No pic, sorry.

K20 swap into Fiat X1/9.

There is what appears to be a vacuum switch on the upper water neck. One side of the switch routes via a vacuum hose to the intake manifold right beside the #4 runner. The other side routes to something that is absent from this engine.

 

If its what I'm thinking of, on the upper right side of the engine, it allows air to bypass around the injectors when the engines cold to lean the fuel mixture and help warm the engine quicker.

 

i think i had this same question, you can just plug it up.. i made a thread about it with pics a while back.. hope this helps

https://honda-tech.com/forums/acura-rsx-dc5-honda-civic-ep3-32/vacuum-line-q-2745236/

 

Cold start "enleanment?" That would be a new one for me.

This and the post above helped. The linked thread discussed exactly the piece I refer to. I will eliminate it altogether. One never knows when working with modern engines what will throw a code or trip a limp home mode.

Thanks!

 

Air Assist Valve: This valve allows for a faster warm-up in cold weather.
When the coolant temp is at 147 degrees or BELOW the valve is opened.
The air enters the AAV from the intake tract and routes the unmetered air thru a nipple on the IM, which feeds a cavity in the head behind the IM gasket, and then back thru the IMG and into ports in the fuel injector bosses in the IM. This allows for a leaner mixture, thusly a quicker warm-up.

There's a nice diagram too
http://www.ephatch.com/forum/content...r-Assist-Valve