Master23

To see the original article with images check it out here: Honda Civic Emission Systems: egr, evap and pcv. Garage411.com

EXHAUST GAS RECIRCULATION (EGR) SYSTEM

EGR system reduces oxides of nitrogen (NOX) emissions by recirculating exhaust gases through EGR valve into intake manifold and back to combustion chambers. System is composed of EGR valve, Constant Vacuum Control (CVC) valve and EGR control solenoid valve. EGR control solenoid valve is controlled by ECM, which analyzes input signals from EGR valve lift sensor and various sensors to provide optimum EGR flow. EGR flow is cut when combustion gas temperatures are low (when the engine emits a relatively low NOX emission) to ensure good colddriveability.

EGR Valve
When opened, EGR valve circulates exhaust gas through intake manifold and back into combustion chamber to be reburned, resulting in reduced combustion chamber temperature. Lower temperature reduces oxides of nitrogen (NOX) and helps to control spark knock.

EGR Control Solenoid Valve
When ECM determines it is necessary to recirculate exhaust gases, it grounds EGR control solenoid valve, regulating vacuum controlling EGR valve. By regulating vacuum to EGR valve, EGR flow is adjusted for optimum control of NOX emission.

Exhaust Gas Recirculation Valve Lift Sensor
The EGR valve lift sensor detects EGR valve lift and sends information to ECM. The ECM uses this information, along with other sensor inputs, to determine regulation of EGR control solenoid valve.

EVAPORATIVE EMISSION SYSTEM (EVAP)

Evaporative emission system minimizes fuel vapor escaping into atmosphere. For emission control applications and components used for each model and engine.

Charcoal Canister
Charcoal canister temporarily stores fuel vapor until it can be purged, drawn into engine and burned in combustion chamber.

Fuel Tank Vapor Control System
Fuel tank vapor control system consists of a fuel cut-off valve, liquid/vapor separator, a 2-way valve and fuel filler cap. All fuel vapor inside fuel tank is directed to charcoal canister through fuel cut-off valve and liquid/vapor separator.

Fuel cut-off valve and liquid/vapor separator prohibit liquid fuel from entering 2-way valve. When fuel vapor pressure in fuel tank is greater than set value of 2-way valve, valve opens and regulates flow of fuel vapor into canister. The 2-way valve regulates both pressure and vacuum in tank. The filler cap contains a relief valve to prevent excessive pressure or vacuum build-up.

Vapor Purge Control System
The vapor purge control system controls when charcoal canister is to be purged. Canister purging is accomplished when ECM activates purge control cut-off solenoid valve, allowing fresh air to be drawn through bottom of charcoal canister and into a port on throttle body.

POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM

The Positive Crankcase Ventilation (PCV) system is designed to prevent blow-by gases (in engine crankcase) from escaping into atmosphere. The PCV valve contains a spring-loaded plunger. When engine starts, plunger in PCV valve is lifted in proportion to intake manifold vacuum, and blow-by gas is drawn directly into intake manifold.

To see the original article with images check it out here: Honda Civic Emission Systems: egr, evap and pcv. Garage411.com

MarkEaston

I am a new-B here and looking for a EGR Control Solenoid or really the EGR Control box for a 92-95 Civic VX. Do you have any leads on how to find one? It seems there is a waiting period that doesn't let me search parts for sale.

Thanx

bleedblue94

might be a stupid question, but does the egr essentially replace the evap system? aka is it one orr the other, or would both be used on a motor like an h22 and such?

Former User

The EGR and EVAP systems are completely different animals. The EVAP system reduces gasoline vapor release into the atmosphere whereas the EGR system reduces NOx emissions.

bleedblue94

yeah i understand that part of it, the question wasnt based on them actually doing the same exact thing, it was more based on does each one kinda fullfill hondas emissions quest in its own way? like having two roads to gett to the same place. i just havent seen or know of a car that used both systems, and was curious if that was actually the case, or if any where using both systems...

Former User

The EVAP and EGR systems are similar only in that they both reduce emissions. But there are many different types of emissions, and these two systems control different types, with the EVAP system reducing hydrocarbons and the EGR system reducing nitrogen oxides. The 96-00 Civic HX has both an EGR and EVAP system. There are additional systems that also work to reduce these same emissions, for example the catalytic converter.

smokincoop

I think you may be a little off here. Almost every car/truck (gas. burner) I can think of since the middle 80's has had both an egr, evap, and pcv system. In fact the b series is kind of unique in that it does not have an egr.