BMW e91 no start - head scratcher

So I have a weird starting issue with my 2011 E91 with the N52 engine. ( 328ix wagon, normally aspirated 3.0 l for those who don't speaker BMW codes). It won't start when it is below 10C outside. Four times now it won't start in the morning, but starts instantly in the afternoon after sitting in the sun for a few hours. It will crank quickly and for as long as I wish, but seems like it is getting no fuel. The battery is a few months old. The tank is full of gas. When it starts in the afternoon it runs great no stumbles or hesitations and I can turn it off and restart as much as I want.

Once when it didn't start, it threw a message for 4x4, ABS failure, limited performance, bring to BMW dealer for service. When it again started later that day the message was gone and says "all systems OK".

I am thinking it has a fuel pump module failure. Perhaps a bad electronic part that acts up when cold? I wouldn't think that a bad fuel pump would work intermittently like this? Weird.

Any ideas out there?

If you haven't pulled the codes with a proper BMW diagnostic computer (not generic OBD2), that's the first step.

Fuel pumps are pretty common failure on those.

Try putting your ear to the gas filler while someone cranks it over during one of the no-start occurrences. Listen for the buzz of the pump.

My 07 335i did this once, started up later that day with no problems. I would love to know what caused it as well.

Got an appointment with a indie garage on tuesday, it is supposed to be cold out.

Well, its the eccentric shaft sensor for the VANOS.

Apparently this little devil allows oil to seep past a weld into the guts of the sensor. It dies. It then allows oil to travel along the sensor harness to the DME to kill that too. About $2.5k in parts and 5-6 hours labour because the valve cover has to come off to change the sensor. Hopefully my harness and computer are OK and stay OK.

PSA - before buying an E90 pull the sensor plug and inspect it for oil accumulation. Also, if you ever need to fix a leaking valve cover, do it immediately and you may wish to replace this sensor as preventative maintenance. Better still, don't buy an E90 at all. There is Dorman part for about $250 that may be an upgrade vs. the OEM Seimens part which costs $650.

Before the no start problem, I had noticed a little bit of rough idle with a cold engine and slightly sluggish acceleration when cold. This was the car telling me it was unhappy with the sensor and VANOS was inoperative intermittently. Meanwhile the computer said everything "OK". It is like BMW designs failures to be as lucrative as possible.