Newly acquired 914, 1976 2.0. Has missing vacuum hose. Does anyone know what it hooks to? This causes the car to idle high, I put my finger over it and the idle dropped from 1700 down to 500 rpm. Is this causing a lean fuel-air mixture? Thanks
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Goes to the deceleration valve.

I think the fitting that goes there looks like a F

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http://www.914world.com/bbs2/index.php?showtopic=62002

On earlier models, the f would go there. That later port is way too small for the f I have on my 73. Did they have a smaller f for late models?

At the very least plug that hole. Do an inventory of the parts you have and then figure out what you might need and how to connect them. Its not that hard.

Krieger is right. If someone deleted the decel valve you can simply cap that connection so it's not a vacuum leak anymore. With stock fuel injection you really should acquire a decel valve and plumb that back in, however. It prevents damage to the MPS on hard overrun.

Also, FWIW, that leak isn't really making you run lean. It's just giving the engine more air just like when you open the throttle.

Later cars didn’t have the ‘F’ piece.

You guys are great! That JeffBowlsby link even tells me the size hose it needs! The deceleration valve is there. What is strange is I got the car from a classic car dealer in Houston where they did a tune-up on the car before I bought it. The car takes a while to warm up, like it's a little lean, wants to die when backing out of the driveway. After it warms up it is fine. The tires are a little tall not sure if that is contributing 205/70-15.

if it is anything like an L jet the warm up weak idle might be due to the AAV (aux air valve). ie its closing too quick or not opening at all for extra intake air when the engine is cold.

This sounds about right, I bet it's not opening at all. It dropped to 500rpm Ice cold when I covered the hole. Maybe I can take it off and soak it in something.

You have the right idea. If you remove it it's very simple to bench test. Connect the lead to the positive terminal and ground the body of the AAR. It should go from fully open cold to fully closed in like 5 to 10 minutes. If not, yeah, clean/soak/etc. Watch Ian's video.

not a D jet man, but i'd guess the rev drop is because the idle is set currently with that extra air entering via the open port. its like you have an idle port without the adjustment screw. you will need to reset your idle with that port blocked or correctly connected to decel.

advice to cap the port for now if you can't hook up to decel valve is good.
its only a small port but its sucking in unfiltered air and ........dust/dirt.

you can run L jet without the decel. but i hear D jet needs it. as advice above says.

EDIT - you will need the car fully warmed up to reset steady idle.
then you can address the weak start up idle at cold.
the AAV is an older style on the D jets and i don't know much about them.
i'm currently investigating a weak AAV on my L jet.
its really only a bug bear on cold start and i kind of put up with it for now.
not much you can do with the AAVs on L jet except clean them out.
but the "springs" (electric heated coil) do go weak with age. i assume D jet AAVs suffer similarly.

Not true. You really need the decel valve in the L-Jet to keep it from dying when the throttle snaps closed.

Clay

yeah - i don't seem to have that problem clay.
and its been like that for 33 years.
has a fuel pressure regulator subbed in as a visual emission cheat done by original owner.

but i've been thinking about what you say and i figure it might have something to do with all the slight variations on L jet we found after mr bolwsby prompted the search for the EC-A, EC-B versions of 74 that lead to the two different versions in 75.

i've got the version with the vac advance hook up off the distributor to the throttle body.
the EC-B 49 state car of 74.

i'd have to think about it more but i wonder if this does not make it come down so savagely without the decel. the L jets without that hook up might behave slightly differently.

anyway its never been a problem on mine, though i have a decel sitting around now and just have to tweak the bracket and test it to put it in. when i get around to it i'll report to you on the difference.

I made a video on restoring the AAR. It assumes the wire is still intact and the heating element works. There was also a recent post about replacing the heating element.

https://youtu.be/cBdjLrxvBIM