Any experience of Megajolt ignition?

[Jono]

This relates to one of my other projects but I imagine the principles are no different with a Mini engine.

I have converted the Lotus twincam engine in my Elan to run wasted spark ignition - Ford EDIS, trigger wheel, coil pack, TPS, Megajolt etc.

I had my tachometer converted to RVC from RVI by Speedograph Richfield. The system works brilliantly but I'm bu66ered if I can obtain a suitable signal to drive the tacho. I have tried the suggested pins on the EDIS, inc pin 11, without success. I have tried the dedicated tacho output on the Megajolt - this gives nothing except for a big spike when I kill the engine which momentarily sends the needle around the dial and then back to zero.

I can see from the internet that this issue is not new - everyone seems to have issues getting the tach to work with this system.

I am a bit stumped with this one - are there any ignition wizards out there who can make suggestions? I've tried Speedograph but they can't seem offer any advice.

Cheers, hopefully.

Jon

[5portsrock]

Better of on the Turbo mini forum, lots of people use that system on there

[Smiffy]

Sounds like you need to use the diode trick, details on the autosports website.
Under: Interfacing to Tachometers

http://www.autosportlabs.net/MJLJ_V4_ve ... guidelines

[AndyB72]

My mate is running MJ on his Midget, here is what he had to say, hope it helps...

I used a tacho feed from the PIP out of the megajolt - just spliced into the wire.
My RVC tacho was converted to RVI, and this needed a +12v feed (which goes to one of the old bullet terminals), and then there was a new terminal which took the feed from the PIP.
I added an extra earth, didn't want to rely on earthing through the case.

[Jono]

Thanks for your comments/suggestion chaps.

I tried the diode driver without success.

I eventually traced the issue to a poor earth on the tachometer. Now running perfectly on the 'clean tach' output of the Megajolt.

Jon