What's this little gadget? abv?

[Dimmy]

I've come across a few issues with the gf's car (4agze with an sc14). When the car is at operating temps and after some driving with boost, when I come to a stop in traffic or light the idle seems to drop off very slowly from about 1100rpm to 900-1000rpm and in some cases stalls. It doesn't always happen and is only intermittent, i've checked all the vacuum hoses i could think of and couldn't find the culprit.

Yesterday i found a small split in a vacuum hose leading to the part in the pic, trimmed the hose and it does the same thing. I did notice that while this little thing was off the car, the boost gauge wasn't detecting a vacuum but the car did idle much better. Both connections are connected to a vacuum source.

Could this be what is causing the issue? is this the abv i seem to think it is

[Duk]

I'm pretty sure that's the solenoid valve that switches the pressure signal line for the fuel pressure regulator, between manifold vacuum and atmospheric pressure.
This is only done during light loads (off boost) and was some old emisions trick to spike the fuel pressure/add more fuel.
Mazda also used this set up on the Familia GTX.

[Dimmy]

Ok, well that would make sense because it does plug one end around the fuel pressure sensor. Is it needed? If its unplugged the idle increases to a normal/non-shaking level

[Duk]

I bypassed it on my car in an attempt to get more consistant low load AFRs when tuning. Never saw a need to re-attach it.

[X kyle X]

Is it what's called the fuel VSV...

Jump into the aw11 thread dimmy...they will tell you straight away..im just daft haha