Erratic acceleration hesitation/delay

[AdeOzzyT]

Weird Power hesitation/delay X30d X3 F25 2012

Hi everyone, This is my first post. From last 2 months I have a problem with my X3 30d F25 2012 with 77000 on the clock. Car is behaving very weirdly and the moment nobody can tell what is going on with it and I can't find anything online. Suspicions are that this is a Transfer case or transmission but nobody tell at the moment. I will try to describe as best as I can. Car have a kinda of power hesitation or delay. It is happening most of the times but not all the time. No problems with start or idle at all. For example: Driving at any speed between 30-70miles/h on around 2000 revs trying to accelerate dynamically but what car does first is kinda dropping revs to let's say 1700 like car would decided to change gear to higher(today once did even down to 1500) and then the revs are going back up. Or for example there is a hesitation in general and most of the times whenever I want to accelerate fast from lower revs for example going on 1000 revs and press acceleration hard then car is moving but not much faster untill will hit turbo range and then pulling as it should. But this thing can happen on the higher revs too.  I have been to BMW specialsists to BMW dealer, automatic transmission place and to the guy who does transfer cases only too. Car doesn't really make any suspicious noises.  Things on the car done up to date.
1. EGR valve replaced (thrown code at BMW specialists and after replacing no more codes)
2. Change 4 tyres to Pirelli P Zero. For few weeks I was running on the rear with one new budget tyre and one P Zero with around 4mm tread) And 2 same new budget on the front. I have staggered wheels.
3. Changed fluid in the transfer case and reseted transmission.
4. Cleaned MAF
No change at all. Next not too expensive step (Spent £1400 already) would it be doing transmission updates.

Please follow the link to see video with the symptoms of  revs dropping. You can see it twice starting at 11sec that after acceleration the revs are dropping from 1500 to about 1200 to go up again. 
https://1drv.ms/v/s!AlD-rEy1Em_lj0M0CoMdfEy9a-Fj 

Appreciate any advices or suggestions guys
Thank you

[Horizon]

http://www.bmwforums.info/bmw-x-series- ... olved.html

X3's are very tyre savvy. You should have * marked tyre if running a staggered setup. Just a thought

[AdeOzzyT]

[quote="Horizon"]
http://www.bmwforums.info/bmw-x-series- ... olved.html

X3's are very tyre savvy. You should have * marked tyre if running a staggered setup. Just a thought

[AdeOzzyT]

Today I found with Carly for BMW error code 260F00 'throttle position sensor signal short circuit to positive'
Does anyone knows guys what it exactly means? Is my throttle body faulty? Sensor is attached permanently on this model I think
Thanks

[MattX]

I'm quite new to this F generation having come from an E46 but as soon as I saw this thread the first thing I thought of was your accelerator pedal.
If I was a betting man I'd say it's knackered and sending false signals. If it's anything like the E46 it's not too hard to change either.

[AdeOzzyT]

Thanks for the reply buddy.
I wish that this could be so simple as you are saying. How to check if the pedal is the case?

The thing is that this problem is not as bad on higher revs and and I haven't observed any revs dropping when accelerating over around 2500 rpm.
Also the throttle position sensor fault has gone now but one fault that is always coming back is:

'Integrated Chassis Module / Längs+Querdynamik
:Ldm function High Level Operational readiness Icm'
Code: 4827BA
I can't find anything online about this.

I have sent the faults report to BMW dealer and that's their answer:

'Them fault codes are for the ICM (integrated chassis management), which is basically airbag systems etc.

There will be no electrical fault stored for this vehicle relating to the fault. The fault is caused by a mechanical defect inside the transfer box. This is causing it to engage and disengage the x-drive system incorrectly. There is no other rectification procedure for that vehicle, other than complete transfer box replacement.'

Since day one they were saying that this is transfer case that is causimg a problems.

I'm a bit lost now to be honest. I want to try to pull 'transfer case' fuse out to see as this will change anything while driving on RWD only. I'm not sure which fuse is it.

If I could get proper diagnose regarding the transfer case I can get it repleced quite cheap with reconditioned one.