Hey
After getting the engine warmed up, does the PCM switch to closed loop and stays like that, or does it keep on switching between open and closed loop? Is the open loop only related to cold engine temperatures or are they other factors?
What vehicle is this?
I am talking in general
But last weekend i was working on a citroen cactus, when i displayed the up stream and down stream o2 sensors status, the upstream was in closed loop, but the downstream was in open loop, when i rev the engine, bit changes to closed loop
I also read this online :
Open loop is when the ECU is not referring to the o2 sensor for feedback. Meaning that the o2 sensor might as well not be there, because the ECU is not using it to modify its timing and fuel maps. If your asking yourself why the ECU would ever want to do this? It is because there are times when you want the motor to run a set amount of timing and fuel, no matter what the conditions. For reference, most OEM cars are tuned to run closed loop o2 on partial throttle driving to get the best gas mileage, and then run open loop on wide open throttle (WOT) to be sure the motor runs the safest it can, and that the factory fuel map is not modified in any way. Closed loop is when the ECU does refer to the o2 sensor for feedback. Using the o2 sensor the ECU will modify its fuel table based on the readings the o2 sensor is seeing. This is important in maintaining a perfect A/F ratio as there are so many variables affecting the tune of a motor at any given time. For example, air temperature, altitude, humidity, and so on.
please provide your vehicle info per the instructions.
There are a few factors. Temperature is the predominant one.
https://www.hotrodhandbooks.com.au/eBooks/TPI/TPI%20On%20Line-03-2.html
The engine will stay in closed loop until the next time you start the engine. However, if you start a warm engine, it will start closed-loop operation quicker than a cold engine.
I am talking in general
But last weekend i was working on a citroen cactus, when i displayed the up stream and down stream o2 sensors status, the upstream was in closed loop, but the downstream was in open loop, when i rev the engine, bit changes to closed loop.
Is it just a bad sensor?
I also read this online :
Open loop is when the ECU is not referring to the o2 sensor for feedback. Meaning that the o2 sensor might as well not be there, because the ECU is not using it to modify its timing and fuel maps. If your asking yourself why the ECU would ever want to do this? It is because there are times when you want the motor to run a set amount of timing and fuel, no matter what the conditions. For reference, most OEM cars are tuned to run closed loop o2 on partial throttle driving to get the best gas mileage, and then run open loop on wide open throttle (WOT) to be sure the motor runs the safest it can, and that the factory fuel map is not modified in any way. Closed loop is when the ECU does refer to the o2 sensor for feedback. Using the o2 sensor the ECU will modify its fuel table based on the readings the o2 sensor is seeing. This is important in maintaining a perfect A/F ratio as there are so many variables affecting the tune of a motor at any given time. For example, air temperature, altitude, humidity, and so on.
when i displayed the up stream and down stream o2 sensors status, the upstream was in closed loop, but the downstream was in open loop,
O2 sensors don't have a loop.
Engines have fuel control loops. One per bank.