At the OP mileage I suspect that you guys have a combination of carbon buildup on the intake valves and some injector clogging. I have owned 3 N54 engines so I am somewhat of an armchair expert on this motor. I suggest you guys do the following:
Originally Posted by Blubaron79
I just had an injector replaced last week. Now mine is also hesitating between 2500 and 3500 rpm under highway load acceleration. It won't do it in 1st or second gear when I'm pulling out.
1) Fill up with Shell 93 octane or Chevron 93 octane
2) Buy 4 bottles of BMW fuel system cleaner plus (just wait and let me finish)
3) At the first fill up do this: a) put a bottle of fuel system cleaner plus in before filling up the car b) warm up the engine at low RPM and speeds for 20 minutes c) take car onto the interstate and do 70 mph in 3rd gear making sure you are turning at least 4k RPM. d) Do the drive for 30 minutes and then shift to 6th and let the car cool down.
4) Two times a week for the next two-four weeks repeat number three making sure that you are running Shell or Chevron and using a bottle of fuel system cleaner in each tankful until all 4 bottles are gone.
I can almost guarantee your hesitation problems will be gone before or by the time all of the fuel system cleaner plus is used up. Once you have corrected the problem maintain the engine by doing my suggestion once a month. This is how I kept my N54's running good.....
Last edited by Alpine300ZHP; 01-03-2012 at 01:47 PM.