Last month we briefly discussed the value of vacuum waveforms and explained how to adjust your scope to view them. This month we will discuss the effects an engine can have on the vacuum waveform. Vacuum waveforms are not easy to interpret, but once you understand the concept and have confidence in your abilities, you will find yourself using them more often than you would expect. As with any new procedure, the value is based on how fast it can help you find a problem. Your speed will depend greatly on how well you understand these waveforms.