RPM Indication

RPM Indication

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Discussion

John042

Original Poster:

900 posts

184 months

Yesterday (08:54)
quotequote all
Help please? After Megasquirt Tuner finished making a pigs ear of remapping my ECU I now have no vehicle rpm indication. I have checked for loose plugs etc around ECU wiring, nothing obvious. Found a small box marked "Tachco" with a green light on it?? Is it possible the Tuner has somehow disabled the supply to the vehicle rpm gauge? Or have got a wiring fault? Thanks for any advice.

Wedg1e

26,924 posts

280 months

Yesterday (16:53)
quotequote all
The issue is probably down to where the tacho takes its trigger pulses from.
On the V8 there were two options I think, one senses the negative going pulses from the ignition amplifier to coil (-) and the other had a diferent design of tacho that was connected in series with the coil supply and detected the spikes caused by the coil firing.
I would imagine that the Megasquirt has some form of pulses output to drive the tacho but how compatible that would be with the wedge instruments I have no idea.