Teekay1983

Its a 2003 model 530i automatic. About 120000 miles.
Im experiencing fluctuating rpm on my m54 engine. When engine is cold the fluctuating never starts until the engine's been running for about 7 minutes. It dosent matter if the car is standing still or moving, the fluctuating still begins around 7 minutes. The rpm moves around 300 rpm and when turning up the climate control fan, I hear the blowing of air through the vents fluctuate at the same level as the rpm needle. It dosnt matter if the engine is idle, running at 40 or 70 mph. I also feel the engine braking and speeding when rpm is fluctuating which is normal when rpm moving.
This fluctuating only goes on for about 5 minutes each time, the car drive normally until the next time the engine is getting cold. Guess we're talking sensors?

seanjordan20

Is this car an automatic or manual? What model? What year? How many miles? These are things you should put in the initial post so everyone can get a better picture.

Once I see those I would say maybe: Have you checked to see is thier are any pending errors in the system. I would assume the MIL has not illuminated so I would hook it up to INPA and see if it telling you something. Has the spark plugs been changed lately? Have you recharged you a/c in the past week? Check to make sure your injectors are working properly. It could be alot of things but im leaning towards plugs since I have nothing to go off of.

Teekay1983

Updated first post with vehicle info.
Did go through and deleted the general errors in inpa, but i have not yet checked what errors have come back on after driving the car.
No changes to a/c system.
Spark plugs not changed by me since i bought the car six months ago.
But why would the spark plugs have anything to do with a fault that starts when the cars been driven for 7-10 minutes?
I would think something down the line of a combination of temprature and sensors.

To get the errors on the statustab in the engine menu of the inpa, do the engine need to be running?

Teekay1983

Sometimes when the fluctuating stops, the dynamic drive failure comes on so it may be related.

seanjordan20

No the engine does not need to be running just turn the key to the on position. I just took a stab in the dark. Try to see if there is a code coming up and we will go from there. It could be the mechtronic or a computer failure. There are too many things it could be without a code and you dont want to throw parts at it without isolation. If the dynamic drive failure comes on then their should be a code. Make sure you also check under transmission for codes. Do not forget to check both lists in the trans for errors

Teekay1983

I havent been able to pull the error codes yet since im away until friday. When driving a longer distance yesterday the rpm would start fluctuate every 20 minutes or so for a few minutes then back to normal, no dynamic drive errors this time. Until now the rpm only fluctuate once every drive.
Will see if the same happens on the drive home and pull the codes next weekend.