Engine Emission Control

ENGINE EMISSION CONTROL

CAUTION: Do not run the engine with any part of the engine emission control system removed. Operating the engine without the engine emission control system intact will reduce fuel economy and engine ventilation. This will weaken engine performance and shorten engine life.

The engine emission control system consists of:
- the positive crankcase ventilation (PCV) system
- the exhaust gas circulation (EGR) system

Positive Crankcase Ventilation (PCV) System
The PCV system:
- uses intake manifold vacuum to remove blow-by fumes from the crankcase
- returns the fumes to the intake manifold for combustion

The positive crankcase ventilation (PCV) valve:
- varies the amount of blow-by gases returned to the intake manifold based on available engine vacuum
- prevents the entry of combustion backfiring into the crankcase

The PCV system consists of:
- crankcase ventilation tube
- positive crankcase ventilation valve
- crankcase vent oil separator
- crankcase pressure relief hose and valve assembly

Exhaust Gas Recirculation (EGR) System
The EGR system:
- returns a small amount of exhaust gas into the engine for composition
- reduces the overall combustion temperature and provides a significant reduction of oxide of nitrogen (NOx)

The EGR valve:
- is electronically controlled by the powertrain control module (PCM)
- controls the vacuum to the EGR valve

The EGR valve:
- is connected to the exhaust manifold by the EGR valve to exhaust manifold tube
- controls recirculated exhaust gas flow to the intake manifold
- monitors the flow of recirculated exhaust gases through the EGR valve to exhaust manifold tube
- returns a signal to the powertrain control module

The amount of recirculated exhaust gas depends upon:
- engine speed
- intake manifold vacuum
- exhaust back pressure
- engine coolant temperature
- throttle position

The vehicle emission control information decal:
- is located on the hood
- lists the exhaust emission control system information