The OS type F plug is pretty hot , but I dont think that is your problem. I would guess you are running a low or
no nitro fuel. At that cold of a temp you may have to leave the ignitor on until the engine warms up.
At 32 degrees F which is 0 on Cel. I have to leave the hot shot on my ST .90 about 45 seconds. The engine
has to be warm to the touch or it will die if the throttle is advanced. You can also pre warm the engine a little.
Use a lighter or hot water from a thermos around the cylinder head to pre-heat. later daveo