Vehicle Overview:

1989 BMW e30 with a M50b25 NV out of a 91 BMW 525

More info here:,1983.0.html

specs on VEMS:

1 x Assembled v3.6 controller

- 1-wire interface: no

- withSDcard: removable

- PS2 connection: no

- secondary_trigger: HALL Need to convert to VR!

- mounting-style: no-screws

- MAP connection: 400kPa (5/3mm pneumatic)

- LCD connection: no

- EGT input: 1

- Flyback: 30V flyback

- ignition driver: 8

- Knock input channels: 2

- primary_trigger: EC36/27 VR

VEMS was purchased for a later M50 with Hall. This engine has a VR/VR trigger setup. to extend coil life and prevent IGBT's from over heating a cam sync will need to be installed. After following directions on this page:

Added blob to SJ7.



removed blob between SOT23 NPN base and collector



Directions to follow: I'm still trying to figure the rest of this out.

solder the 2nd LM1815 (same orientation as first: pin1 closest to atmega)

wire from EC18pin12 to the 2nd LM1815 input pad (that goes through a 18k resistor to pin3 of the second LM1815)◦ 1k pulldown resistor between VR input signal and GND

◦ this is effectively in parallel with the VR sensor. Scratch the green solderprotect a bit at the GND so an SMD resistor can be soldered

To make it work with the 1k VR-input pulldown resistor, connect LM1815 pin5 to +5V with the SJ4 (3pin jumper): solder the mid-pin to the +5V pin that goes LM1815pin8

R182=0 resistor (or short) at LM1815pin7. This helps the adaptive hysteresis (quicker charge). Has the same function as R181 >= 100k for the first LM1815 (soldered in factory) but 0 Ohm (short) is more appropriate here.◦ optionally increasing the neighboring 220nF capacitor by adding an additional (solder piggyback) +1uF or +2.2uF might be a good idea


i've ordered 2 lm1815 chips. I'll update this page one the chips come in.