Digital Multimeter/Tachometer - How to connect to dizziless system?

[Tiny Tim]

I saw what looked like quite a useful tool in Maplin today. A digital multimeter with a tachometer function. Looking at the instructions it said to connect the meter to the battery (-ve) and the LT connection on the coil. However I have a dizziless system with a wasted spark coil so I was wondering if it would still be possible to use this by connecting to the ECU output to the coil? (thought it might be useful to have a digital read out when trying to set up the carbs). Any ideas?

 

It also had a temperature input and was only £9.99. here

 

Seven Goes Mad in Dorset

 

 

 

Edited by - tiny tim on 22 May 2006 19:04:02

 

Edited by - tiny tim on 22 May 2006 19:06:58

[Big Brother]

As you run wasted spark you will need to get a signal from both sides of the coil.

This can be done by tapping into each of the trigger wires and then using a diode on each wire.

The two signals can then be used to trigger your tacho.

 

See the bottom of the page here for a diagram

This example uses a third (zener) doide but my guess is you will be fine with just the two standard diodes.

 

Steve

 

 

SE7EN-UP!

The difference between ignorance and apathy? I don't know, and I couldn't care less!

 

[Manxseven]

Tim,

 

Post amended.

Cheers,

Simon

 

Caterham Fireblade here

 

Edited by - Manxseven on 22 May 2006 19:11:54

[Tiny Tim]

Thanks Simon,

 

Think I've got it now 😳

 

Tim

 

Seven Goes Mad in Dorset

[Chris W]

Connect one lead to ground and the other to the tacho input (you can scrape off a tiny piece of insulation from the tacho lead to get a connection). The reading you get will be your actual rpm x 2 because you have a wasted spark system. My multimeter has the same functionality and it works for me.

 

Chris

 

2003 1.8K SV 140hp see it here

[oilyhands]

Quite often the power supply to the coilpack is a single one so if the connection is inductive then you can connect to the supply...

 

Oily