[mluckham]

Thanks very much, I'll test it. I made an additional change, to save the calculated values:

// set values for math-less calibration method
unsigned long tmptankdistance = tank.distance(); // take a snapshot, in case update occurs during the updates
unsigned long tmptankfuel = tank.fuel();
int tmpdirty = 0;

parms[calibrationDistanceIdx] = tmptankdistance; // distance x 1000, for updating parms[vssPulsesPerDistanceUnitIdx]
parms[calibrationFuelIdx] = tmptankfuel; // fuel x 1000, for updating parms[microSecondsPerFuelUnitIdx]

initGuino(); // edit parms[] array

// math-less calibration method:
// if user has altered distance or fuel values to be different from tank, recalculate VSS and INJECTOR parameters
if (parms[calibrationDistanceIdx] != tmptankdistance)
{
parms[vssPulsesPerDistanceUnitIdx] = recalculate(parms[vssPulsesPerDistanceUnitIdx], tmptankdistance, parms[calibrationDistanceIdx]);
tmpdirty = 1;
}

if (parms[calibrationFuelIdx] != tmptankfuel)
{
parms[microSecondsPerFuelUnitIdx] = recalculate(parms[microSecondsPerFuelUnitIdx], tmptankfuel, parms[calibrationFuelIdx]);
tmpdirty = 1;
}

if (tmpdirty)
save(); // save recalculated settings