big_ipaq

How much should be the normal idle speed for a 530i M54B30. I had some problems with Engine Oil Pressure Low (I explained in this thread).

The service dealer, recently increased my idle speed. I checked with the hidden menu and now it is always between 760-780 rpm. Problem is that engine is a little rough at this speed. I can feel him much more than before in the weel, not enough to be visually evident but enought to feel it more through my hand.

1. Is this idle speed normal?
2. What causes this vibration / rough running around 760-780 rpm?
3. Before, I think my engine was idling around 630-650 rpm and was running very smooth, except for the Engine Oil Pressure Low message. Was this idle speed to low? They said I've a lot of consumers in the car and they increased the idle speed just a tad, when the consumers are on (A/C, fan, etc).
4. Can I do something about?

THANKS A LOT.

big_ipaq

No ideeas?

dlevi67

This looked a bit forlorn, so I thought I'd give it a little bump and some encouragement.

My 535d idles at 680 (with a warm engine), so possibly the 630-650 was a little low. IIRC, my E36 325 was idling at ~700 (but it was 10 years ago!). Finally, judging from my E39 535, a 100 rpm jump with AC on is normal, and also it's normal that the engine is a little rougher at the higher speed - why I do not know.

big_ipaq

Maybe 700 rpm would be the best compromise. I just driven a E90 330i N52b30 and an E92 335i N54b30 and they were both idling at 630-680 rpm.

Thanks dlevi67!

katheikia

I just had my DMS re-tuned and now the car idles at 500rpm. This seems perfect! 06 550

dlevi67

erm, yeah, but a V8 will idle significantly lower than a I6...