The car is a 2003 330i auto-
Have been experiencing a slight bucking under acceleration from around 75mph. this is not under hard acceleration just gradual acceleration- and it doesn't do this at lower speeds-
Has anyone had this problem, or similar?
What may cause this?

TIA-

Guess what...I have the same problem.

Only with my car, its under 75% load going from 2-3k rpm. The actual speed is really not a factor.

My mech (who will work on the car on Thursday) thinks its a lean condition...the bucking is the car recalibrating the A/F ratio.

I would look at O2 sensors and MAF sensor as the first culprits.

I had a code that didnt' throw the CEL: P0171 - Pending Lean Condition.

Get your codes checked...just because you don't have a CEL light on...doesn't mean there aren't any codes.

Guess what...I have the same problem.

Only with my car, its under 75% load going from 2-3k rpm. The actual speed is really not a factor.

My mech (who will work on the car on Thursday) thinks its a lean condition...the bucking is the car recalibrating the A/F ratio.

I would look at O2 sensors and MAF sensor as the first culprits.

I had a code that didnt' throw the CEL: P0171 - Pending Lean Condition.

Get your codes checked...just because you don't have a CEL light on...doesn't mean there aren't any codes.

thanks for the info-
I need to take the car in the 30k service, so I'll let them know to check for this

I'm having the same problem. My "check engine light" comes on for a little bit then goes off. I have 71k and it is mostly highway, I always thought it was the O2 senor acting up?

Your codes will tell you for sure...its probably an O2.

However, another member on this forum had a very similar problem and even though it threw no codes...it was the MAF.

I might have to cough up the $500 and just change out all the O2 sensors and the MAF...it would be good to ensure the car's continued reliability.

I don't know if this is meaningless or not, but my VR6 had some serious issues with leaning out, and cleaning out the MAF connector solved it, right before I was about to put a new one in. I doubt this happens often, but it's worth a try I guess.

You can bet that I will be cleaning mine tomorrow before I take it in to my mechanic.