E91 318i Valvetronic issues?

[orinoco13]

Trying to sort out my lads car. All was fine and then oil leak developed onto the exhaust, so changed the valve cover gasket and did the vac pump o-rings at the same time. Re-assembled and found the car wouldn't rev properly and was very slow responding to throttle input and wouldn't rev past 2 or 3k revs. Changed the Valvetronic sensor, put it back together and it started up fine and revved properly again. We then drained some of the coolant out to replace for the winter and started to vent the system with the car running and the not revving problem occurred again. Does anyone know if there is any likely or common culprit which would cause this issue? Trying to keep costs down on this as he's just on apprentice wages.

[d_a_n1979]

Have you read the codes to see what's stored/what they point to?

[orinoco13]

Yeah, initially we got 2 codes up for the valvetronic sensor, and there was a bit of oil residue in the plug so changed it out. This time we haven't had a chance to clear the codes and take for a run to check. Will do that tonight after work though. Cheers.

[I-am-the-reverend]

When refitting the cam cover, it's very easy to dislocate the spring/lever on the back of the eccentric shaft. That then causes all kinds of valvetronic problems.

As well as removing the scuttle trim panel it's also worth removing the rearmost bulkhead panel, a few 7 or 8 mm bolts.