Originally Posted by
svtmerc
I don't know.... lol
The consensus on the XF group on FB is that the V8 throttle body and adding the stock MAF sensor to the V8 housing work fine without any tuning needing to be done... although my logic says that the MAF being in a larger housing would require a tune, but I'm not well versed in Mercedes like I am with Ford.
When troubleshooting ANY complex system, it is always a good idea to configure the system from a known reference point. In this case, that would mean OEM parts and modules. If something ELSE is out of spec and you added an admittedly out of spec module, you may be taking a parameter so far out of spec that the ECU cannot compensate. This is NOT to say the larger TB is the problem, but that it is masking the problem.
I've been troubleshooting complex electronic communications systems since 1983, I've never used concensus to troubleshoot anything, and certainly not in the case where NONE OF US is there to look at what is going on - only YOU are standing there.
Do you want to fix this or not? If so, restore the car to factory and see what you have. Capturing live data with something like a CP123 or Bosch 1100 may also help lead you to the answer. That's all I have.