O2 Signal fluctuates between 1V and 50V after switching to Narrowband

[polok]

"Hello,
I am using a Hondata KPro V4. A year ago, my car was professionally tuned using a PLX wideband sensor. Now, I need to pass the German 'TÜV' inspection (equivalent to MOT in the UK or Safety/Emissions in the US). For their diagnostic software to pass the car, they need to see a fluctuating voltage signal from a narrowband/stock O2 sensor.
My goal was to temporarily switch back to a narrowband (stock) sensor for the inspection. However, I am facing the following issue:

The Problem: In the KManager software, the 'O2' reading shows a fluctuates between 1V and 50V and the Lambda value is frozen at 0.69.
Physical Measurement: I have measured the signal at the ECU pin input, and it correctly fluctuates between 0.1V and 0.9V.
Software Settings: I have updated the settings in KManager to 'Narrowband' under the 'Closed Loop' tab.

Despite these changes, the software does not seem to process the actual voltage arriving at the pin. Since the calibration was originally created by a tuner, I am wondering if there is a fundamental setting or a specific lock/modification in the software that prevents the ECU from switching back to the narrowband input.
I have basic knowledge of the software but am stuck at this point. Any advice on what to check in the calibration settings would be greatly appreciated."

[Spunkster]

What vehicle are you referring to?

What is your ECU part number?

[polok]

It´s a Lotus Elise with K20A2 engine and the ECU number is 37820-PRA-E2

[Spunkster]

Post the calibration used

[Arno]

It´s a Lotus Elise with K20A2 engine and the ECU number is 37820-PRA-E2

I suspect your tuner used a PRB calibration to use the external wideband as that's usually required because the PRA codebase does not have the required logic in the code to handle the wideband data.

To get the narrowband to work you will likely need to copy and paste all the data from all screens from your current (PRB based) configuration to notepad or similar, then open a new/fresh PRA calibration and copy all the values in notepad back into the new calibration and then upload that to the ECU.

Unless Hondata can confirm that the PRB codebase should work with a narrowband too.. Then I'm just barking up the wrong tree...

Bye, Arno.

[polok]

Thank you for your quick response. I’ve attached the wideband sensor calibration and hope the issue is related to the map.

[Spunkster]

It is a PRA calibration but it is set to read an external wideband input to the K-Pro. We cannot really assist with trying to get an emission test to pass as this system is not designed for that.

[polok]

Yeah, I know that with this calibration you don’t see any O2 voltage. Tomorrow I’m going to flash k20a2-civictyper-tuned.kal from the Hondata list. With that one, the O2 sensor always showed the correct values and lambda control was working as well.

[polok]

I flashed the base calibration k20a2-civictyper-tuned.kal, which has always worked properly. The O2 voltage was correct, and lambda/AFR control was functioning. I’ve recorded the current behavior with the wideband and narrowband sensor and will attach it.