Definition of quantal. 1  1 [Latin quanti how many, plural of quantus] : of, relating to, or having only two experimental alternatives (such as dead or alive, all or none) 2  2 [quantum] : of or relating to a quantum.
3. Engine movement. Another symptom of bad or failing engine mounts is an engine that moves in the engine bay. If the engine mounts are in good condition, they should be able to secure the engine firmly in the engine bay.
Additionally, if the parasitic load placed on the engine is higher than the command to overcome it, the engine will stall (the parasitic load could be such things as the power steering, air conditioning, charging system, torque convert clutch, etc.)