I just took the X1 test for Exhaust Systems from ASE. Without giving away the content of the test, the Delmar Study Guide is a medium grade preparation book with shallow explanations.There are sections in the X1 ASE test that the Study Guide did not discuss. The subjects the Study Guide does discuss are repeated multiple times and are only good for engraining the content to memory from repetition of reading the same subject over and over. This same repetition however, tires the reader and gives a loss of interest in the book.
Explanations of Secondary AIR systems are incomplete. The Study Guide refers to the AIR Bypass Valve and the AIR Diverter Valve as one in the same. The Study Guide also advises that increasing exhaust pipe diameter 1/4" to 1/2" over stock is an acceptable modification to improve engine performance, which is true as this modification lowers exhaust backpressure, however the Study Guide neglects to inform the reader that this modification may increase spark knock as Positive Backpressure EGR valves require exhaust backpressure to open the EGR valve. There is also evidence of poor proof reading of the book by the author or publisher as the self-test example questions in section six have two sets of questions that are repeated word for word.
The self-test example questions in sections five and six do have their version of the correct answer for each question with an explanation as to why each possible answer (multiple choice) is correct or incorrect. I found this the most enjoyable reading, as some of their answers were incorrect to their own questions. For example, in one question, a catalytic converter is blue showing signs of overheating; this could be caused by rich fuel management, or a plugged fuel filter. Their answer was C for both are correct, and their reason why is that a rich condition provides excessive HC in the exhaust, which is true, and a plugged fuel filter would lean out the engine causing excessive HC in the exhaust, that is incorrect. A lean condition, if ignited, would have low HC, high O2 and high NOx, usually accompanied with spark knock. If the lean were greater, misfire would occur and would pump HC, or unburned fuel into the exhaust, which could overheat the catalytic converter. This was not explained in the Study Guide.
I wonder if the authors of this book have taken the X1 test themselves, and I doubt they were technicians.
Brad Piper, Auto Technician since 1995, Master ASE Auto & L1 Advanced Engine Performance ASE Certified.
