Z4 35i bucked twice this morning...

[Tangent]

This morning right after a cold start my Z4 gave a quick buck twice (several seconds apart) when lightly accelerating in second gear. I don't have any long cranking when starting, but I do have what I think is a louder than usual whine from the fuel pump. I say "think" because even though it's noticeably louder than my E46, I also know the pump's likely a lot closer to me than in that car right? It is a bit of an odd uneven sound though, almost like morse code. It's been doing that since I bought the car 2 months ago and performance and starting has always been flawless until this morning. Am I looking at the HPFP failing or could this be something else?

[nicknaz]

DCT?

I had that once or twice too when car was cold. Have it in my M3 too on occasion. I wouldn't be too worried unless it is repeatable or worsening

Using the "manual" mode seems to eliminate the issue

[Tangent]

Nope, it's a manual. Hopefully it was just one of those of little hiccups modern cars have occasionally...

[Lurcher]

all else fails, reboot....

Seriously, remove battery cables for 30 minutes and reset

[Tangent]

Ha, yeah. "Hello, IT, have you tried turning it off and on again?" It did it once more this morning, but between my original post and now that's it.

[SpikeMilligan]

Instead of the fuel pump, it could also be a clogged fuel injector (damn ethanol fuel!). A bottle of injector cleaner in the gas tank may be able to clear it up if it's not too clogged.

I had similar hesitations, which later turned into long cranks, and eventually threw some misfire codes, so BMW replaced all the injectors. Thankfully under warranty.