Long term lean running

[scrwright]

Getting the above code on my 03 9-5 aero. Also getting the boost being dropped over 2k revs with more than 1/2 throttle. Tech 2 is showing knock detection across all cylinders when it starts dropping the boost.
All intake pipes are new, as is brake vacuum pipe & servo. Not done much on turbo engines so what causes lean running on an engine running posative inlet pressure? Could it be the turbo overboosting? I would have thought the ecu would measure the MAP an fuel accordingly? Could it be a fueling (lack of) issue.

Engine is recently serviced with the correct aero plugs and always run on super.

Thanks

[scrwright]

New DI and the same boost/chattering issue. Plus side is the lean running code has cleared since changing the brake servo. Off for a run out with the tech 2 plugged in to see whats going on now.

[scrwright]

Just fitted a new Maptune recirc valve and all whistling noise has gone, getting a little chatter noise at WOT & higher revs, is that normal or is my turbo still over boosting?