Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD2012EXPEDITION 2WD V8-5.4LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTEMISSION CONTROL SYSTEMSDESCRIPTION AND OPERATION
2012 Ford Expedition 2WD V8-5.4L
Emission Control Systems: Description and Operation
2012 Ford Expedition 2WD V8-5.4LSECTION Description and Operation
Engine Emission Control
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 law.
NOTE: The vehicle emission vacuum routing diagrams are contained in the Description and Operation of the Evaporative Emissions system.
The gasoline engine emission control system consists of the PCV system.
PCV System
The PCV system:
- uses intake manifold vacuum to ventilate blow-by gases from the crankcase.
- returns the gases to the intake manifold for combustion.
The PCV valve:
- varies the amount of blow-by gases returned to the intake manifold based on available engine vacuum.
- is integral to the LH valve cover.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.