Hi everyone,

I'm driving a '06 550i with 84k km on the clock. I've noticed lately that my engine sounds a bit weird above 4000 rpm. The noise from the engine is not constant when accelerating, but sounds like it's hesitating. The sound remains the same when I lift my foot off the throttle as well and the rpms are > 4000. The car feels like it's accelerating OK, I can't say I can notice any difference, but the sound is noticeable.

I've had my spark plugs replaced about 13k km ago along with tranny oil and motor oil + filters. Changed oil and filters again 500km ago, no difference.

Any ideas ? Could this be transmission related? It's an automatic.

 

Not understanding your description. It is hesitating but does not feel any different?

You are describing a concern about a sound about 4,000 rpm not a performance related issue correct?

 

Well.. yes. It is kind of hard to describe... The sound from the engine does not sound right when at high rpm. Instead of the constant sound of RPMs climbing, I get a feeling like the engine is hesitating, but the RPMs appear go up smoothly.

 

Try resetting transmission adaptation through INPA

 

Well, not really sure if that helped with the engine noise, time will tell. It's not really happening every time, so far I think it's been good. Another good thing is I got rid of a nasty "kick" when going from 2nd to 3rd. Apparently the 25s+ hold on the accelerator doesn't do anything, as I have tried that a few times.

Thanks for the advice

 

honestly, sounds like the transmission torque converter....google that problem and its symptoms.

 

Do you realize that you have a bi-modal exhaust that opens up the second exhaust tip around that RPM? Below that you are only using the left exhaust tip, and above, both exhausts. You may notice that both exhaust tips are not quite the same color. The left is probably mostly black while the right is mostly clean/chrome. You will hear a louder sound during the switchover along with a surge in torque, depending on the gear. More noticeable torque surge in gears 1 and 2.

 

Yes, I'm aware of the valve. The exhaust sounds more throaty when it's open, that's not my problem. I haven't felt any power loss when I notice the engine sounding different. So far I haven't noticed it since I've reset the transmission adaptation. I'll report back if I do, or if I find anything else.

 

try doing the adaptation reset through INPA if you have the cable and software. Its much better than the 25 sec trick. I did it last week.

 

@Blackwolffm Thanks, that's what I did. I don't think the 25s pedal thing actually does something, as I've tried it before.

@umichchris I thought that as well at first, but the torque converter issue usually appears as rpm fluctuating at steady speed, often when going uphill, which is not what's happening on my car. The RPMs do not appear to fluctuate, although the engine sound suggests that. I've watched the RPM needle as well as the hidden menu and the RPMs appear somewhat steady... I'm not ruling it out though. For now I'm going to wait and see if it happens again after the adaptation reset.