A freind of mine in France has fitted a Zetec SE1700 in to his Panter Lima and is having problems getting the revcounter to work.

The engine management is the standard Ford.

The tacho is an old Jager with the looped white wire on the back, like the early MGB's had. One side of which went to the pos + side of the coil.

I'm guessing the issue is due to the wasted spark coil???

He knows ther is lots of knowledge on this forum but his English is not good enough to make the request himself.

Any advice will be gratefully received.

Its a common problem with fitting modern engine ignition to instruments from an old distributor car. You can use the following diagram to combine the two coil feeds from the wasted spark coil pack, to the tacho.


tachometer diodes

EDIT: I'm making the assumption that the instruments are off a 4 cylinder engine, so are looking for the correct number of pulses. If the guage is off a 6/8/12 cylinder car, you'll need to replace / modify the guage.

[Edited on 29/1/13 by deezee]

From memory - I think it is pin 48 a white and black wire on the 104 MUFF ECU that will give you a suitable pulse to drive the tachometer.

The old tachometers with the loop of wire are current sensing devices, the loop of wire is the same wire that provides the +12v ignition supply to the coil.

This type of tachometer almost never works correctly with modern high energy ignitions, and particularly wasted spark systems like the Zetec has. With the voltage sensing instruments you can combine the two wasted spark signals with the simple circuit shown above, but you can't do this with a current sensing tacho.

I suspect your only options are to find a similar style instrument with a voltage sensing input, or take apart the instrument you have and replace the movement and electronics with some from a more modern device, e.g. like this.


[Edited on 30/1/13 by MikeRJ]