Hey guys, I the scan tools and past tech ?;s i have noticed people mentioning closed and open loop etc...Can someone explain to me the difference between closed and open loop and so on?
thanks
Anything will help
Aj

 

In open loop the ecm takes/makes its calculations without consideration of the 02 sensor reading. Once the ecm switches to closed loop it will take (over time) averages of the 02 and try to balance it out to 14.7:1 (or stoich) Air / Fuel ratio. But Is still heavily biased to a table based fuel delivery calibration.

 

So closed loop is to be desired for the car to run the best?

 

yes, if u stay in open look you will use a lot of gas. Open loop is part of warming up the car. High idle and so on

 

For effeciency and emissions reasons yes. However the O2 sensor isn't at all accurate at WOT, which is why the ECM switches back to open loop when you floor it.