I have a problem with my BMW 540iA E39 Built in 2001 ECE model, VIN 7 digits GG91066. 62 000 kilometers.
It is concerning the idle and the rpms from idle to about 2000.
The engine vibrates and you can feel as if the vibrations are from misfiring of the ignition coils. Although there is no fault in the car. All the adaptions were deleted and a reprogramming was made of the DME, but no success. I have checked each coil, by idle engine running and i was pulling each cord of the ignition coil to hear a difference, but all of the coils made the engine run much more rough. and i have noticed that this vibration is only between idle and 2000, so if it would be an ignition problem, it would be all around the rpm range. What was replaced was the EML idle system and new catalysator, new service inspection, new exhaust, mass air flow sensor is OK, a new one was tested, which made the same symtoms. I have tried to take the oil cap off, whilst the engine was running, and the situation of the motor was much worst, but the same vibrations occured, only in a larger amount. so maybe the engine is taking wrong air from the intake hose or whatever which might be causeing the problem. the PCV was not checked yet, thought of getting that checked next year, and what i also did was disconnect one of the two crank position sensors, and there was no sign of change, with or without the sensor in the plug, but if both of them are disconnected the car doesnt start.
I went to various dealers of BMW and all of them just hooked my car on the MoDic, which showed no error, and asked for a large amount of money, and said all is fine.
If i put the A/C on, the rpms lift from 500 to around 750, which is ok, but you can still feel the vibrations, and the funny thing is that the rpm needle is constant. so it is only that you can hear the exhaust, and the vibrations you can feel. my dad has a 530i, which runs really smooth, and i am very dissapointed that mine has these problems.
As i said the idle is really low, even sometimes a bit below 500 if the motor is really warm, and if i press on the gas pedal a bit, to raise the rpms to 1000, and let the gas pedal go, the rpms go very fast down to 350 and up to 750, and go down to 500. and sometimes the car even stalls when i do this.
The spark plugs are new, coils seem to be fine, no oil spills any where by the engine... i really do not know what it can be.
But otherwise the car runs great but the consumption is high, but i was mostly in the city, here in Hungary.
It can also be, maybe the Lambda sensors have a fault or I really have no idea anymore.
Merry christmas and a happy new year,