[Gmecm] RE:can't keep car in closed loop

[RogeranCarol]

BlankCurious if your open/close loop cycle changes with RPM. Could be your 
O2 sensor is not staying hot enough to
generate an output. No O2 output equals open loop operation. You imply you 
have scan capability; if so, check O2 voltage
while at idle and again at approximately 2000RPM. The sensor should be 
rapidly changing between approximately .2v and .8vDC.
Also, you should confirm the ECM is seeing the proper engine temp. The 
three operational requirements for closed loop
are Time since engine start, Engine coolant above set level and an O2 
signal varying below and above approximately .45vdc.
Good luck
Roger


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