View Full Version : Closed loop operation

09-10-2004, 09:12 PM
Can someone explain what this is? I hear it all the time but don't understand. I only know that is part of the o2 system. Thanks guys. Just trying to increase my knowledge.

09-10-2004, 10:36 PM
Open Loop, closed loop. These are the two functioning states of your ECU. During open loop operations the ECU runs completely off of a pre-designed air/fuel map. When the vehicle reaches "operating temperatures" ie approximately 160*F or higher, it will enter closed loop operation. This is where it will still run off of its fuel and air tables, but it also relies on feedback from your lambda sensor (O2 sensor). Where it will modify your air fuel ratio by a certain amount to approach a predesignated ratio off of said readings.