revs

[peter farago]

hello there,
why do the revs drop when the drivers door is shut on a 95'bmw 318is???

[Jeron]

Does it drop just for a moment or does it drop and stay low?

My guess is it is a voltage drain or short. If it is, then it is the alternator sucking power from the engine causing the rpm drop.

[peter farago]

Thank you for your replay..
The revs drop only for a moment and then go back up.
this also happens when the headlights are turned on and when i wind the windows all the way up.
So you think that i should change the alternator?

[Jeron]

Does your car have frameless windows that drop and raise when the doors are opened and shut?

The RPMs drop on my M3 due to headlights and windows.

I wouldnt change anything unless the RPM drop is a problem.

You might check and clean the connections at the battery and the alternator.

[peter farago]

Thanks alot for your help.
yes i do have frameless windows. ok ill give the connections a clean.
Once again thank you very much.

[Jeron]

Sounds like the revs drop due to the window roll up when the door is shut. If it is too extreme then the window travel may need to be adjusted. I think the procedure is to hold the button UP for 10 seconds but you should check to be sure. We have discussed it in the E36 forum, I think blkongry had the answer.

I think there is nothing wrong and the small RPM drop is normal.

[dboyles]

Sorry if I'm pointing out the obvious, but I'd try lowering the windows (so they won't go up/down when the door is opened/closed) and then closing the door to see if the RPMs drop. I think Jeron has properly diagnosed the problem, but I'd do this just to confirm.