have a 2000 s4 with hitachi maf and 01.5 ecu

car runs great just did k04 and running eurodyne maestro sottware

this problem we have had even with the stock ecu and any ecu we have tried. the problem is the fuel trims and codes to not stay stored in the ecu after key if turned off.

for example if we get any codes and fuel trim adaptation which works normal whatever has stored is immediately gone once the key is off and the car is turned on again. this has been a huge pain with tuning and any kind of troubleshooting. all readiness modules are reset and everything once key is off.

what should i be looking into to fix this. perhaps there are 12v constant wires keeping ecu memory alive but i always thought capacitors inside the ecu did this. or maybe a ground wuire that could be shorting after key is off i have no idea. any help would be appreciated.

I will try the Ecu in my car. As I recall no Ecu we have ever had in it stored codes or fuel trims. Eurodyne said it could be the keep alive which was pin 62 I beleive. Car runs awesome otherwise. Also I've never taken an Ecu out of a car for a long time and still had it keep data stored