Open Loop Mode during idling
I had opportunity to make some more observations with the help of the Torque app. In brief the observations were- When idling or running at low speed or when the accelerator was lifted, the ECU always switched to Open Loop mode.
- There was one instance when Torque reported running in Open Loop mode because of low temperature.
- There were several instances when system failure was reported at the time when erratic performance was being experienced.
- Erratic performance was always at low speeds/engine RPM
So what I would like to know now is exactly when the engine should be running in Open Loop mode and for that I consulted Lambda Power and this article.
Open Loop Mode not expected at Idling
Summarising it states, for a narrow band sensor, that
- Open Loop will be used during accelerating and decelerating/engine braking
- Closed Loop is used during idling and part load conditions
That makes sense because taking O2 readings is a process that incurs a certain amount of time lag. Therefore, Closed Loop would not be suited to rapid changes in engine loads but is suited for idling. Unfortunately, at idling the opposite Open Loop is being observed!
My next questions are "How does the ECU decide when to swap modes?", "How can I verify the operation of the O2 sensor?"
Some work on this has already been carried out and described briefly in the previous post. Namely, observing the O2 values whilst artificially introducing excess air to weaken the mixture and then doing the opposite by adding propane. These tests seemed to indicate the sensor was functioning, but well enough?
Support for an O2 (Lambda) sensor fault
A little bit more research on the Lambda Power site reveals these comments. The O2 sensor can be a cause of poor idling and engine racing that is often attributed to the idle control valve.My next questions are "How does the ECU decide when to swap modes?", "How can I verify the operation of the O2 sensor?"
How does the ECU decide when to swap modes?
A quick search for answers to the first question was unsuccessful but an obvious answer would be the accelerator/throttle position. More information is needed before pursuing this line of investigation of fault cause.How can I verify the operation of the O2 sensor?
For this I have once more consulted the helpful Lambda Power site and these articles.Some work on this has already been carried out and described briefly in the previous post. Namely, observing the O2 values whilst artificially introducing excess air to weaken the mixture and then doing the opposite by adding propane. These tests seemed to indicate the sensor was functioning, but well enough?
