Exhaust emissions 1
Driveability 2
Durability 3
Performance 4
Table 1
Device categories | Characteristics adversely affected |
Fuel-Air System | |
Carburetors and fuel injection systems | All. |
Air-fuel ratio modifiers (e.g., air bleeds) | All. |
Atomization devices (acoustic and mechanical) | All. |
Vapor Injectors | All. |
Choke controls | 1, 2, and 4. |
Air filters | 1, 2, and 4. |
Fuel-air distribution systems (intake manifolds) | 1, 2, and 4. |
Fuel pressure regulators | All. |
Ignition System | |
Spark plugs | All. |
Spark timing control systems | All. |
Spark duration control systems | 1, 4. |
Spark energy sources | 1, 4. |
Emission Control Systems | |
Exhaust gas recirculation (EGR) systems | All. |
After-treatment devices | 1, 2, and 4. |
Drivetrain | |
Tires | 1. |
Overdrive units | All. |
Torque converter lockups | 1, 2, and 4. |
Exhaust System | |
Headers | 1. |
Tuned exhaust systems | 1. |
Accessories | |
Cooling fan or cooling fan couplings | 1. |
Cold start aids (e.g., engine heaters) | 1. |
Lubrication | |
Oil filters | 3. |
Vehicle Body | |
Aerodynamic drag reduction devices | 1. |
Miscellaneous | |
Modification to valve timing | All. |
Retrofit prechambers | All. |
Fuel additives | All. |
Other miscellaneous | Potentially all. |
40 C.F.R. §610.21