WOW Killcrap, great info - thanks!
Yes, 3.0i
All started with a check light telling me "tank Ventilation solenoid" bad AND a message that bank 2 post cat O2 was not heating properly. I replaced tank vent solenoid AND as milage maintenance replaced all O2 sensors. (makes sense I made them more sensitive).

"a faulty engine wiring harness can cause lean/rich mixture faults, but will show transmission failsafe/ dsc messages also" - I DO NOT GET THAT MESSAGE.

"or have not reset adaptations" - HOW DO YOU RESET THEM??

I cleaned my air mass sensor (many times)
I smoked my intake, no signs. Used harbor freight pump - pumped cigar smoke into intake then blew into the hose (with my mouth) to force pressure, but I don't think I pushed it beyond the intake (should I have opened the throttle - pressed the pedal??). The intake held smoke pressure (my finger on the tube after blowing into it) and I saw no smoke leaks.

Swapped injectors/spark plugs/coils from bank 1 to bank 2 - ERROR DID NOT MIGRATE, ALWAYS BANK 2

"faulty valve cover. There is probably a crack between cylinders 4-6. This can be confirmed with a smoke test" - HOW DO I SMOKE THIS? I replaced Valve cover gasket 40k miles ago- oil leak.

My DISA "O" ring is not original, seems tight and no smoke
cleaned up and verified the idler control valve (got it rotating very easy)
Did a compression test, all 6 cylinders very close in range of 200-205 PSI.
Replaced my CCV system 20K miles ago. "test the crankcase ventilation system for proper operation" - HOW DO YOU TEST IT?

I need to do my homework and check the additives valves, I had found them once, saw that bank 2 were different but have since forgot how to get back to those valves. I use BMW DIS on my laptop.

software in the engine computer is faulty and should be updated. There is a bulletin that describes this situation - MY CAR DOES NOT FALL INTO THE AFFECTED YEARS

THANK YOU VERY MUCH!

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2004, X5, 3.0, 202k+