1998 Subaru Forester Owner's Manual - Page 160
1998 Subaru Forester Manual
Page 160 highlights
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. 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 circumstances should the rear wheels be jacked off the ground, nor should the driveshaft be disconnected for I/M testing. 7-6