Your Vehicle: 2001 Ford Escort ZX2 L4-2.0L DOHC VIN 3
Vehicle » Powertrain Management » Emission Control Systems » Description and Operation » Description and Operation  
  Description and Operation  

CAUTION: Do not remove any part of the engine emission control system. 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:

Positive Crankcase Ventilation (PCV) System
The PCV system:

  • uses intake manifold vacuum to ventilate 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: