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

I've got some wierdness I'm trying to track down in the charger, and wanted to see if anyone here had any suggestions... Basically, the car is on a megasquirt V3 board, running MSnS-E 29q2, input direct from a locked MSD distributor VR sensor into the V3 board VR circuit. The output is driving an MSD-6A box with the circuit from the MSnS-E page. I've got the car actually running pretty well, but it has about 5* either way jitter in the timing. I've got the input trigger at 5*, If I set fixed angle output at 15*, it will jitter between 10* and 20*. RPM doesn't seem to make much difference. I know the distributor isn't the problem, because if I feed the 6A box the direct distributor VR signal, it is DEAD on (I can't see any jitter at all). Also, the tach signal seems very clean; it doesn't show any RPM spikes or wierdness...

Any idea what could cause this? I'm guessing maybe it's something in the VR circuit, but I don't understand how it could be inconsistent, but still hit every single time, you know?

Also, I know the polarity is correct because when I connect to the 6A box through the MSD harness (the harness is polarized), it fires at exactly 5*, as expected.

Any ideas? I'm still searching periodically, but haven't found anything

I don't have the same setup, but on mine the timing gets jumpy if I am not using the Last Algorithum (sp?) predictor.

that's only on ms2...

Try turning the VR sensor conditioner potentiometers on the V3 board all the way counter-clockwise.

May be off base here, but any chance the reluctor has the polarity reversed going into the MS??? Perhaps if you switched the wires around it would make a difference?
Tom