I’ve bought the SLC Free 2 controller with the corresponding LSU4.9 sensor and done all the wiring and soldering.
I tried to test the system using the test with free air, with the lighter gas and another test but results do not seem right :
Free Air Test : Directly after powering the board, the screen shows a lambda = 1 (initialisation) and the temperature shown is already close to the operating temperature (~780°C). After about 5 seconds, the lambda value converges to the saturating lean mixture value of 1.36 (5V on linear output and 0V on the simulated narrowband output). This test looks to be good. However, the initial temperature shown is already close to 780°C directly after powering the board, is it normal although the internal heating element is initially cold ?
Sensor test with the lighter gas : Again, the test starts in free air, the behavior explained above occurs. After waiting about 1-2 minutes to ensure the correct settling time, I approach gas from the cigarette lighter but nothing changes, the lambda value still satures at 1.36 (while the temperature remains constant about 780°C).
Another test has been done in the exhaust gas of burner. I wanted to make sure that the measuring error was not caused by not being in a hot enough environment. The combustion gas had a temperature close to 350-400°C. Again the 1.36 value does not change although the combustion gas has a low enough O2-concentration (about 14-15%).
- The 0 Ohm resistor has been soldered to short both GND.
- Continuity tests between the LSU4.9 sensor and the board have already been done and the connections look okay.
Do you have any idea where this measurement problem can come from ?
Thanks in advance !