1991 1999 ford explorer chilton User Manual

The sensor utilizes a hot wire sensing element to measure the amount of air entering the engine. The sensor
does this by sending a signal, generated by the sensor when the incoming air cools the hot wire down, to the
PCM. The signal is used by the PCM to calculate the injector pulse width, which controls the air/fuel ratio in
the engine. The sensor and plastic housing are integral and must be replaced if found to be defective.
The Mass Air Flow (MAF) sensor is mounted to the air cleaner housing
The...

MAF sensor wire harness connections
Click to enlarge
REMOVAL & INSTALLATION CAUTION
The mass air flow sensor hot wire sensing element and housing are calibrated as a unit and must be serviced
as a complete assembly. Do not damage the sensing element or possible failure of the sensor may occur.
Disconnect the negative battery cable.
1.  HOW TO USE THIS BOOK
548 TESTING 

To remove the MAF sensor, first disconnect the wire harness plug ...
... then remove the air cleaner-to-throttle body air tube
Disengage the wiring harness connector from the MAF sensor, and if necessary, the IAT sensor.
2. 
Loosen the engine air cleaner outlet tube clamps, then remove the tube from the engine.
3. 
Remove the MAF sensor from the air cleaner assembly by disengaging the retaining clips.
4. 
Remove the four MAF sensor attaching screws ...HOW TO USE THIS BOOK
REMOVAL & INSTALLATION 549 

... then remove the sensor from the air cleaner housing
To install:
Install the MAF sensor to the air cleaner assembly and ensure that the retaining clips are fully
engaged.
5. 
Install the air cleaner outlet tube, then tighten the outlet tube clamps until snug.
6. 
Attach the engine wiring harness connectors to the IAT and MAF sensors.
7. 
Connect the negative battery cable.
8. 
Throttle Position (TP) Sensor
OPERATION
The Throttle Position (TP) sensor is a potentiometer that provides a signal to the PCM...

Typical Throttle Position (TP) sensor mounting on the throttle body
TESTING Disconnect the negative battery cable.
1. 
Disengage the wiring harness connector from the TP sensor.
2. 
Using a Digital Volt-Ohmmeter (DVOM) set on ohmmeter function, probe the terminals, which
correspond to the Brown/White and the Gray/White connector wires, on the TP sensor. Do not
measure the wiring harness connector terminals, rather the terminals on the sensor itself.
3. 
Slowly rotate the throttle shaft and monitor the...

TP sensor wire harness connections
REMOVAL & INSTALLATION Disconnect the negative battery cable.
1. 
To remove the TP sensor, first disconnect the wire harness plug from the sensor
If the mounting holes of the sensor are slotted, mark its position. Note: factory sensors are not slotted
Disengage the wiring harness connector from the TP sensor.
2. 
Remove the two TP sensor mounting screws, then pull the TP sensor out of the throttle body housing.
3.  HOW TO USE THIS BOOK
552 TESTING 

Remove the two attaching screws ...
... then remove the sensor from the throttle body by lifting straight up to disengage the throttle blade (arrow)
To install:
Position the TP sensor against the throttle body housing, ensuring that the mounting screw holes are
aligned. When positioning the TP sensor against the throttle body, slide the sensor straight onto the
housing.
4. 
Install and tighten the sensor mounting screws until snug.
5. 
Attach the wiring harness connector to the sensor, then connect the...

1991-93 2.3L and 1991-95 4.0L (VIN X) engines did not use CMP sensors.
1994 2.3L California only and 1995-99 2.3L and 2.5L engines utilize CMP sensors. The 1994 CMP is located
on the oil pump drive assembly, on the left-hand lower side of the engine block. 1995-99 models CMP
sensor is located and triggered by the auxiliary shaft drive sprocket.
On the 1991-94 2.9L and 3.0L engine, the distributor stator is the Camshaft Position (CMP) sensor, and it is a
Hall effect magnetic switch. On the 1995-99 3.0L...

Oil pump drive mounted CMP sensor used on 3.0L, 4.0L and 5.0L engines and 1994 California
2.3L engines
On the 4.0L SOHC engine (VIN E), the Camshaft Position (CMP) sensor is a variable reluctance sensor,
which is triggered by the high-point mark on the left-hand camshaft. It is mounted to the valve cover.
The 4.0L and 5.0L engines use a separate CMP sensor mounted to the oil pump drive. The drive assembly is
located toward the rear of the engine on the 4.0L, and towards the front on the 5.0L engine....

CMP sensor wire harness connections for the 3-wire sensor
Click to enlarge
Two Wire Sensors With the ignition OFF, install a break-out box between the CMP sensor and PCM.
1. 
Using a Digital Volt-Ohmmeter (DVOM) set to the voltage function (scale set to monitor less than 5
volts), measure the voltage between break-out box terminals 24and 46with the engine running at
varying RPM. If the voltage reading varies more than 0.1 volt AC, the sensor is okay.
2. 
CMP sensor wire harness connections for the 2-wire...