Introduction Auto Engine Performance and Driveability is designed to help you diagnose and repair the complex engines and computer control systems on modern vehicles. Most com- plaints related to engine performance result from problems caused by the failure of a sensor, output device, or compo- nent. Troubleshooting today’s vehicles takes complex test procedures, much service information, and elaborate test equipment. In addition, fuel economy and exhaust emis- sions must be closely controlled to meet federal and state guidelines. For you, the technician, knowledge is the key to servic- ing a vehicle. Reading is a necessity to absorb the informa- tion in manuals, troubleshooting charts, and schematics. Some basic knowledge of mathematics and electrical theory is necessary to understand the operation of computer con- trol systems and how those systems affect the vehicle. Experimentation and random parts changing can no longer be performed. Both are simply too time-consuming and expensive. You must be able to use service information, test equipment, and, most importantly, your reasoning and logic skills to find the cause of a problem. Simply being able to perform diagnostic tests is not enough. You must be able to evaluate the test results to determine what they mean. Chapters 12 and 13 provide you with a seven-step diagnos- tic process that will help you locate the cause of perfor- mance problems. This seven-step process can also be used in diagnosing any system, not just those that are automotive related. Once you learn this process, you will find it invalu- able in other automotive classes. Auto Engine Performance and Driveability has been written to help you develop those skills necessary to prop- erly diagnose and fix driveability problems. Each chapter of the textbook begins with learning objectives that provide focus for the chapter. A list of technical terms used in the chapter appears after the objectives. These terms are printed in bold italic type and are defined when first used. Society of Automotive Engineers (SAE J1930) standardized sensor and electronics terminology is used throughout the text. Each chapter concludes with a summary and review ques- tions. Additionally, the following features appear through- out the book. Note: A note may highlight important technical information, present information related to the topic, or cross-reference the material. Caution: A caution identifies a situation that may result in damage to the vehicle, tools, or equipment if the proper procedure is not followed. Warning: A warning identifies operations that have the potential for injury. One of the reasons you are reading this book is to pre- pare for ASE certification, which is important for any tech- nician. To help you in this area, ASE-type questions are included at the end of every chapter. Advanced ASE ques- tions are included in the advanced chapters. These ques- tions require reading schematics, referencing trouble codes, and analyzing data. These questions are similar to those found on the ASE Advanced Engine Performance (L1) test. One of the final chapters is devoted to a detailed 3