308 Electro-valve with a 'Missing' Hose?

Greetings to all. I was working around the 308's engine yesterday, and was reminded once again of a slight head-scratcher that I have had ever since I bought the car (1980, USA 2-valve fuel injected).

There's an electro-valve located on the top of the frontmost cam cover, close to the cam belt guard end. The first picture shows the location; I have circled and arrowed the electro-valve in the photo. The valve has a pair of vacuum hoses attached to it - one leads to a diaphragm which you can see in the photo, while the other one leads to a fitting on the intake plenum (a bit harder to see in the photo). There's also a pair of electrical wires which presumably trigger the valve to be open or closed.

However, the puzzler bit is that the valve also contains a spare unused hose nipple which is sized to accept a similar-sized vacuum hose. See the second picture, with an arrow pointing to this mystery hose nipple - this second picture was taken thru the opening between the deck hatch and the rear window, looking rearward. On my car, there is nothing attached to this nipple, and in looking thru the various owner's manuals, parts books, and service manuals, I have never been able to find any mention whatsoever of a hose which is supposed to be attached to this port. Nor could I locate any references which clearly explained specifically what this valve does.

So, with this as a background, here's my questions:

1) It strikes me as quite odd that the hose nipple intentionally has nothing attached to it - Is this indeed as it is intended to be? I have looked about, and can find no other obvious attachment point for the "other end" of such a potential hose to connect.

2) Assuming for the moment that the hose nipple is supposed to be open to the atmosphere with no hose attached, exactly as it is shown, it seems to me that, when the electro-valve is activated, there's a probability of unfiltered air to enter into this nipple and from there make its way into the intake plenum. Granted, the area of the nipple is small enough that there's not a large amount of unfiltered air which could enter, but, still, it seems a bad idea in general principle to have any unfiltered air, no matter how small the amount, potentially entering into the plenum.

3) As an aside (since I now have your attention fully focused upon this lil' bugger), does anyone know the specific function of this electro-valve? Since my copy of the same year Euro engine parts manual does not show this electrovalve / diaphragm / hose arrangement at all, my best guess is that it is related in some manner to a cold idle USA smog requirement of the day. But how is it supposed to work?

Can anyone enlighten me on this one?

Thanks and Cheers - DM
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Steve - Thanks for your explanation concerning the electro-valve nipples and the "missing" hoses. That makes perfect sense!

I've been doing some more research since I posted my inquiry with pictures here yesterday, and I believe that I can now answer my own question.

I am 99% certain that the specific electro-valve which I have discussed in this thread is the controller for the infamous "2500 rpm idle while stone cold" feature. This electro-valve opens or closes a vacuum line which connects the plenum to a large diaphragm (which is visible in one of the pictures). The electrical signal for the electro-valve seems to come via the extra temperature sensor switch which is mounted onto the bottom of the radiator expansion tank. This diaphragm in turn operates a secondary air passageway which allows for the dumping of a large slug of excess air from the air cleaner into the plenum, thus forcing the cold engine to run at a fast idle.

The device actually serves broadly as a secondary Auxiliary Air Valve for the fuel injection system ... but it can certainly be argued that the engine does not really benefit from having -two- of these idle air enrichment devices!

This explanation also justifies why this device can't be found on the similar Euro versions from this era, since this requirement was forced upon the USA versions of this car in the name of reducing emissions.

It strikes me that this is simply yet another of the rinky-dink (i.e., arguably state-of-the-art and well intentioned at the time, but from today's perspective more than a bit crude in function and execution) smog devices which the USA spec cars were forced to suffer at the time.

Thanks for all of your feedback

Cheers - DM