Features:
1. To judge the quality of coil according to spark color and distance.
 2. The car factory choose the appropriate coil depends on engine and igition   system.

Application:
1. The normal spark distance is 2cm,and the shape is straight with violet blue color. The coil is aged or defect if the spark is either red or curved.
2. Spark plug in oil vapor that spark ignition cylinder, and also in combustion chamber with pressuring. Higher pressure would cause larger impedance of s park plug. In order to apply many kind of compression ratio of engine, adjust the distance of spark tester to simulate the state of cylinder is burning.