MSefi.com read only forum (Jan.15,2018)

I'm running MSII PcB V3 with BG Firmware 2.862 and Ford EDIS ignition control. This is all in my 1976 BMW 2002 with an M10 2L 4 cylinder.

I soldered my tach interface to this diagram:


I used 1N4004 diodes on the pottom and a 1N4742 zener diode at the top. The tach worked for a while, but went dead when it reached 3000 RPM or above. Now it's not working at all. Any suggestions? I've heard of using a resister somewhere in the circuit, but I don't know where.

Any ideas? What am I doing wrong?

Thanks in advance.

Lance,
I tried the IDM terminal first, but no luck. What size resistor would I use?

Thanks!

Any updates on this issue? I'm trying to build the same circuit, and any time I add the second coil my tach dies. One coil reads 1/3 rpm fine.