I built a mini quad, it seems like it doesnt have enough power to take off.
4 of these motors :
4 of these ECS's:
and a 360 mAh 7.2 volts LiPo for the meanwhole till I get a larger capacity pack.
I use a lightweight plastic frame, everything seems to work fine (props running the correct direction etc.)
and it seems as if it doesnt have enough juice, is the voltage too low for this setup?
Possibly. I have the same configuration, however use a 20C 800MaH. The problem may be the C rating of your battery.
The other issue I had was that I had to change the maximum PWM rate in the Multiwii code. The standard value was not high enough.