Proud new owner of a 2010 750Lix M-sport with a few concerns and questions

[Doenermann]

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Good evening everyone!

I have been somewhat active on e90 post in the past in regards to our 335i and my late x6. After a 4 month stint in C63 AMG, I'm happy to be back in a BMW - a 2010 750Li xdrive to be exact. The m-sport package is what sold me on this particular car at my local dealer, and I decided to take quite a financial hit and trade in my c63 after only a few months. More on the car later as I've noticed a few things which concern me about the car so far.

Let me begin by saying that the dealer claims there is nothing wrong with the car (big surprise there, in the fact the reason I sold my X6 back in November was that I couldn't put up with untreated problems anymore) but I'm not giving up easily this time.

My first concern is a noise, a "whine" to be more exact, which is very annoying at low RPMs when taking off at a light or driving at residential speeds. This noise can be heard from inside and outside the cabin. I've done my research on this forum and according to the dealer, it is NOT the oil pump others have had problems with - right. I uploaded a short video to Youtube which captures this noise fairly well, especially in the second half. While the title screen reads "cold start", it is infact a "cool" start - no cold revving here!

After finally getting an external microphone for my gopro and recording a fantastic video of the engine / turbo sound in the 335i, I was excited to try it on the N63 engine. I was shocked, yet amused by the resulting noises. At full throttle all is well, but please feel free to take a listen to it at lower speeds, video below.

Lastly (and no video of this unfortunately), the car vibrates quite a bit (felt in the steering wheel and butt region) when accelerating moderately but at low rpms in the 1400-2000 range. It feels like once boost builds up (without downshifting) it starts to vibrate and that disappears instantly when the foot is lifted off the gas. Likewise the vibration is also gone once RPMs go above 2000. This works very well in every gear at the according low speed (other than first of course), and dealer claims it's normal. Is does not appear to be a tire / wheel or road vibration as it only occurs when accelerating. No e90, e92, e70 or F10 loaner, our 335 or the previous x6 or any car I've driven every did this.

The tech at the local dealer actually said this in reponse to my conerns "well what do you expect, it's an upside down V8!"

In any case, I would appreciate any input you may have and I will try to add the car to the garage and post some pictures!

Regards,

Doenermann

[bruno787]

the whining noise could be caused by a defective belt pulley.

my 740 is due for a fix soon, and my previous benz also had this problem. seems common among the plastic pulleys being used nowadays on newer engines.

[Doenermann]

Originally Posted by bruno787

the whining noise could be caused by a defective belt pulley.

my 740 is due for a fix soon, and my previous benz also had this problem. seems common among the plastic pulleys being used nowadays on newer engines.

Thank you for your input. Sounds very plausible, but the question is how to get it fixed under warranty when "nothing is wrong with it". I just hope that this - along with the vibration gets much worse or goes away completely very soon.

[freshwhite335]

My parent's car has had the same whine since day one.

[Doenermann]

Originally Posted by freshwhite335

My parent's car has had the same whine since day one.

That's terrible news but thanks! With windows up and radio on its still quiet enough to deal with for now. I'll take it to the dealer again soon for this and also the vibration they claim is normal

[vladberca]

The vibrations at low rpms can be caused by the turbo lag, the engine is not in the proper torque range for (hard) accelerations.
Once you pass 2000 rpms the problem dissapear because you enter in the "torque band".
Hope you understood

[iBeech]

The shaking on wheel and butt is cases by badly aligned wheels- get the wheels aligned and that problem will go away

[Doenermann]

Thank you both for the input. the shop foreman actually told be that the engine would be in some sort of "fuel efficiency mode" under ~2000rpm and yes, the there is no shaking or vibration above 2000.

Regarding the wheel vibration / alignment, I've seen my fair share of wheel / tire problems and was pretty sure this isn't one as it is only noticeable when accelerating below 2000rpm and goes away instantly when the foot is taken off the gas. And that is true for any speed where the gearing allows it to be in that range, feels the same at 20-30 mph as it does at 55-50. Therefore I don't believe it is a wheel balance issue the the frequency should increase at higher speeds.

I'll bring it up with service again on my next visit and will have the tires checked as well (although the dealership just mounted them when they certified it as CPO in february). It's just very annoying...