In this paper, a comparison between the past and the present in the diagnosis of the engines is made, starting with a brief historical review of the classic diagnosis of engines, common failures in some of its systems, and details of the diagnoses of the alternative engines, as background and contrast with the current modern techniques that are based on the analysis of the information provided by the on-board diagnostic tools and the signals of the sensor of the power train. This work seeks to update and extend the view on the practice of automotive diagnosis. To illustrate the use of those modern procedures, especially for service technicians, some operating parameters of a vehicle's engine are recorded for a test city driving tour, for later graphs and analysis of some operation maps and vehicle dynamics behaviors that can be obtained through the information obtained by the On-Board Diagnostics II system (OBD II).