hello
The aux valve create a small vacuum leak when the temp outside is cold
to move up the idle.I think aroud 300 rpm more than the base idle  aroud
850 when  the aux is fully open
The engine gone a start good but no fast idle  may be it will stall and
you gone have a rough idle when is cold .  At minus 20 probably the
engine will be flodded of gas  not enough
air for cold start

Denis