Ch 51 Emission Control System

Positive Crankcase Ventalation (PCV) System

Emission control system that prevents the release of crankcase vapors to the atmosphere by channeling them to the intake manifold.

Electronic EGR System

Emission control system that uses vehicle sensors, the ECM, and a solenoid-operated exhaust gas recirculation valve to reduce NOx emissions.

Oxygen Sensors

Exhaust sensor that measures the oxygen content in an engines exhaust gases as a means of checking combustion efficiency.

Air Injection Pump

Low-pressure pump driven by an engine and used to force air into an exhaust manifold.

Electric Air Injection Pump

Low-pressure pump used to force air into an exhaust manifold.

Charcoal Canister

Metal/Plastic canister filled with activated charcoal, that absorbs fuel vapors.

Secondary Oxygen Sensor

Mounted behind the catalytic converter used to monitor catalytic converter operating efficiency.

Blowby

Oil vapors and other emissions that leak past piston rings into an engine crankcase or form in an engine bottom end from heating of oil.

Narrow band Oxygen Sensor

Oxygen sensor that can only measure combustion efficiency near stoichiometric.

Heated Oxygen Sensors

Oxygen sensor that contains a small heater element.

Zirconia Oxygen Sensors

Oxygen sensor that uses zirconia and platinum to produce a voltage output that represents oxygen content in exhaust gases.

Air Distribution Manifold

Part of the air injection system thatdirects a stream of air toward each engiine exhaust valve.

Primary Oxygen Sensor

Positioned before the catalytic converter and a close to the engine as possible, used to monitor the oxygen in the exhaust gases as it leaves the engine.

PCV Valve

Positive crankcase ventilation system flow control valve. It is mounted on the engine valve cover or intake manifold.

Oxygenated Gasoline

Reformulated gasoline containing additional oxygen sold in areas where ozone reduction is necessary.

Diesel Particulate Filter

Removes diesel particular matter or soot from exhaust gas of a diesel engine.

Rear O2 Sensor

Sensor, positioned after a primary oxygen sensor in an exhaust system, that primarily monitors a catalytic converter for proper operation. It is also called a secondary 02 sensor.

Front O2 Sensor

Sensor, positioned before the catalytic converter and as close to the engine as possible, used to monitor the oxygen in the exhaust gases as it leaves the engine. It is also referred to as the primary O2 sensor.

Particulates

Solid particle of soot and other substances that results from combustion.

Closed PCV System

Type of PCV system that uses a sealed oil filler cap, a sealed oil dipstick, ventilation hoses, and either a PCV valve or a flow restrictor to keep engine blowby from entering the atmosphere.

Single-Stage EGR Valve

Type of electronic EGR valve that uses only one solenoid and valve to open its exhaust passages.

Planar Zirconia Oxygen Sensors

Type of oxygen sensor in which the zirconia element, electrodes, and heater are combined in a flat, laminated strip. Reduces contamination and vibration.

Aspirator Valves

Type of valve that allows air or liquid flow in only one direction, opening and closing based on pressure pulses.

Oxides Of Nitrogen (NOx)

Undesirable compounds of nitrogen and oxygen in exhaust gases. They are usually produced when combustion temperatures are excessively high.

Smog

Used to describe air pollution caused by chemical fumes and smoke.

Emission Control System

Used to reduce the amount of harmful substances emitted into the atmosphere by a vehicle.

Computerized Emissions Control System

Uses various engines, exhaust, and fuel system sensors, a three-way catalytic converter, and a dual-bank O2 sensor to reduce pollution levels emitted from vehicle.

Liquid-Vapor Separator

Valve above the main fuel tank used to keep liquid fuel from entering the EVAP systems.

Diverter Valve

Valve that prevents air from entering the exhaust system during deceleration.

Electronic EGR Valve

Valve that uses one or more electric solenoids to open and close its exhaust passages. It works without engine vacuum.

Fuel Vapors

Various chemicals that enter the air as fuel evaporates.

Mini Catalytic Converter

Very small converter placed close to an engine exhaust manifold.

Thermostatic Air Cleaner System

system for heating cold air before it enter the engine for better combustion

Rollover Valve

valve in the fuel tank or delivery line that prevent the escape of raw fuel in the event of a vehicle rollover

Two Way Catalytic Converter

A catalytic converter capable of reducing amounts of HC and CO from the exhaust gases.

Three Way Catalytic Converter

A catalytic converter capable of reducing amounts of HC, CO, and NOx from exhaust gases.

Dual-Bed Catalytic Converter

A catalytic converter that has two separate catalyst units ( a reduction and a oxidation converter) enclosed in a single housing.

Air Dome

A hump formed in the top of the fuel tank as part of the vehicle EVAP system to allow for fuel expansion and tank filling without spillage.

EGR Duty Cycle

A measurement of control current on and off time sent from the ECM to meter just the right amount of exhaust gases needed to reduce NOx emissions.

Air Injection System

A method of reducing hydrocarbons and carbon monoxide emissions by forcing fresh air into the exhaust ports of the engine by means of an air pump. It is also called an Air Injection Reaction System

Pulse Air System

A system forcing fresh air into the exhaust ports of an engine by using the pressure pulses in the exhaust system to operate check valves.

Carbon Monoxide

A toxic byproduct of partial burning of fuel. It is a deadly colorless, odorless gas.

EGR Solenoid Valves

A valve that uses an electronic solenoid to to block or pass airflow to an EGR valve.

Air Cleaner Carbon Element

Air filter that may be used to absorb fuel vapors when an engine is turned off.

Catalytic Converter

An emissions control device that uses the elements platinum, palladium, and rhodium as catalysts to reduce harmful exhaust emissions.

Evaporative Emissions Control (EVAP) System

An emissions controlled system designed to prevent vapor from escaping into the atmosphere.

Wide-Band Oxygen Sensor

An oxygen sensor that can change it's output gradually and in direct proportion to the oxygen content of exhaust gases.

Titiania Oxygen Sensor

An oxygen sensor that uses a thick film of titiania to detect the amount of oxygen present in exhaust gases.

Catalyst

Any substance that speeds a chemical reaction without itself being changed.

Motor Vehicle Emissions

Burned and unburned pollutant produced by car, truck, bus, and motorcycle engines and their fuel systems.

Stoichiometric Fuel Mixture

Chemically correct air-fuel mixture. (14.7 parts air to 1 part fuel)

Purge Line

Connecting lines for the Purge Valve

Oil Air separator

Device that makes oil vapors condense and flow back into an oil pan.

Electric PCV Valve

ECM controlled valve that regulates engine crankcase ventilation.

Exhaust Gasses

Harmful chemical or fume produced from the combustion of hydrocarbon based fuels (or most other fuels) within an engine.

Hydrocarbons

Highly flammable chemical mixture of about 12% hydrocarbons and 82% carbon that makes up that majority of crude oil.

Exhaust Gas Recircilation (EGR) System

Injects burned exhaust gases into the engine intake manifold to lower combustion temperature and reduce NOx pollution.