L293D outputs different in different motors. Are there different types of DC motors?
The L293 H bridge is a poor choice for a low supply voltage motor controller. From memory, at 1 amp load, the volt drop across the output transistors is about 1.8 volts and this means, from a 5 volt supply, you'll only see about 1.5 volt across the motor. You need to use a H bridge that utilizes MOSFETs as the output transistors and you will probably find that when you do, the motor current is more like 2 to 5 amps I.e. far in excess of what the L293 can supply.