Burn time seems to be a term that many do not understand. I used it in my Vacuum gauge topic and it has brought up a lot of discussion. It is simply the length of time that the fuel in the cylinder burns as measured by a scope or engine analyzer. The longer the burn the less efficient the cylinder is performing, usually caused by low compression. With today’s cramped engine compartments it helps to narrow down a problem cylinder rather than do a compression test on all cylinders. I think more techs are using a leak down test on problem cylinders as this provides more information than a compression test. If I had my vehicle in a shop and they wanted to do an outdated wet and dry compression test I would consider going elsewhere, sure it works but there are tests that will provide more accurate info. Many shops are at $100 an hour so any time saving tool they use is saving money. I do think that many of these new tools and test equipment that are necessary to work on the modern vehicle is slowly moving the DIY out and forcing them to go to a shop. More on this later.