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Originally Posted by tomtom72
May I climb that curve with you? 2nd gear w/key on, right...to get up this hill?
I just think that ya also need to realize which side of the flow chart each read out is comming from....ya know is it data from a feed back leg or a control leg... 
MHO: O2 = feed back side
Int # & BLM # = control side........
What do you think?
Tom |
Tom,
The reason its called "closed loop" is because the O2 sensor provides the results of the current BLM/INT levels and the ECM uses that input to modify the BLM/INT on a continuous basis. Running Open Loop means that the ECM will use whatever fueling is in the VE tables with no mod based on O2 sensor input. That why in O/L, your scantool will show BLM/INT values of 128. ECM makes no changes to current fueling. Closed Loop also brings in other routines like Proportional Gain, DFCO, DE, and the Integrator. Usually these are referred to as PID controls. For instance, some people complain of steady state surging that occurs once the motor is warmed up. That's because it goes into Closed Loop once the O2 sensor is warmed up and the C/L params are met. The surging can be caused by Proportional Gains that introduce too much or too little fuel for the given airflow or O2 voltage or both.
So the O2 is as much about control as anything else. The BLM/INT don't exist independent of that.