I know this has been covered a bit in past threads but Looking to open up more discussion and thought on the subject of voltage drop/consumption with higher horsepower builds.

99 NB
efr turbo with flow force ls coils and 960 injectors.
dw200 fuel pump
Megasquirt ms3xpnp
stock alternator.
no stereo
no ps
no ac


pulls done with or without lights etc. does not seem to matter.

alternator putting out solid voltage (14.5v) during almost all driving conditions and has been tested at alternator and battery during idle with a multimeter.

Voltage drops pretty signifigantly under full load pulls. Like 11.5volts. As soon as I lift it jumps back up to the standard 14.5v.

im just curious as to thoughts on how the ecu/coils/injectors etc handles these voltage ranges and at what voltages people have noticed any issues.

I am a bit more skilled in line voltage items (day job as a commercial/industrial electrician) where it is common to keep voltage ranges within 2-4% on any of our technical equipment we power in that industry or we see circuit board issues.

11-14.5v is more fluctuation than I would prefer to see. obviously megasquirt can tune to compensate for this, but has anyone found a better work around to keep voltages more consistent?

i would assume this is just basically an acceptable side effect of a now underpowered/sized alternator based on the larger coils/injectors/fuel pump when dumping lots of fuel/spark during high boost/high rpm pulls?

any thoughts on how low of voltage an ecu/injectors/coils will properly operate at and thoughts on alleviating this? Or am I worried about nothing here?

 

Is your megasquirt set up to disable charging at "WOT" TPS valves?

 

I found a thread that may explain it. Options grayed out, but changed to 99% WOT TPS as thread states and changed WOT Target Voltage to 14. Then changed back to 101% WOT TPS. Going to try running this and see if it fixes the problem.

https://www.miataturbo.net/megasquir...ht-wot-100793/

 

Huh, more megasquirt bugs I didn't even know about. Interesting. Hope it fixes it for you.

 

To close this issue out, this fixed it. Hope it helps someone in the future.