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Hi there everyone, I'm in New Zealand and it's a holiday weekend here so no help from the BMW dealer. My 745i suddenly started running very rough and it feels like it has a timing issue (lumpy idle and lumpy in the power band). It is also running very rich. Any clues where to start looking, like maybe an o2 sendor or something????:cry::mad:
 

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02 sensors could do that and/or ignition coils, Im not a tech bit that's all i could think of
 

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did you recently fill gas up in your 7? if so, the problem could be bad gas.
 

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The word for the day (or for this thread) is VALVETRONIC.

If the rough idle occurs after engine has reached normal operating temperature and there are no other driveability issues and no faults stored in DME fault memory, it may be due to insufficient VALVETRONIC adaptations.It's neccessary to check the calibration of the eccentric shafts and display the calibration angle. If the calibration angle is not within specification, it will then be adjusted and it should improve the idle quality.

If the problem of erratic engine idle speed lasting for approximately 20 seconds after a cold start and Check Engine Soon light may be illuminated and misfire faults for various cylinders (e.g. FC 2742, 2743, 2744, 2745, 2746, 2748, 2749, 274E) may be stored in the DME, the cause could possibly be incorrect tolerances and geometry of Valvetronic intermediate levers. Intermediate levers are causing uneven cylinder filling during the transitional cold start period (60 seconds after the engine has been started) when the Valvetronic system is switching from the initial 6 mm to a minimum 0.3/0.8 mm valve lift.

Either way a dealership expert should be able to diagnose and repair either condition and you should have your car back in less than a week if the intermediate levers needs to be replaced.The first day to diagnose and order parts,teardown,replacement,resecuring the engine compartment,and final checks including quality control should take no more than 3 days.It's not an easy thing to do,I must admit that I don't like this job because Im tedious and precise that I would spend more than what the job pays under warranty.I always put in what a customer would pay to do the job plus an hour to make sure it's driven and restarted plus inspected for any leaks or abnormalities.That's just me and that's why I don't like it.
 
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