Reduced power warning

[Draculaw]

I have an intermittent issue with my 2010 N18 Cooper S.

Symptom: intermittent reduced power warning in tacho on the digital speed readout. No EML in centre cluster. Goes away about 30s after switching car off, taking key out and starting again.

This seems to occur under heavy acceleration but only at two points on my commute - after going around a fairly wide roundabout and then onto a 70mph dual carriageway and after going up a wide sweeping slip road onto a 70mph dual carriageway. In both instances it generally triggers when hitting about 50mph/3,500 rpm in 4th. However, I have no issues doing that at other points on the commute.

Something I have noticed is that at 70mph (3,000 rpm/6th) there is a faint whine/whistle. It's hard to describe, but it'd say it sounds like the sound a weight would make if attached to a rope and swung around quickly, or an old school sci-fi alien spaceship. This doesn't seem to be present at 3,000 rpm in other gears.

My immediate thought is the HPFP. I had the valve seals replaced recently and the timing chain was checked and tensioner replaced, so confident it's not something related to that. Car has around 80k miles on the clock.

Any thoughts?

Edited by Draculaw on Friday 14th June 08:26

Edited by Draculaw on Friday 14th June 08:27

[E-bmw]

Are both instances right handers?

If so could be that the fuel pick up to the LPFP is on the right hand side & isn't sending enough fuel to the HPFP when below a certain fuel level.

[Draculaw]

Unfortunately not. Slip road is a long uphill left hander.