Car is in open loop when it is cold. This means the ECU is running the engine off of predetermined tables and ignoring the inputs like the O2’s, ECT, ACT, MAP, and O2’s.
When it goes to closed loop is when it starts using all those inputs to trim the fuel to attempt to run at a stoichiometric ratio of 14.7:1.
I am not sure when it goes into closed loop as I have read it’s based on the O2’s heating up and is anywhere from 30-120 seconds or it’s when the ECT registers 140 degrees or so. Someone will chime in with more knowledge than me on that.
Reason I am bringing this up is if the car is running fine in open loop then goes into closed loop and starts to run bad it could be that one or some of the sensors providing input are bad. This should show up in a code.
When it goes to closed loop is when it starts using all those inputs to trim the fuel to attempt to run at a stoichiometric ratio of 14.7:1.
I am not sure when it goes into closed loop as I have read it’s based on the O2’s heating up and is anywhere from 30-120 seconds or it’s when the ECT registers 140 degrees or so. Someone will chime in with more knowledge than me on that.
Reason I am bringing this up is if the car is running fine in open loop then goes into closed loop and starts to run bad it could be that one or some of the sensors providing input are bad. This should show up in a code.