strange idle behaviour-automatic

[wernermeister]

I got a 1994 325i with auto transm. about 110Kmiles.
Here is the challenge:
if transmission is in "D", and I come to a stop, the idle keeps popping/moving between about 500rpm all the way up to 900-1000rpm up and down.
If I have it in "3" gear, it is rock steady at about 700rpm.

So, I started checking into this, and here is what is so strange:
if in "D", and I just touch the shift lever and push it ever so gently towards the "3" gear, it immediately goes steady to 700rpm; if I let go, it starts jumping again.

So, can somebody please explain how this can be (i.e. relationship of gear and idle); and more importantly, how do I fix this?
Is there an easy way to "adjust" that shift lever???

Appreciate your help!

[MADDOUG]

There is a gear lever selector switch underneath the gear lever surround that tells the ecu that controls the box what gear the car is in.

It is about 3 inches long and you will see it can be taken apart and cleaned but it is best to remove it and spray contact cleaner inside it.

It may be worn out or have had some clutter from inside the car fall in to it

[MADDOUG]

RealOEM.com * BMW E34 525tds Gear shift parts,automatic transmission


The parts drawing is for my car a 94 tds but yours will be the same or select yours on that link.

You have the switch and also the cable .

The cable can be adjusted although I have never done one.

Sounds like your engine management is getting the signal that the box is in neutral and drive off and on hence the rev jumping

[wernermeister]

Thanks Maddoug
next time we have a "dry" weekend to work on the car I will taggle this cable adjustment thingy.

Appreciate your help.