I don't recall any problems starting the second engine on an A++, and I've started a lot of them, often on post-maintenance runups. The idle gate is an imaginary location, and can be set anywhere you like. I like it set on the low side of the specs, and I don't use it for the start. The flight manual calls for pressing the trigger before moving the throttle, and that's the way I do it. I go to the idle gate, more or less, by feel, and may sometimes move the throttle just a little one way or the other to get the desired results. It takes a few starts to get a feel for how much to move the throttle, but it's not really that difficult. Putting the throttle past the gate before pulling the trigger seems to me to be asking for an overtemp.
It may be that the problem is caused by the aircraft being upside down, along with everything else down there.
