can use rs4 ecu on s4?

[Chodan]

I believe that the ECU of the RS4 or RS5 has a built-in G-force sensor and engine data sensors.
So, I’m thinking that if I purchase an RS4 ECU, apply the S4 software to it, and install it in my S4, all the features I want might work.
Fundamentally, since the RS4’s 2.9L engine and the S4’s 3.0L engine are similar, I assume that simply transplanting the software should be fine.
However, is this too naive of an assumption? Are there any other risk factors to consider?

[Chodan]

Or if I install a yaw sensor from a previous generation vehicle (B8), could the G-force meter work?

[Smac770]

The chassis dynamics sensors are in the chassis control module, not the engine control module.

[Chodan]

The chassis dynamics sensors are in the chassis control module, not the engine control module.

Thanks very much, I need to search more information about it


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[Smac770]

There are five different strains of the J775 chassis control module, base p/n 8W0 907 777. They will vary for adaptive suspension, sport rear diff, RS model, etc. The revision letter chains as the parts catalog seems to present them:

none > C, for A/S with adaptive suspension
A > B > R, for A/S with sport diff
E > H > T, for A/S with sport diff and adaptive suspension
L > P > S, for RS with sport diff
K > Q > AA, for RS with sport diff and DRC suspension

seems to be the revision chains. If your S4 has neither adaptive suspension nor sport diff, you probably don't even have a J775 present. The J775 is at 74-chassis control in a VCDS scan.

[Chodan]

There are five different strains of the J775 chassis control module, base p/n 8W0 907 777. They will vary for adaptive suspension, sport rear diff, RS model, etc. The revision letter chains as the parts catalog seems to present them:

none > C, for A/S with adaptive suspension
A > B > R, for A/S with sport diff
E > H > T, for A/S with sport diff and adaptive suspension
L > P > S, for RS with sport diff
K > Q > AA, for RS with sport diff and DRC suspension

seems to be the revision chains. If your S4 has neither adaptive suspension nor sport diff, you probably don't even have a J775 present. The J775 is at 74-chassis control in a VCDS scan.

I checked the specifications of the 2022 S4 in South Korea and found that it comes with the 8W0 907 777 T module, even though the rear sport differential is not equipped.

While I’m not sure about sensors like the G-meter, it seems possible that the rear sport differential could function if the hardware is installed.

Thanks for the information!


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[Smac770]

But did it have the 2MV adaptive suspension? It appears the x > C chain got abandoned; it could be they ended up "simplifying" to just the R (sport diff without adaptive suspension) and T (adaptive suspension, with or without sport diff). Audi doesn't really explain; we're left having to try and work it out. If the vehicle was 1BD (standard S-model suspension) and GH1 (standard rear diff), there would be no reason for it to have a J775. 2MV is the adaptive S-model suspension, and GH2 is the sport rear diff.