System Overview
There are three emission control systems which are as follows
- Crankcase emission control system
- Exhaust emission control system Catalytic converter Air/fuel (A/F) control system Ignition control system
- Evaporative emission control system On-board refueling vapor recovery (ORVR) system
| Item | Main components | Function | ||
|---|---|---|---|---|
| Crankcase emission control system | Positive crankcase ventilation (PCV) valve | Draws blow-by gas into intake manifold from crankcase and burns it together with air-fuel mixture. Amount of blow-by gas to be drawn in is controlled by intake manifold pressure. | ||
| Exhaust emission control system | Catalytic converter | Pre | Catalytic converter | Oxidizes HC and CO contained in exhaust gases as well as reducing NOx. |
| Front | ||||
| Rear | ||||
| Air/fuel (A/F) control system | Engine control module (ECM) | Receives input signals from various sensors, compares signals with stored data, and emits a signal for optimal control of air-fuel mixture ratio. | ||
| Front oxygen (A/F) sensor | Detects density of oxygen contained exhaust gases. | |||
| Rear oxygen sensor | Detects density of oxygen contained in exhaust gases. | |||
| Throttle position sensor | Detects throttle opening. | |||
| Manifold absolute pressure sensor | Detects absolute pressure of intake manifold. | |||
| Mass airflow and intake air temperature sensor | Detects amount of intake air. | |||
| Detects intake air temperature at air cleaner case. | ||||
| Ignition control system | ECM | Receives various signals, compares signals with basic data stored in memory, and emits a signal for optimal control of ignition timing. | ||
| Crankshaft position sensor | Detects engine speed (revolution). | |||
| Camshaft position sensor | Detects reference signal for combustion cylinder discrimination. | |||
| Engine coolant temperature sensor | Detects coolant temperature. | |||
| Knock sensor | Detects engine knocking. | |||
| Evaporative emission control system | Canister | Absorbs evaporative gas which occurs in fuel tank when engine stops, and releases it to combustion chambers for a complete burn when engine is started. This prevents HC from being discharged into atmosphere. | ||
| Purge control solenoid valve | Receives a signal from ECM and controls purge of evaporative gas absorbed by canister. | |||
| Pressure control solenoid valve | Receives a signal from ECM and controls evaporative gas pressure in fuel tank. | |||
| ORVR system | Vent valve | Closes the port to the canister when the fuel tank is full of fuel. | ||
| Drain valve | Closes the evaporation line by receiving a signal from ECM to check the evaporation gas leak. | |||
MAIN COMPONENTS SPECIFICATIONS CHART
Scheme 17
Scheme 18
Scheme 19
- The positive crankcase ventilation (PCV) system prevents air pollution which will be caused by blow-by gas being emitted from the crankcase. The system consists of a sealed oil filler cap, rocker covers with fresh air inlet, connecting hoses, a PCV valve and an air intake duct.
- In a part-throttle condition, the blow-by gas in the crankcase flows into the intake manifold through the connecting hose of crankcase and PCV valve by the strong vacuum created in the intake manifold. Under this condition, fresh air is introduced into the crankcase through the connecting hose of the rocker cover.
- In a wide-open-throttle condition, a part of blow-by gas flows into the air intake duct through the connecting hose and is drawn into the throttle chamber, because under this is condition, the intake manifold vacuum is not strong enough to introduce through the PCV valve all blow-by gases that increase in the amount with engine speed.
- The PCV hose is provided with a leak detection function.