Before pluging the N80 if you erased the codes in ECU 1 with the vehicle running, as soon the codes were deleted the idle became erratic and the P2279 code appeared immediately, now with the N80 plugged (so no air beign aspirated from there) if you do the same process the idle remain stable and nothing new appear in any ECU, I have to replace this valve and drive the vehicle a few miles.

 

No, the electrical harness is disconnected purposely to test it, the valve should be 100% close with no air passing either way, the gas cap has like a year I bought it new, the jeweled version.

 

@Johnny Hotspur GT Yes, fuel cap is tight, I replaced the damaged MAF harness, I replaced the EVAP solenoid, ordered a new PCV so I have both PCV valves genuine and new, all firewall lines are now made out of brass with new check valves on it. All four turbo solenoids on top of the transmission were relocated to a more accessible place and those new hoses smoke tested, no visible smoke leaks in any hose and still getting this god dammed P2279 code with rough idle.
I already checked the rear main seal and seems to be ok, no visible oil leaks and no change on idle if I spray brake cleaner to the weep hole at the bell housing so I can discard this...

I suspect the cause MAY BE the friking conical air pipe that goes from the turbo inlet to the MAF of the bank 1. I see a really small ammount of white smoke comming out where the pipe fits into the turbo elbow, almost imperceptible. The gasket is okay, but the bank 1 pipe seems to be bad designed, doesn't fit correctly, I don't know how to seal this properly, the other side fits perfect and theres no leaks.
¿Any idea how to seal this or what else I can check?

 

You will need to replace the green "O" ring at the base of the conical pipe to turbo connection. Removing the pipe from the turbo is fidgetty but doable.