Please explain open/closed loop

[Luv2xlr8]

My 2012 1.8 auto Sonic stays in closed loop pretty much most of the time when car is warm, but the weirdest thing happens when decelerating. The scenario is as follows...

The car stays in closed loop while accelerating and as long as I'm cruising (part or light throttle). But when I totally let off the gas pedal from a cruising speed about two seconds later the car enters open loop. And it stays in open loop until I step on the accelerator.

Another wierd thing which happens at the EXACT same time the car enters open loop while decelerating it feels as though I tapped the brakes really quick, at which point the car decelerates at a faster rate of speed. (It kinda feels like engine braking)

So is this normal to save fuel or emissions?

Also while the car is warm in idle, it will go into open loop for about 5 seconds and it shakes and idles rough?

Is this normal as well? Any shop owners or anyone with experience please explain to me as I'm not that well experienced with this kind of stuff.

 

[Preloader]

Closed loop means the feedback from sensors mainly o2, but also knock sensor and cam position are being read and the info is processed and the fuel demand is then adjusted to maintain stoichiometric efficiency. 14:1 air fuel ratio.

Open loop means the feedback is overridden and a predetermined program is running the operation. Closed throttle at coasting speeds kicks on an open loop program that stops the supply of fuel to increase fuel efficiency and reduce emissions.

A more in depth explanation is available, but that is the short to the point answer I have to offer.