Voltage spikes on 4AGE

[Vertigo]

Im on my third alternator trying to fix this issue. Randomly my alternator will begin putting out 16-17V, the sudden spike of which will reset my Megasquirt CPU, killing the engine until key is cycled. There isnt anything special about my wiring, though it is custom so of course I could have cocked something up here. The main +ve cable goes straight to the battery terminal, and the sense wire goes to the starter motor +ve cable, to take advantage of its low resistance. Standard SLIG connector. The only thing I can think of is that the IG wire is fed from the main relay, so constantly energized.

Any ideas?

[h4nd]

I'd suggest not putting the sense at the end of the starter cable, there could be some goodly spikes, because while it's low resistance, any inductance there on the large starting currents could result in a healthy back EMF. You'd need an oscilloscope to diagnose if that's the case. Probably better to put the sense wire close to the battery?

[kpr]

yeh try run the sense wire directly back to battery on its own wire. see what it does

[Vertigo]

Im wondering if the power wiring has intermittent resistance, causing the sense wire to see a voltage drop and tell the alternator to work harder. Running a new wire to the terminal would help the problem, but not solve the actual cause, if this were the case. There are a few spots which Id like to redo anyway with proper crimping, such as large gauge splices.

[gibbon]

Heat soak on the starter terminal wire perhaps?