The document summarizes the four stroke engine cycle as intake, compression, power, and exhaust. It then provides more details on each step, such as the intake valve opening to allow the air-fuel mixture in during intake. It also lists the three vital systems for engine diagnosis as the fuel, compression, and ignition systems and provides examples of checks for each system like testing for gas in the tank under fuel system diagnosis.
![The Four Stroke Cycle ,[object Object],[object Object],[object Object],[object Object]](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)