MicroSquirt.com read only forum (Jan.15,2018)

Dave
It nearly ran yesterday...but i am having problems with the tacho...it seems to be twice the actual reading

I lied...its not fixed.
i have a tacho pulse, but i only used one wire !
in megatune it says the engine is cranking, but in realtime it isnt cranking ?
i am using VR 1, i have connected the outer shield wire which gave me the tacho. this has been connected to the bikes original tacho wire.
what i cant work out is that i have a permanent live feed to both coils, but it appears that the trigger is a
+ve feed as well ?. surely this cant be right.
should i connect both of the vr wires ? will it do any damage if they are the wrong way round ?
also the bike appears to have a vr sensor which triggers the bikes igniter box, could i link in to this circuit ? without interfering with the signal.

if this fails there may be a new microsquirt for sale

regards gary

Yes, you should be able to run the stock VR sensor to both the igniter box and MicroSquirt. The uS input is high impedance, so it will not alter the signal that the igniter box needs. That should actually be the best way to sync uS and ignition, since the output from the igniter will be adjusted for advance, dwell, etc.

Use both the center conductor and shield for that connection, to ensure you have a clean trigger signal.

I would guess that you're saying you have a permanent live feed to both sides of both coils because you're reading 12V on both terminals relative to chassis. This is normal. The coils are charged when the igniter box pulls the switched terminal low, and fire when the igniter stops pulling the terminal low. When ignition is on, but the engine is not cranking/running, both terminals of each coil will read 12V relative to chassis ground.

Paul...
i think i have blown the microsquirt... i have not tried what you suggested yet.
any ideas what settings i will have to put in to the ignition...so it sees a engine revolution.

do you know anyone who wants a burnt out micro squirt...one careful owner

If you're only using the one VR input, the default settings should be correct already.

What makes you think uS is blown?

Paul
I had the tacho working yesterday...the one in megatune.
then it just stopped working.
if i use the vr input...do i tell it it has a 8-1 pick up ?

Yes. Set that under advance ignition options.

update...
i have connected the vr sensor...i have a tacho input.
buts its cranking at 1600. so i tried different settings in the advance part...the tacho stopped working

.
any ideas.....thanks gary

Post a picture of your crank trigger wheel and VR sensor, and also screen shots of what you had the ignition options set to when you were reading 1600 RPM cranking and what it was set to when it was not working.

Also, what is the actual cranking RPM (per the bike's tach)?

problem fixed.
it helps if you get someone else to look at what you have done.
even though i thought my tacho input was good...it wasnt !
negative side of the coil pack, one zener diode...and it runs ( thanks to newtyres )