Engine Emission Control: Notes
WARNING: This page is about a different variant/trim than selected.
NOTE:
Do not permanently remove or render inoperative any part of the vehicle emission control system including related hardware. Failure to comply may violate applicable state and federal laws.
The engine emission control system consists of the:
- EGR system.
- PCV system.
EGR System - The EGR system returns a small amount of exhaust gas into the intake manifold. This reduces the overall combustion temperature. Cooler combustion temperatures provide a significant reduction of the oxides of nitrogen (NOx) in the exhaust emissions.
The EGR valve:
- is electronically controlled by the PCM.
- 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 PCM.
The amount of recirculated exhaust gas depends upon:
- engine RPM.
- intake manifold vacuum.
- exhaust back pressure.
- engine coolant temperature.
- throttle position (TP).
The exhaust manifold to EGR valve tube:
- is shorter on an all wheel drive (AWD) vehicle than on a front wheel drive (FWD) vehicle.
PCV System - The PCV system:
- uses intake manifold vacuum to ventilate blow-by vapors from the crankcase.
- returns the vapors to the intake manifold for combustion.
The PCV system consists of the:
- crankcase ventilation tube.
- PCV valve.
The PCV heater element:
- heats the ventilating air and blow-by vapors going to the intake manifold.