rendoll911 Posted September 19, 2011 Share Posted September 19, 2011 (edited) I'm looking to see if anyone can identify this possible missing vacuum hose on the intake manifold. I just noticed it today when i was changing my spark plugs. The engine bogs down when i cover it with my finger, there is vacuum present at this connector. It is the silver vacuum port dead center of the photo. Also there is a vacuum hose directly below this port connected to a vacuum line with a T connector and inline filter. The car is a 99 outback, but the engine is from a 96 legacy. Thanks for any help. Edited September 19, 2011 by rendoll911 Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted September 20, 2011 Share Posted September 20, 2011 It goes to one of three things. The Map sensor on the passenger strut tower. The fuel pressure regulator. Or the Evap purge control solenoid under the intake runners on that same side of the engine. If your hood is the original hood for the car it should have a diagram of all the vacuum lines on the engine. Quote Link to comment Share on other sites More sharing options...
rendoll911 Posted September 20, 2011 Author Share Posted September 20, 2011 The problem is my hood shows the diagram for a 99 engine and this is a 96. The diagram on my hood only shows one hose coming from this area. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted September 20, 2011 Share Posted September 20, 2011 the 99 has only one line going to the strut tower and the 2 devices are in line, one connects to the other. the 96 has 2 lines going to the strut tower, one to each device. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted September 20, 2011 Share Posted September 20, 2011 Ok, then just plug it and it should be fine. You want what's on the engine to match the original routing as closely as possible. If there was only one hose there before, and that hose is hooked up, then it's just an extra port that can be plugged off no harm done. Quote Link to comment Share on other sites More sharing options...
rendoll911 Posted September 20, 2011 Author Share Posted September 20, 2011 Ok, then just plug it and it should be fine. You want what's on the engine to match the original routing as closely as possible. If there was only one hose there before, and that hose is hooked up, then it's just an extra port that can be plugged off no harm done. I was thinking i'd do that, but when i block that port it bogs the engine down like its going to stall, then the idle speeds up to save it Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted September 20, 2011 Share Posted September 20, 2011 then get another ''T'' and a section of vac line and tie it into the one going to the strut tower. as a matter of fact, double check that the all of the line on the existing ''T'' are connected to something. the third leg may be loose. Quote Link to comment Share on other sites More sharing options...
987687 Posted September 20, 2011 Share Posted September 20, 2011 I have that too. On my 98GT the original 2.5 only had one nipple there, and the engine I swapped in had two. I just covered it off. No CEL codes for evap or any crap like that. Quote Link to comment Share on other sites More sharing options...
rendoll911 Posted September 20, 2011 Author Share Posted September 20, 2011 then get another ''T'' and a section of vac line and tie it into the one going to the strut tower. as a matter of fact, double check that the all of the line on the existing ''T'' are connected to something. the third leg may be loose. Just double checked. All the lines are connected. I'll try tieing it into the other strut tower since it seems like its causing engine hesitation when i just block it off. Quote Link to comment Share on other sites More sharing options...
987687 Posted September 20, 2011 Share Posted September 20, 2011 Just double checked. All the lines are connected. I'll try tieing it into the other strut tower since it seems like its causing engine hesitation when i just block it off. Since the engine is accounting for the vacuum leak, when you block it off it starts running a bit rich. Block it off right there on the intake and it'll be fine. With a leak like that, if you drive through something really dusty you could get a lot of dust in the motor. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted September 20, 2011 Share Posted September 20, 2011 I was thinking i'd do that, but when i block that port it bogs the engine down like its going to stall, then the idle speeds up to save it The ECU has adjusted idle speed and fuel mixture to account for more air entering the engine through that nipple. Plug it off and disconnect the battery for a few minutes to clear the ECU then reconnect and let it re-learn the fuel settings. It will probably run a little strange for a few minutes while it figures out the best mixture and adjusts idle speed. Quote Link to comment Share on other sites More sharing options...
Xist Posted September 2, 2015 Share Posted September 2, 2015 I know this is old, but I just wanted to add that on my 99 Forester, I have a hose running from here to my cruise control. For some reason, when I replaced my head gasket this hose really wanted to go the wrong way, so that was a bit of a decoy. Someone over at SubaruForester.org was kind enough to set me straight. Quote Link to comment Share on other sites More sharing options...
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