2009 Acura MDX Owner's Manual - Page 465

Main Menu Table Of Contents Emissions Controls Onboard Refueling Vapor Recovery The onboard refueling vapor recovery (ORVR) system captures the fuel vapors during refueling. The vapors are adsorbed in a canister filled with activated carbon. While driving, the fuel vapors are drawn into the engine and burned off. Exhaust Emissions Controls The exhaust emissions controls include four systems: PGM-FI, ignition timing control, exhaust gas recirculation, and three way catalytic converter. These four systems work together to control the engine's combustion and minimize the amount of HC, CO, and NOx that come out the tailpipe. The exhaust emissions control systems are separate from the crankcase and evaporative emissions control systems. PGM-FI System Three Way Catalytic Converter The PGM-FI system uses sequential multiport fuel injection.It has three subsystems: air intake, engine control, and fuel control. The powertrain control module (PCM) 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 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 (CO2), nitrogen (N2), 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 Acura replacement parts or their equivalent for repairs. Using lower quality parts may increase the emissions from your vehicle. The emissions control systems are covered by warranties separate from the rest of your vehicle. Read your warranty manual for more information. This system constantly adjusts the ignition timing, reducing the amount of HC, CO, and NOx produced. Exhaust Gas Recirculation (EGR) System Technical Inf ormation The exhaust gas recirculation (EGR) system takes some of the exhaust gas and routes it back into the intake manifold. Adding exhaust gas to the air/fuel mixture reduces the amount of NOx produced when the fuel is burned. 2009 MDX 461