engine fueling cold vs warm

[melmount]

I have been posing on a miss or a shake. My truck is a bit better with the way injectors seem to fire when cold after a minute warm up.
Is there a fueling difference? I know gas engines have closed and open loops.
I was wondering if injectors got more volts, or if extra fuel was given by the pcm at low rpm's when the motors cold to help it run better. I think I have a weak injector but it passes the traditional tests. Wondering if cold is getting more fuel from the pcm programming?
thx