Help! 530i engine random stumbling no codes and humming sound
In the last 400 miles i had 250 miles with no issues, then this morning leaving the car didn't want to go, ran pretty rough (no codes or cel). Went away after 5 mins. Then tonight driving fine for 40 mins, then 3 mins of rough running when accelerating. Cruising is fine, just acceleration is rough and car does not want to go. Could it be the Disa valve? Im at a loss with this now, the no codes does not help.
On a side note the car is making a weird sound that almost sounds like the horn but very faitly. It does it almost all the time, at idle, driving, etc. Its not coming from under the hood but almost seems to be coming from under the rear of the car some where.
Any help would be great. Side note, the car has 168,000 on it. Picked it up at 165 a couple months ago from a friend. Missed my old e39 had to get another!