Engine Emission Control

WARNING: This page is about a different car, the 2005 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Do not remove any part of the engine emission control system. Operating the engine without the engine emission control system 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.
Exhaust gas recirculation (EGR) system (4.2L and 4.6L (2V) only).

Fig 1: Identifying Typical Vehicle Emission Control Information (VECI) Decal

Courtesy of FORD MOTOR CO.

The Vehicle Emission Control Information (VECI) decal shows:

Components of the emission control system.
The correct vacuum hose routing.
The color stripe of the vacuum hoses.

For additional information, refer to IDENTIFICATION CODES .

The PCV system uses intake manifold vacuum to ventilate the crankcase and return the fumes to the intake manifold for combustion.

The PCV valve:

Controls the amount of ventilating air and blow-by gases going to the intake manifold.

Fig 2: Identifying EGR System Components

Courtesy of FORD MOTOR CO.

The exhaust gas recirculation (EGR) system returns a portion of the exhaust gas to the intake manifold to reduce the combustion temperature. This results in lower nitrous oxide formation.

The powertrain control module (PCM) controls the EGR system module. The EGR system module controls the vacuum to the EGR valve. When the EGR valve opens, exhaust gas flows to the intake manifold. The EGR system module measures the flow through the EGR valve to the exhaust manifold tube and sends a signal to the powertrain control module.

The EGR system module-to-exhaust manifold tube:

Connects the exhaust manifold to the EGR system module.

The EGR system module:

Monitors the EGR system module flow rate through the EGR to exhaust manifold tube.
Sends an EGR system module flow rate signal to the powertrain control module.

The EGR system module uses input from the powertrain control module to change the EGR system module operation.