Well mine does now appear to be a faulty gauge or the map sensor for the gauge.

I connected the gauge up to a booster pack AND the car supply, started the engine and the gauge stayed on. I then disconnected the booster pack and went for a drive. The gauge is still over reading by at least 8 psi.

So mine is nothing to do with it calibrating whilst cranking.

I hope you sort your stack Lozi!!!