Occasional hesitation on slight acceleration when driving
 

Hi all,
Thanks to all on this site that have made owning my X5 more enjoyable. I hope someone will be able to give some advice on some occasional vibration I have been recently experiencing when slowly accelerating while driving slowly. I have had the vehicle minor serviced recently with no error codes present at the time of service. I notice that when the engine is warm and while in park, if I press the accelerator slightly and hold it the engine revs climbs and drops repeatedly about 200-300rpm. Though it may be due to a dirty MAF but when disconnected the engine does the same. Has anyone experienced this or know what could be causing this. Engine starts well when cold and accelerates good under heavier acceleration, fuel economy seems lower but may be due to me accelerating faster to avoid the slow acceleration vibrations. Is there anything I can try to see what may be causing this? My X is a 2003 4.4 Sport.

I hate to say it, but I had exactly the same problem when my transmission went bad ... vibration disappeared when I replaced the transmission ... but honestly I did not try the revving after I changed they tranny ..

I assume the vibration starts over 40km/hr when you are on the second gear and you start to accelrate slowly... right?

replace the torque converter.

i have a similar problem. it almost feels like its skipping. right?

^^

Yes I replaced that too with the tranny

A tranny replacement is a pretty penny... hopefully it could be something else?

Hi there,
I had my tranny rebuilt and the above described annoyance shifted down from 50km/h to 40km/h and reduced in quantities and strength,as well as the famous rear end Bang,some times it's downshifting that I can feel it did,but I got only one Bang in 3 month now.It happens only when Throttle Position is sending 0.5amps to the ECU,everything above that doesn't provoke it at all.
The tranny's module was re flashed and a part of the valve body was replaced along some solenoids.
From my own experience if you are about to get your tranny rebuilt,or do it yourself,like some people here or get it done by the dealership.
That shuddering never happens in S mode,so it should be some kind of software/hardware glitch,imo.
Also my tranny is loud between shifting at sub operative temps.
Almost forgot to write,it seems to act worse if my battery is weak.

Thanks Essam Khafagi, not really what I wanted to hear and had assumed it was more engine that tranny but now that you mentioned it it does sounds very similar to what I am experiencing after a bit of driving. As it's only occasional at the moment I a m hoping that there is some smaller repair other than a complete tranny replacement. Did they say exactly what was wrong with the transmission that causes the vibration? Anybody know if any fluid replacement would help?

My tranny got all the problems because the heat exchanger went bad and mixed tranny oil with radiator water ... check my thread at that time on this link http://www.xoutpost.com/bmw-sav-foru...n-rebuilt.html

I rebuilt it the first time then the heat exchanger went bad again! .. all the problems came back after like three months then I decided not to rebuild again .. I got a used tranny and replaced the whole thing.

johninoz2, did you replace the tranny and did it solve your pbm?
i have the same exact pbm....
at slow acceleratioms, some annoing hesitation appears. i changed the transmission oil, helped the 2nd to 1st rough change for a but but came back.
dont think ill find a 4.6is tranny replacement in Morocco .... i feel like ill stay without a car for months till i import one.

killcrap: will a memory reading pinpoint the pbm coming from torque converter vs the gear disks being used or will it just say that ive got a pbm somewhere in the gearbox and good luck finding it?