What’s your objective?
There are some AFR parameters that can be “tuned” to influence the relatively brief operating periods when the ECU is operating in open loop mode.
In closed loop operation, AFR ratio is determined by the narrowband O2 sensors’ feedback.
The L31 was never equipped with a wideband O2 system and I’m not aware that the 0411 ECU can enable wideband operation. I’m sure someone else will speak up if that’s possible
I assume the L31 engine in your Cadillac is still equipped with the O2 sensors. I can’t imagine the installer would’ve eliminated them and run the system open loop.
Please confirm your engine is still equipped with the O2 sensors.
For the record, and to the best of my knowledge, the
only way for an individual to tune the 1997 black box ECU is using JET’s Dynamic Spectrum Tuner. A few members here, including myself, have this tool. Otherwise, there may be a third-party such as Blackbear Performance that can do it if you send it to them / exchange it with them.