankcase is evacuated mainly through the large hose.
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Old 9th December 2007
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Quote:
Originally Posted by PMI
On the 2.3L non-turbo engine, both hoses lead to the throttle body. The large hose is connected above the throttle plate, and the small hose below the throttle plate.

When the engine is running at idle (or light load while cruising), the amount of fumes is less, the vacuum is bigger under the throttle plate, and the fumes are sucked into the engine primarily through the small hose.

When the engine is running on open throttle (or high load), the amount of fumes is greater. The throttle plate is wide open, and the crankcase is evacuated mainly through the large hose.
Is the benefit big enough to hook it back up?
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Old 9th December 2007
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Quote:
Originally Posted by wingnut
Is the benefit big enough to hook it back up?
Honestly, I am not sure. Issues with the crankcase vent system get discussed a lot on the turbo version of the engine, not so much on the 2.3L.

A better question is what else was done with the vacuum lines on your car. I am not aware of any lines with a "T" in them, unless they were put in by the owner.

On the turbo, people often use a T to connect an aftermarket boost gauge. On the non-turbo engine, someone might have used it for testing (?)

If I did not understand an engine modification, I would probably try to put it back to stock.

I would also check if the vacuum line from the throttle body to the fuel pressure regulator is intact, and that it holds vacuum. That one does have a function which is best not to mess with, it helps keep the fuel pressure at the correct level.
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Old 9th December 2007
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Thats what I was thinking, but I didn't clearly see where to hook it back up. I'll have to take a better look tomorrow. My car seems to be taken care of pretty well, so a hack job on the vacuum lines would surprise me. I found a few lines that were starting to dry rot, I think I may spend a few hours replacing them one weekend.

When I get a little time, I will find out where it goes, hook it up and see what happens.
Maybe i'll get an extra 300 HP out of it!
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Old 10th December 2007
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Quote:
Originally Posted by wingnut
Maybe i'll get an extra 300 HP out of it!
More likely, just a few extra mpg...
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