open loop vs closed loop?

i just got my turbotweaks chip sent to me and i was just wondering the difference between open loop and closed loop idle? are there any benefits to open loop?

Open loop idle in general is a smoother idle simply because it's running richer (in the 13-13.5 as apposed to the stoiceometric 14.7 of closed loop)

Closed loop used input from the O2 sensor to maintain 14.7:1 air fuel ratio.

Open loop does not use the O2 information but rather uses static tables in the chip, hence the richer tendancies.

Yes, reduced gas mileage, and better throttle response and increased emssions in open loop.