MoTeC Global Forum

Hi I have a motec m4 where I do not have more outputs available and want to plug in the original tachometer in the car. The original tachometer was connected directly at the ignition coil but now I have 4 ignition coils connected in waste spark. can i hook up tachometer wire on ign 1 on motecet and get the rev counter to work?

Andreas

To drive a tacho from wasted spark coils you need to use a "ignition combiner" or sometimes called "tacho adaptor". Motec have them: http://www.motec.com.au/filedownload.ph ... docid=1203, you can find schematics online if you want to make one yourself, or available from companies like MSD also.

Unfortunately they are no longer available from MoTeC

You may find the tacho in the car has an adjustable pot inside it that will allow you to adjust the reading for the reduced number of pulses from a single coil.

Or you could perhaps feed the 4 ignition outputs into a 4 channel amp, then combine the amp outputs to run the tacho ?

That should keep the ecu outputs isolated from the combined trigger.

Or maybe something like this ?

http://jaycar.com.au/productView.asp?ID ... TID=965#11

thanks for all quick replays.

what do you think about doing like this