1998 Subaru Impreza Owner's Manual - Page 165
1998 Subaru Impreza Manual
Page 165 highlights
State emission testing (U.S. only) WARNING Testing of an all-wheel drive vehicle must NEVER be performed on a single two-wheel dynamometer. Attempting to do so will result in uncontrolled vehicle movement and may cause an accident or injuries to persons nearby. CAUTION Resultant vehicle damage due to improper testing is not covered under the SUBARU Limited Warranty and is the responsibility of the State I/M Program or its contractors or licensees. The 1990 Clean Air Act Amendments require the Environmental Protection Agency (EPA) to implement programs to reduce air pollution from motor vehicles. States are required to adopt either a "basic" or "enhanced" vehicle Inspection/Maintenance (I/M) Program depending on the severity of their air pollution problem. The "enhanced" I/M test simulates actual driving conditions on a dynamometer and permits more accurate measurement of tailpipe emissions than the "basic" I/M test which measures emissions only during engine operating conditions at idle and 2,500 RPM with no engine load. The "enhanced" I/M test also includes a pressure check to identify evaporative emissions leaks in the fuel system. The U.S. EPA has EXEMPTED SUBARU Full-Time All-Wheel Drive (AWD) vehicles from the following performance warranty short tests: D Loaded Test D Idle Test With Loaded Preconditioning State I/M Programs should test affected SUBARU AWD models using any other EPA-91 approved performance warranty short test. SUBARU models equipped with the AWD feature should be tested on a four-wheel drive dynamometer or the State I/M Program may elect to use a "double two-wheel dynamometer" arrangement. Under no circum- 7-6