Vacuum Confusion -SOLVED

[Gelbster]

Vacuum issues got you confused ? Can't find details of routing? Bewildered by the crummy diagrams that show only part of the system ? Got at least 6 different print-outs and they are all slightly different?
Today is a great day to be alive on the 986 Forum - because most of your prayers have been answered but the answer is buried here:
See post # 17 for layout :Oh no, another...
video is here:
https://www.youtube.com/watch?v=A731OcZVGTI&feature=youtu.be
entire thread is here :
Oh no, another...
Kudos to the author and a challenge to anyone to improve on it !

[78F350]

Thanks Gelbster! I'll post some of it here to make it easier to find:

First, let me explain, there are a few separate systems that use vacuum from the intake. The most common one to fail is the secondary air injection system. That is the one I replaced. The other vacuum users are the brake booster and the fuel pressure regulator. Both of these looked good, so I left them alone. ***Tiptronics have a vacuum line that goes to a valve on the transmission. 2.7L and 3.2L engines have a vacuum line that goes to an actuator for the flapper valve on the front cross tube.***

This diagram shows the simplest system: 2.5L manual trans.


SAI vacuum system:
***This is for U.S. cars, the SAI was not used in R.O.W.***
The SAI is an emissions system that pumps fresh air into the exhaust for the first minute or two after a cold start. Common DTC codes when there is a vacuum leak in the system are p0410 and p1411. A failure of the SAI system will not damage your car, but a vacuum leak may cause the engine to run lean and lead to other problems.
-Remove the throttle body and cross tube for access to the rear part of the system.
-Remove the alternator for access to the front part of the system.
-Pull out all the old tubing.
-I replaced all the tubing, but reused the check valve and Y.
-Put it back in connecting to: 1) Electric change-over valve. 2) Vacuum source at cross-tube. 3) Vacuum resevoir. (2.5L 5 speed models have the simplest system)
***recommended: Also replace the small tube that connects the electric change-over valve to the vacuum powered change-over valve.
-Reassemble everything else that was taken out.
Old:

New:

The video (Currently some sections of the forum allow videos to be embedded, some don't.):


Resonance flapper connection, 2.7L and 3.2L:



There are some other posts with good info scattered across the forums that we can collect and repost here:

-Brake boost vacuum line connects to right rear intake on the Tiptronics and the line includes a venturi.
-Brake boost vacuum line connects to the left front on the manual cars.
-Details about the flapper on the 2.7L and 3.2L.
Edit 5 Sept 2016: Added diagram showing resonance flapper connection.

[crwarren11]

Hoping for some help....please!! I removed tiptronic transmission a few months ago and get continued SAI error codes. I have rerouted all SAI lines and confirmed proper connection to each point (and presence of vacuum), EXCEPT for "I" noted above which apparently goes to a valve on the tiptronic. I cannot locate this valve on the tiptronic to connect this Y to. It is open and I don't see any other broken lines. Does anyone know which valve this connects to and/or do you have a picture of it / precise location where I can look? I searched for several hours above and below the car with no luck. Please help!

[78F350]

The change-over valve for the transmission cooling is at the rear, top of the engine, slightly to the passenger side above the starter. Vacuum source from the T should connect to the front of the valve. The other connection on the valve goes to the cooling valve on the transmission. I don't have a great pic handy at the moment, but this should help: