Speed-o prob?

[hinchcliffe]

The needle in my mothers '89 325ix flickers. I'll be driving along at any speed and sometimes the needle just drops down about 10-15mph then imediately goes back to the current speed. Happens all of the time, therefore I can't use the cruise control. Any thoughts?

Also when in gear and stopped, it's an automatic, the rpms surge. Goes from about 500-800 rpms back and forth. When its in neutral it evens out at 600 ish. Any thoughts? Had new idle stabilizer valve, new muffler, thottle body seems nice, as does the MAF just past the airbox. Any thoughts on what to look for?

Curt
'89 325ix, moms winter car
'87 928S4 my summer car
'95+ 740il still looking for a nice one

[Unregistered]

well first problem is almost certain to be the speedo inpulse sensor on the back diff,

dodgy wires, or grime on the sensor

[Unregistered]

That exact thing happened on my BMW motorcycle, which probably has a similar if not identical sensor arrangement. Take it out and wipe it off with a clean rag, then replace. No more problems.

[hinchcliffe]

Where is the sensor? On top of the rear diff? SHould be easy to find?