MSS54 ADC inputs

[MpowerE36]

Hi,

I would like to know if someone has the voltage range of each ADC inputs of the MSS54 ?

In particular, I would like to know if the O2 sensor ADC input is a 0-1V input or a 0-5V input which is not used on its full scale ?

[Tomba]

I believe the maximum voltage is 1.2V in diagnostics. They might used an amplifier circuit to range up the resolution. In software its divided again to show the correct value on diagnostics.

[SliM3]

Minimum voltage = 30mV / Maximum = 1000mV
AFR reference voltage = 450mV

[S54B32]

I traced the lines on the pcb, there is a IC-amplifier before the AD-converter.

[MpowerE36]

Thank you very much for your answers. I had the idea to use a second generation of O2 sensor to do closed loop at WOT but if the maximum value of the input is 1000mV, it will be difficult unless per-processing the signal of the new O2 sensor. But maybe there are two unused 0-5V ADC inputs in the MSS54 ?

Of course it will need a specific tune & program with major modifications. At least :

1) Change gain and offset of O2 sensor signal (K_LA_M & K_LA_NP)
2) Open [K_LA_UM;K_LA_UF] range
3) Create a second target K_LAS_R_FETT_VL which will be used at WOT (or better a KL_LAS_R_FETT_VL(rpm))
4) Maybe other modifications

[eacmen]

Has anyone done closed loop WOT on a standalone ECU? Is there worthwhile gains to be had?

[Martyn]

I run closed loop WOT on my Infinity, it's great to keep a fixed AFR whilst tuning without having to worry but once tuned you want the trims as small as possible in case of sensor failure etc.

[MpowerE36]

I saw that most of wideband AFR gauges have an analogic narrowband output (0-1V) or a tunable analogic output (voltage VS lambda or AFR). So in this case, it would be possible to connect this output to the original precata O2 sensor inputs of the ECU. Then it is "only" necessary to make a specific tune & program to do closed loop at WOT.