Outer Limits 4x4 Board

Hi all,

My 1VD into 100 conversion is almost there, got it running yesterday.

Next prob is the tacho. My 100 had a 1Hz, which I believe gets a tacho pulse from the injector pump (although someone posted in another thread that it gets signal from the alternator??), but not sure what the pulse is (ie: 1 per rev or 1 per injection, or??). The 1VD sends a pulse to the tacho via the ECU, but again not sure how regular the pulse is. I have been told that it's most likely the same pulse as the V8 petrol.

So, assuming the 1VD pulse is the same as the V8 petrol, does anyone know if the pulse system is the same between the 1Hz and the V8 (ie: is it + or - pulse? Voltage?) and what is the regularity of both?

Spoke to an instrument specialist who had no idea of the specific vehicles, but does have pulse converter boxes that can adapt up to 99% difference and they are stackable (ie 2 in line for 198%)

I can't use the 1VD's tacho (different scale) and I'd rather not go to all the trouble of trying to put a petrol 100's tacho in there if I can help it. My ideal solution is the converter box, but it won't be any good if the 1Hz sends a pulse for every #1cyl inject (ie RPM/2) and the 1VD sends one for every inject (ie RPMx4).

i would think the only way to tell would be to compare the 2 signal on an oscilloscope.
The 4.5 will most likely use a 5V or 12V square wave signal from the ECU, No idea what frequency though

The 1HZ i think uses a sine wave signal from a sensor in the injector pump, once again no idea what frequency.

You will most likely require the signal frequency converter to get the pulse per rev correct, But you may also need a signal amplifier, or a digital to analogue converter.

I think there is gonna be a bit of trial and error involved. Maybe get someone to check the 4.5 signal with a scope, And then get the instrument guys to make the tacho work from that.

Steve