Failing throttle actuators are quite common on the S85,so here is a DIY.
I am NOT liable if you screw up your car or health in any way following this DIY!
It is necessary to carry out initializing of the new throttle motor using DIS or ISTA after the replacement.
I also removed the micro filters and the panels for easier access to the back of the air boxes(it is possible to remove the vacuum lines without removing the panels,but it is easier when they are removed).
Then remove the air filter boxes(open the clamps on the air filter boxes,disconnect the MAFs and open the clamps of the pipes going into the air boxes)
Then disconnect the hoses on the back sides of the air boxes,the breather hoses on the sides and the hoses for the idle air in the front.
Use a flexible screw driver with a 6mm socket to open the clamps that attach the air boxes to the throttle bodies and remove the air boxes.
Cover butterflies with a cloth to protect debris falling in them.
Remove the bolt in the front and nut in the rear that hold the wiring loom down(tightening torque 10NM)
In the pic above the two vacuum hoses connecting to the air boxes are also visible.
Next is removing the plus wire coming from the jump starting point on bank1 as well as the second plus wire on the terminal(plasitc nut,see pic below,17mm socket,25NM tightening torque) and the cover of the ionic current unit on bank 2(10mm socket,tightening torque 10NM).
Also remove the bolt for the wiring loom(see pic below,10mm socket,tightening torque 10 NM)
Next disconnect the two plugs on the bank2 wiring loom side(mark then to connect the right ones again)
Disconnect also the bank 1 connector
Disconnect the throttle linkage of the actuator you replace(pry gently with a screw driver between linkage and ball pin of actuator) and remove the electrical connector.
The actuator has 3 bolts that attach it to the engine(10mm socket,tightening torque 10NM).
By moving the wiring loom carefully,it is possible to remove the bolts.
It is a bit tricky to remove and install the new actuator as it is very tight between the throttle bodies and the wiring loom.
But being careful,it is possible without breaking anything.
Assemble in opposite order to removing.
I usually leave the air filter boxes and air boxes away when initializing the new actuator.
This way also it is possible to see if everything works.
After everything is done,get yourself a beer and call it a day.
I would estimate it takes about 3-4h for the first timer.