Today we had a FN2 in for diagnostics.
Engine was running very poor idle and fuel trims were -30%. All spark plug white (lean) except cylinder 3 (black / rich).
Customer already replaced allot of parts without any improvement.
After checking the basics I noticed that there was a wire running from the injector rail.
Apparently there was a alarm mounted on the car and it was interfering with the injector signal.
After removing the wire all was fine again.