How to do a Power Balance Test

Start the engine and allow it to warm to normal operating temperature. Connect the tachometer as per directions for your particular vehicle. Disconnect one fuel injector momentarily and replace. This will require using a pick on most injectors to remove the small wire spring clip on the electrical plug attached to the injector.

Note the rpm drop on the tachometer when the injector is disconnected. If no tach is available, use the one in the car if one is available and have a helper call out the amount of drop when the injector is disconnected. There will also be a visual and sensory indication. You can hear the engine rpm drop and the engine will shake if the cylinder is working. It is not as accurate but does give the right indication. If you come across a cylinder than seems to cause no perceptible drop when the injector is removed, the cylinder is considered dead or not working. Make a note of its location on the block.

Spray some water on the exhaust manifold right where it makes contact with the cylinder head. Cylinders that are working properly produce and average of 450 degrees or better which will instantly evaporate the water. If the water coats the exhaust and is slow to evaporate, that cylinder is not firing.

Check the power balance on carbureted vehicles by using the insulated pliers and pulling one spark plug wire at a time out of the distributor cap and then replacing it. This gives the same indication. If you disconnect a wire and see no apparent drop in rpm, just follow the wire to the spark plug to identify the cylinder.