Fast Idle Selenoid. How important is it. I just realized that mine is missing it's wire. (Not hooked up)

There are 2 fast idle devices on MPFI EA82's

 

 

There is one on top of the termostat housing that controls COLD FAST IDLE which idles the car up when cold to warm it up faster and make it drivable in cold weather.

 

Then there is a 1 wire unit right on the throttle body that raises the WARM IDLE when the A/C compressor kicks on to compensate for the drag it puts on the engine.

So, no AC no fast idle needed?

So, no AC no fast idle needed?

 

Correct.

 

 

You still do need the other one for COLD fast idle unless you live in a place where its allways warm year round.