rpm gauge

[andy_hstad]

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

[AdamW]

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.

[SprinterTRD]

Unfortunately they are no longer available from MoTeC

[stevieturbo]

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

[AdamW]

http://www.autosportlabs.com/product/tach-adapter/
http://autometer.com/cat_accessoriesdetail.aspx?vid=99

[andy_hstad]

thanks for all quick replays.

what do you think about doing like this