tachometer and starter pin

[speedrr]

I am bravely attempting the wire harness for a Motec M800 on my 88 BMW E30 m3. Since this is a street car, I need all of my instruments to function. To do this I have to rewire the C101 connector which is basically a 20 pin connector. I have it all figured out except for Pin 9 and Pin 18 on the C101. Pin 9 goes to the instrument panel for the tachometer. Pin 9 on the male side of C101 goes to the Motronic Pin 21 labled "Engine Speed Output". What pin on the Motec should this go to? Do I simply use an auxoutput such as Pin A34?

Pin 18 on the C101 male side is a 2.5mm wire that goes to the starter Pin 50 and is spliced into a .75mm wire going to the Motronic Pin 4 labled "Start Input" which is hot only on start with the ignition switch. Where would the .75 wire go on the Motec? Do I need an input signal to the Motec that is only triggered on the start portion of the ignition switch.

Thanks in advance!
Tom

[stevesingo]

Tom

I recognise you name from s14.net

You should wire one of the aux outputs to the pin 9 on the C101, then assign that aux output to tach on the motec software.

You shouldn't need the pin 18. I believe it is there to tell the motronic when the engine is cranking. Motec does not need this.

I'm planning on doing M800 with mine when I finish my restoration project. Are you planning CoP and sequential?

Steve

[RossB]

You can connect the tacho to an Auxiliary Output as you say (or an un-used Ignition or Injector Output on an M800) and configure the output as a Tacho Output.

There is no need to connect pin 50 to the M800. The Motronic uses this for cranking compensations but the M800 has a parameter in the Miscellaneous Setup called "Run RPM" to allow this functionality.

[speedrr]

Thanks Steve, thanks Ross! Steve, I recognize you too from S14. I know you have helped me in the past.
Tom

[speedrr]

Steve,
I am doing COPS and sequential injection. My COP setup will be identical to Anders.
Tom