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Registered
Join Date: Sep 2013
Location: Huntsville, AL
Posts: 621
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What is this on Airflow sensor?
On the volume airflow sensor is a 90 degree plastic elbow. A tube on the front of it goes to the idle speed control valve. What is the tube that connects to the back of the 90 degree elbow? (Not visible in picture)
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1986 911 3.2 Cabriolet "We all have a desire to create something that will show we were here. " Ferry Porsche |
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10-29-2015, 07:19 PM
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Registered
Join Date: Dec 1999
Location: Richmond, VA USA
Posts: 1,058
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The _copper tube_ connection on the forward side of the _rubber_ 90 is the vacuum source.
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10-30-2015, 05:11 AM
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Registered
Join Date: Sep 2013
Location: Huntsville, AL
Posts: 621
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Thanks!
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1986 911 3.2 Cabriolet "We all have a desire to create something that will show we were here. " Ferry Porsche |
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10-30-2015, 08:42 AM
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Schleprock
Join Date: Sep 2000
Location: Frankfort IL USA
Posts: 16,639
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The rubber tube on the back of the elbow, slightly larger diameter than the idle control valve hose, is a breather hose from the oil tank. There are actually two hoses back there that are the same size. One hose is the aforementioned hose that connects to the rubber elbow and the other hose connects to a breather neck on top of the engine case.
The reason the oil tank needs to breathe is because the breather neck on top of the engine case spits positive air pressure (and oil) into the oil tank. That positive air pressure in the oil tank needs to be relieved. So that relief is plumbed right back into the throttle body of the engine, via the connection to the rubber elbow. For performance/racing purposes, this breather to the elbow is often disconnected because you don't want to feed your engine oil vapor (or mostly oil, especially if overfilled) and burn it. So the breather hose is often connected to a "catch can" like this can I see oil vent catch cans
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Kevin L '86 Carrera "Larry" |
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10-30-2015, 02:25 PM
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