Starting anoter thread in order to focus on one item at a time. Here is the link to the original thread which will provide background etc. Basically, it feels as though the fuel is being shut-off or a number of cylinders are down momentarily, as the car will jerk fairly hard under acceleration. This occurs most often when warming up and when accelerating from a stop with low engine speed. It also stumbles at idle and has thrown a 1216 (Throttle Potentiometer) code. When it stumbles, the CEL and parking brake light illuminte for a half-second.

So, I would like to furter investigate the potentiometer issue and am wondering if someone with an M50 could could test theres with a multimeter and record the results as per the dialogue below. Ryan R has kindly agreed
to send me a working potentiometer, but it will be in transit for a while.

This is the Bentley instruction for testing the potentiometer



As Bill G states below, he has his doubts abouty the Bentley procedure.

Anyhow, this is what we have deduced so far.........

Bill G
If you are talking about testing the throttle position sensor as per Bentleys page 130.8 - there is something wrong with Bentleys procedure. My wifes 1992 325i M50 has same sensor which is in good working order as far as I know - I measured voltages between harness connector terminals and body earth -
pin no 3 (top) 5v
pin no.2 5v
pin no. 1 6.5mV (this pin is earthed)

Also, voltage between terminals 1 and 3 5V.

Hope this helps.
Dave M

Now, when I tested all three harness pins to the strut (ground), I recorded the following (Note, my VDC was set at 20V, so I may be limited):

pin no 3 (top) negligible
pin no.2 5v
pin no. 1 negligible (this pin is earthed)

Does this mean anything to anyone?
Bill G
Seems like there is something wrong with pin 3 value.
According to the BMW Electrical Troubleshooting Manual (ETM), for Motronic 3.1 M50 -

Pin no 3 (top) connects to pin no 59 at the DME (or ECU as commonly called) and should have 5V
Pin no 2 connects to pin no 12 at DME and should have 5V - this is the pin which receives the varying voltage signal (approx range 0.4V to 4.2V depending on throttle position) back from the TPS

Pin no 1 (bottom) is earthed

My own results were measured at the removable harness, ignition on.
It would really help if someone else with a known good system could check and report their voltage values to back this up.

Bill G
As always, thanks for reading,

Dave M