1994 Honda Civic Owner's Manual - Page 190

Emissions Controls Exhaust Emission Controls The exhaust emission controls include three systems: PGM-FI, Ignition Timing Control, and Three-Way Catalytic Converter. These three systems work together to control the engine's combustion and minimize the amount of HC, CO, and NOx that comes out the tailpipe. The exhaust emission control systems are separate from the crankcase and evaporative emission control systems. PGM-FI System The PGM-FI System uses a sequential multiport fuel injection. It has three sub-systems: Air Intake, Engine Control, and Fuel Control. The Engine Control Module (ECM) uses various sensors to determine how much air is going into the engine. It then controls how much fuel to inject under all operating conditions. Ignition Timing Control System This system constantly adjusts the ignition timing, reducing the amount of HC, CO and NOx produced. Three-Way Catalytic Converter The Three-Way Catalytic Converter is in the exhaust system. Through chemical reactions, it converts HC, CO, and NOx in the engine's exhaust to carbon dioxide (CO 2 ), dinitrogen (N 2 ), and water vapor. Replacement Parts The emissions control systems are designed and certified to work together in reducing emissions to levels that comply with the Clean Air Act. To make sure the emissions remain low, you should use only new Genuine Honda replacement parts or their equivalent for repairs. Using lower quality parts may increase the emissions from your car. The emissions control systems are covered by warranties separate from the rest of your car. Read your warranty manual for more information. Technical Information