1991 1999 ford explorer chilton User Manual

							Torque Specifications-3.0L Engine
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506 SPECIFICATION CHARTS 
						

							Torque Specifications-4.0L (VIN X) Engine
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SPECIFICATION CHARTS 507 
						

							Torque Specifications-5.0L Engine
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Chilton® Automotive Information Systems. © 2004 Thomson Delmar Learning. HOW TO USE THIS BOOK
SPECIFICATION CHARTS 509 
						

							
EMISSION CONTROLS
Positive Crankcase Ventilation (PCV) System
OPERATION
The PCV valve system vents crankcase gases into the engine air intake where they are burned with the fuel
and air mixture. The PCV valve system keeps pollutants from being released into the atmosphere, and also
helps to keep the engine oil clean, by ridding the crankcase of moisture and corrosive fumes. The PCV valve
system consists of the PCV valve, its mounting grommet, the nipple in the air intake and the connecting
hoses. On some engine applications, the PCV valve system is connected with the evaporative emission
system.
Cutaway view of the PCV valve and its operationClick to enlarge
The PCV valve controls the amount of vapors pulled into the intake manifold from the crankcase and acts as a
check valve by preventing air flow from entering the crankcase in the opposite direction. The PCV valve also
prevents combustion backfiring from entering the crankcase in order to prevent detonation of the accumulated
crankcase gases.
TESTING Remove the PCV valve from the valve cover or engine block mounting grommet. The PCV valve for
the 5.5L and 5.5L engine is mounted in the crankcase oil vent separator in a rubber grommet, or its
ventilation hose before the connection to the throttle body. The PCV valve for the 5.0L and 5.0L
engines is also mounted in a rubber grommet, which is installed towards the rear of the left-hand
valve cover. On the 5.0L engine, the PCV valve is located on top of the block by the firewall.
1. 
Shake the PCV valve. If the valve rattles when shaken, reinstall it and proceed to Step 5. If the valve
does not rattle, it is sticking and must be replaced.
2. 
Start the engine and bring it to normal operating temperature.
3. 
EMISSION CONTROLS 511 
						

							Check the PCV valve for vacuum at idle
Disconnect the closure (fresh air) hose from the air inlet tube (connects the air cleaner housing to the
throttle body).
5. 
Place a stiff piece of paper over the hose end and wait 1 minute. If vacuum holds the paper in place, the system is OK; reconnect the hose.
1. 
If the paper is not held in place, check for loose hose connections, vacuum leaks or blockage.
Correct as necessary.
2. 
6. 
REMOVAL & INSTALLATION Disconnect the vacuum hose from the PCV valve.
1. 
Remove the PCV valve from its mounting grommet.
2.  HOW TO USE THIS BOOK
512 TESTING 
						

							PCV system hose routing for the 2.3L and 2.5L engines
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REMOVAL & INSTALLATION 513 
						

							PCV system hose routing for the 3.0L engine-2.9L engine is similar
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514 REMOVAL & INSTALLATION 
						

							PCV system hose routing for the 4.0L engine
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To install, attach the PCV vacuum hose to the PCV valve, then insert the valve into its mounting
grommet.
5. 
Evaporative Emission Control System
OPERATION
Fuel vapors trapped in the sealed fuel tank are vented through the orifice vapor valve assembly in the top of
the tank. The vapors leave the valve assembly through a single vapor line and continue to the carbon canister
for storage until they are purged to the engine for burning.
Purging the carbon canister removes the fuel vapor stored in the carbon canister. The fuel vapor is purged via
a CANister Purge (CANP) solenoid or vacuum controlled purge valve. Purging occurs when the engine is at
normal operating temperature and off idle.
The evaporative emission control system consists of the following components: fuel vapor (charcoal) canister,
orificed vapor valve, fuel vapor CANister Purge (CANP) solenoid, pressure/vacuum relief fuel tank filler cap, HOW TO USE THIS BOOK
Evaporative Emission Control System 515 
						

							
as well as, the fuel tank and fuel tank filler pipe, vapor tube and fuel vapor hoses.
Fuel Vapor (Charcoal) Canister
The fuel vapor canister is referred to as the evaporative emissions canister on 1441-44 models.
The fuel vapors from the fuel tank are stored in the fuel vapor canister until the vehicle is operated, at which
time, the vapors will purge from the canister into the engine for consumption. The fuel vapor canister contains
activated carbon, which absorbs the fuel vapor. The canister is located in the engine compartment or along the
frame rail.
Orificed Vapor Valve
This component is also known as the evaporative emission valve on 1441-44 models.
Fuel vapor in the fuel tank is vented to the carbon canister through the vapor valve assembly. The valve is
mounted in a rubber grommet at a central location in the upper surface of the fuel tank. A vapor space
between the fuel level and the tank upper surface is combined with a small orifice and float shut-off valve in
the vapor valve assembly to prevent liquid fuel from passing to the carbon canister. The vapor space also
allows for thermal expansion of the fuel.
CANP Solenoid
The CANP solenoid is inline with the carbon canister and controls the flow of fuel vapors out of the canister.
It is normally closed. When the engine is shut OFF, the vapors from the fuel tank flow into the canister. After
the engine is started, the solenoid is engaged and opens, purging the vapors into the engine. With the solenoid
open, vapors from the fuel tank are routed directly into the engine.
Pressure/Vacuum Relief Fuel Tank Filler Cap
The fuel cap contains an integral pressure and vacuum relief valve. The vacuum valve acts to allow air into
the fuel tank to replace the fuel as it is used, while preventing vapors from escaping the tank through the
atmosphere. The vacuum relief valve opens after a vacuum of -0.21 psi (1.2 kPa). The pressure valve acts as a
backup pressure relief valve in the event the normal venting system is overcome by excessive generation of
internal pressure or restriction of the normal venting system. The pressure relief is 2 psi (14 kPa). Fill cap
damage or contamination that stops the pressure vacuum valve from working may result in deformation of the
fuel tank.
COMPONENT TESTING HOW TO USE THIS BOOK
516 OPERATION