S52 OBD1 Crank Position sensor

[hammslice]

I am working on converting an S52 to OBD1 to go in my E30 325is. The motor I obtained has a light weight underdrive pulley and consequently has no toothed gear on the front of the motor for the OBD1 to get an RPM reading. My question is, do I need to get a stock pulley or can I use the OBD2 crank position sensor towards the back of the motor by splicing the connectors from the different harnesses?

I have the bentley manual and i was looking at the diagrams for the M50 and S52 and I wasn't sure if the sensors work the same way or which colors to match up.

Anyone out there done it this way or have some advice? TIA.

Also, if anyone has detailed pics of the wiring harness installed, that would be greatly appreciated as the harness I bought didn't have all of the connections labeled and I don't want to miss something.

[FredK]

The S52 has a Hall sensor for the rear mounted crank position sensor. The OBD-I Bosch 413 DME requires a VR signal to sense crankshaft rotational speed.

There is a converter board you can use:

http://www.seattlecircuit.com/hall_to_vr.html

Or you can get a stock front pulley and M50/S50US timing case-mounted crank position sensor.

[hammslice]

Thanks! I don't pretend to be an electrical engineer but I can read the diagrams well enough to see that something didn't look the same about the two. I think I will try out the link you posted so I can keep my lightweight pulley.

[Eecen]

Pretty sure Hoveringuy (the guy who makes that chip) just discovered that the m44 crank sensor works in the rear position on the s52 AND is a VR sensor this may be the solution you are looking for.

[hoveringuy]

Pretty sure Hoveringuy (the guy who makes that chip) just discovered that the m44 crank sensor works in the rear position on the s52 AND is a VR sensor this may be the solution you are looking for.

Yeah, I used the Hall board for the longest time and it works fine, but then I got a tip that the M44 sensor is a plug-n-play VR sensor that fits in that rear hole.

As much as I like electronics I would go with the native VR signal.. I've had the M44 sensor for a while and it works titties.

No wheel!

When you finish you can buy my FUEL CORRECTION CIRCUIT (shameless plug).

[samiam3356]

Awesome info