My 2005 X3 (3.0 w/ automatic trans) experiences a bucking under acceleration at about 3000 rpm. It was REALLY bad until I replaced the upstream O2 sensors. That helped dramatically, but the problem still exists - to a much lesser extent, however. The vehicle has just over 120,000 miles on the odometer, so i would expect there would be other things to cause the surging and bucking. My thoughts are in fuel delivery (pump or filter) or possibly DISA valve or ignition coils. Sometimes it feels like starvation, but I have never had a code - even with O2 sensors, and they obviously needed replacement. Additionally, there has been a measurable decrease in fuel economy over the past several months. Any suggestions will be much appreciated.
Hey I had the SAME problem quite recently. I replaced the o2 sensors as I would get a code for first bank pre-cat. I then changed the coils/plugs which had over 100k on them anyway. NO DICE. While going uphill at exactly 3100 rpm the car would chug, It would feel like a miss. I read and read and read. Eventually I ran into a thread where a guy who tried and replaced every damn thing ended up RESETTING his adaptations with DIS V57 and it cleared up the problem. So I reset my adaptations with INPA and it STOPPED and the car was smooth going uphills again.
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