Hi there,

I have a problem (last hurdle before MOT) in that with my alternator connected and charging, the engine cuts out when the alternator hits 14V. I'm running Megasquirt V3 with extra code, if that helps. I tried adjusting the dwell voltage correction settings and injector voltage correction but no joy. It's almost like its seeing an over voltage and cutting out.

I stuck the wide and on it, and the mixture leans out as it cuts out, whereas before, this wouldn't lean out until after the engine stopped. Could this be related to the additional load on the engine from the alternator charging resulting in a lean fuel map?

Any help or experience appreciated. Thanks.

Has got to be something to do with the battery voltage correction for the fueling. is the pulse width going right down as it nears 14v? do you need to extend your voltage correction table e.g. does it stop at 14v? are you running the latest code? if you are I would think about asking James on the ms3extra forum. make sure you post your msq up on there when you ask though.

I'd agree with Ash. Battery voltage correction may be out.
I've only seen it do that when the voltage drops though.

set battery correction to 0 and see what happens. It should get a little richer with higher volts, but not enough to cut out.

Thank you fellas, for your input. I tried resetting the battery correction to 0 but with no change. I'll try and extend the correction table when I get home (working away) and see how that goes. It makes sense, as the table goes up to 14V, as does The voltage when the engine stops.

Thanks guys, I'll keep you posted.

Are you certain it's voltage related, and not that you happen to hit 14v at a particular engine load or RPM?

Well, it revved freely before connecting the alternator which is why I asked if it could be load related. I'll try the voltage chart first as this does stop at 14V, making it the most likely cause for now. If that doesn't work, then I'll adjust the fuel bins to compensate for the additional load.

Thank you fellas, all sorted. The problem was because of the increase in voltage and load on the engine, I had to totally re- map the base map. I might try and get an MOT tomorrow!!