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.