The intake cycle is where the intake valves open ... you don’t need to test its compression. However, if you notice a reduction in performance, such as a lack of power or a drop in fuel economy ...

While browsing auto repair and maintenance tools at your local parts store, you've likely come across compression testers like the Orion Motor Tech 8-piece kit, which Amazon sells for $16.99.

The Atkinson cycle delays the intake valve’s closing until the piston has completed 20 to 30 percent of its upward travel on the compression stroke. As a result, some of the fresh charge is ...