Ignition Coil: Testing and Inspection

Ignition Coil Testing

When measuring KV on cylinders 1 and 2, remember that the voltage is flowing from the outer electrode to the center and back to the coil. This will be indicated by negative voltage readings on the oscilloscope. KV's on cylinders 1 and 2 will also be approximately 20% higher than on cylinders 3 and 4 as it takes more energy for the spark to travel from the outer to the center electrode.

Secondary output in the 7 - 9 KV range are normal during firing of the cylinder on the compression stroke and 3 - 5 KV for the cylinder on the wasted spark stroke. A defective coil will influence two cylinders, a defective plug wire only influences one cylinder.