open and closed loop?

[ikle]

This is prob. a dumb question,but what does this mean "open and closed loop",just trying to learn,thanks,ikle

 

[87NAT]

When you start your car your chip is not using feedback from the sensors. The chip is controlling everything on preset parameters. After a certain temperature is reached the ECM goes into closed loop. Meaning that the it is now using the 02 sensor and other sensors to control fueling and such. This is a very brief explanation. It is much more in depth but I assume you get the picture.

 

[bison]

The sensor that is ignored in open loop is the O2. Other sensors are still used in open loop. Some chips idle in open loop to smooth out the idle even after the sensor is hot enough.