Wideband project for my MSS50

[MpowerE36]

Hi everyone,

I've started a new project to integrate two wideband oxygen sensors into my E36 M3 3.2L (MSS50 ecu).

The main motivation behind this project is that it's very difficult to achieve optimal AFRs in open-loop operation under all conditions (intake air temperature, atmospheric pressure, fuel quality).

To achieve this, I'm developing:

1. An electronic and mechanical interface using wideband controllers with simulated narrowband outputs.
2. A smartphone application to monitor AFRs and oxygen sensor temperatures in real time (example below).
3. A custom version of the MSS50 software featuring:
   • A new control strategy for the oxygen sensor heater relay.
   • Closed-loop operation enabled at full load.
   • True PID control (the original partial load control based on narrowband signal uses bang-bang control)
   • A configurable full load lambda target map (λ = f(RPM)).

BMW developed this type of strategy starting with the M3 E9x models.

[paulpbmw]

Very cool stuff man, for the few of us that have an MSS50. I purchased a Spartan 3 Lite V2 wideband from 14point7 which has a simulated narrowband output as well as a Bosch LSU ADV sensor for more resolution.
Im just getting around to tuning for a stock motor with kat delete setup as you know. My AFR was reading 15.1 at full load with stock tune and no kats. Very dangerous !!
Your idea is a very good one even if im the only other person who thinks so

Tuning the partial map is harder than the full load. One horrible mistake people are making on this forum is suggesting to turn off adaptions. I did this and noticed how my oil temp went straight to 300 F. IDK how it works on s54 but on s50 its no good

[Grime]

Very interesting project. The ability to run true closed-loop wideband control at full load and have a configurable lambda target by RPM would be a huge improvement over the stock MSS50 strategy. The real-time AFR monitoring through the app is a nice touch too. Looking forward to seeing how the interface and custom software develop.