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.
An engine misfire causes the power to drop and reduces gas mileage. It also increases the vehicle's emissions and can cause it to fail an emissions test. A severe misfire can cause the driver to feel a jerking action while driving.