When an engine misfires when accelerating or when the throttle is squeezed, it is not only harmful to the engine but also to everyone on the road. Misfires can happen when a vehicle is loaded and speeding. This causes your car to accelerate slowly or sluggishly, and it may struggle to do so. You may notice a jerking sensation when you press down on the throttle. The most common reason for an engine misfire when accelerating is worn-out spark plugs. Excessive wear on spark plugs hinders them from properly igniting the gasoline in the piston cylinder. This can be caused by faulty spark plugs, a broken distributor cap, or faulty spark plug wires. All of these problems have the same result: the coil voltage does not jump the space between the spark plugs, causing the engine to misfire as the car accelerates.