The M50 series of engines (m50 / m52 / s50 / s52) seem to have used a number of different sensor configurations over the years. This can make it somewhat complicated when configuring VEMS.
I got alittle ahead of myself, and ordered VEMS configured differently then the sensors on my car.
I was under the impression that my car had two vr sensors, one for crank and one for cam. This may infact be the case in older m50 style engines. My engine however had a hall sensor (i think) for the crank mounted at the rear of the engine near the flywheel and another style sensor for the cam.
i was under the impression the cam sensor was hall after examining it.. but found a reference to it on a MoTec sight where they think it might be some sort of current sensor. Basically the solution is to swap it out, but i don't want to go with VR. I'd rather have hall - but my VEMS is configured for VR as the second trigger.
Here is a note from the MoTec site on the cam sensor
Cam Sensor we know wont work DANGER DANGER
BMW 1 703 221 Siemens 5WK9 6011
Sensor resistance, 12.2 Ohms between Term 1 and 2
.5 ohms between Term 2 and 3
12.7 ohms between Term 1 and 3
Any sensor which matches this resistance scheme cannot be used by MoTeC
We know for sure this sensor when used as a mag, requires Magnets to
produce any voltage a/c between 1 and 2 with 1 being the falling edge.
The answer is to pick a different sensor.
Cam Sensor which we know works
BMW 12 14 1 438 081 - Hall Effect Falling Edge
To solve the crank issue, i installed a VR sensor in the mounting location at the front of the engine. I'm getting a nice signal out of it, but VEMS does not seem to be picking it up. Gotta check into this more.
Questions:
I have a nice signal from my VR sensor, which has been verified with a scope. No noise,etc. I would estimate a 7 volt signal at cranking. No trigger events were being seen in VEMS. So i traced the signel across the board. It appears as though i'm having an issue with the output of U11 LM1815. The signal is only coming out at .6 volts and is a square pulse down to .3 volts (while cranking). If i place the primary VR sensor onto U12 LM1815, i get a nice 5 volt square wave and get trigger events into the AVR (i jumpered the output to the primary input of the AVR)
It appears as though i don't have the VCC pullup on the 10k resister which is connected to pin 12 of the LM1815. I can't seem to trace this back to where the issue might be?
Any help would be great. I'm banging my head here. Thanks!