The power of the Saab spark plug is the force behind the explosion in your combustion chambers. This is the only device on your car that intentionally creates an arc of electricity across an open space. There are two places on a spark plug on your Saab where an arc is created. The most obvious is at the end of the plug that is placed in the combustion chamber. The second arc is never seen by any one because it occurs inside of the hollow ceramic chamber that connects the two ends of the spark plug. The different situations that prevent the arc from occurring are what should be avoided so your engine will operate as it is intended to. The probe at the end of the Saab spark plug that the external arc goes to is the ground. This ground is solidly connected by the plug being firmly screwed into the engine block. If the spark plug is cross threaded for any reason a good ground will not be possible and the arc, if one is created, will be diminished in its power. This will not be able to ignite all of the air and fuel mixture in the combustion chamber causing the Saab engine to not have the ability to perform as expected. The ceramic chamber on the spark plug also has to be totally intact. If the plug is dropped or comes in contact with a hard object, a crack can be created. If this occurs for any reason, the plug will not be capable of creating an arc at the end in the combustion chamber and your Saab engine will be running on one fewer cylinder. Both situations have to be avoided for your engine to perform.