I would guess it may be stock and require vats off. Can you remove the blue cover and take a photo of the chip?

I would take a guess that the memcal needs the VATS (vehicle anti theft system) disabled. If you can take the cover off the ecu and get a photo of the memcal and see if there are any stickers or writing on it would help to confirm.

What is it exactly you’re trying to change?
The XDF is only a viewer so changing scales in the XDF will not change them in the bin

J1939 is pretty clearly defined for many parameters on the CAN network, but there are some manufacturer specific items still available. As much as J1939 is “defined” not all parameters/messages are available or supported by all manufacturers or required depending on the vehicle. Typically you don’t ...

Simplest way
Read bin file from memcal, identify matching XDF and turn VATS off in bin file, erase memcal with UV eraser and then burn new bin file onto the memcal.

There are other ways that involve replacing chip with an EEPROM or NVRAM.

Alternatively find someone on here that can do it for you

Need to get a log of commanded AFR vs a wide band AFR.
The commanded AFR is affected by many things, coolant temp, TPS%, time at WOT, RPM etc
It can vary a lot based on these settings.

Given he’s running an auto (I assume VT 4L60E) will need a 424 ECU and 11P to run the electronic auto

Do a comparison between a standard Holden bin and an equivalent HSV bin to see what they changed.
This will give you a good starting point.

Good to hear it’s sorted.

I’ve seen a leaking diaphragm on the fuel regulator do this. Excessively rich at idle as fuel was being sucked in the vacuum hose into the engine. Try pulling the hose off and check for any fuel in the hose or leaking out of the regulator.