Power balance testing is one of the best and easiest ways to find the source of a misfire. The idea is to isolate each cylinder to see if it’s producing the same amount of power. If you find a cylinder that’s down on power, it’s likely you’ve found your misfire. Once you’ve located the problem cylinder, you need to find the cause of the misfire. This can be tricky, but as I said at the beginning of this article, if you take a logical approach, you’ll be successful in your diagnosis.
More information about what to do when you find a misfire, and how to diagnose engine performance issues, can be found in the Solving Automotive Performance Issues article. For now, here’s a video on power balance testing.