Ford F150 Pickup. Instruction — part 1644

Fig. 75: Identifying Remote Mounted DPFE EGR Sensors
Courtesy of FORD MOTOR CO.

Differential Pressure Feedback EGR Sensor (Tube Mounted)

Tube mounted DPFE EGR sensor is identical in operation as remote mounted larger metal or plastic DPFE
sensors and uses a one volt offset. HI and REF hose connections are marked on underside of sensor. See Fig.
76 .

Fig. 76: Identifying Tube Mounted DPFE EGR Sensor

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

Courtesy of FORD MOTOR CO.

EGR Vacuum Regulator Solenoid

Vacuum regulator solenoid is an electromagnetic device used to regulate vacuum supply to the EGR valve.
EGR vacuum regulator solenoid contains a coil which magnetically controls the position of a disk to regulate
the vacuum. As the duty cycle to coil increases, vacuum signal passed through the EGR vacuum regulator
solenoid to the EGR valve also increases. Vacuum not directed to the EGR is vented to atmosphere. At zero
percent duty cycle (no electrical signal applied), EGR vacuum regulator solenoid allows some vacuum to pass,
but not enough to open EGR valve.

EGR Valve

EGR valve in the DPFE EGR system is a conventional, vacuum actuated EGR valve. The valve increases or
decreases flow of exhaust gas recirculation. As vacuum applied to EGR valve diaphragm overcomes spring
force, valve begins to open. As vacuum signal weakens, at 1.6 in. Hg (5.4 kPa) or less, spring force closes
valve. EGR valve is fully open at about 4.5 in. Hg (15 kPa). Since EGR flow requirement varies greatly,
providing service specifications on flow rate is impractical. The OBD-II system monitors EGR valve function
and triggers a DTC if test criteria is not met. EGR valve flow rate is not measured directly as part of field
diagnostic procedures.

Orifice Tube Assembly

Orifice tube assembly is the section of tubing connecting exhaust system to intake manifold. Orifice tube
provides a flow path for exhaust gas to intake manifold. The orifice tube contains a metering orifice and 2
pressure pick-up tubes. See Fig. 77 . The metering orifice creates a measurable pressure drop across it as EGR
valve opens and closes. The pressure differential across the orifice is picked up by DPFE EGR sensor which
provides feedback to PCM.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

Fig. 77: Identifying EGR Orifice Tube Assembly
Courtesy of FORD MOTOR CO.

ELECTRIC EGR MOTOR SYSTEM

Electric EGR (EEGR) motor/valve system uses exhaust gas recirculation to control Oxides of Nitrogen (NOx)
emissions just like vacuum operated systems. The difference is the way in which exhaust gas is controlled.
Advantages to this type of system are:

z

EEGR valve is activated by an electric stepper motor not a vacuum motor. It is located at rear of engine
block.

z

No vacuum diaphragm is used.

z

No DPFE sensor is used.

z

No Orifice Tube Assembly is used.

z

No EGR vacuum regulator solenoid is used.

z

A new MAP sensor is used. A TMAP is used, but temperature function is not used at this time. TMAP is
located on top of valve cover.

z

Engine coolant is routed through the assembly, extending durability of electric motor.

EEGR system consists of an electric EGR motor/valve integrated assembly, a PCM, TMAP sensor and
connecting wiring. The following list of components and their specific operation corresponds to numbers in

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

illustration. See

Fig. 78

.

1. EEGR system receives signals from Engine Coolant Temperature (ECT) or Cylinder Head Temperature

(CHT) sensor, Throttle Position (TP) sensor, Mass Airflow (MAF) sensor, Crankshaft Position (CKP)
sensor and Thermal Manifold Absolute Pressure (TMAP) sensor to provide information on engine
operating conditions to PCM. Engine must be warm, stable and running at a moderate load and engine
speed (RPM) before EEGR system is activated. PCM will deactivate EGR during idle, extended Wide
Open Throttle (WOT), or whenever a failure is detected in an EEGR component or EGR required input.

2. PCM calculates desired amount of EGR for a given set of engine operating conditions.

3. PCM in turn will output signals to EEGR motor to move (advance or retract) a certain number of discrete

steps. Electric stepper motor will directly actuate EGR valve, independent of engine vacuum. EGR valve
is commanded from 0-52 discrete increments or "steps" to move EGR valve from a fully closed to full or
partially open position. The position of EGR valve determines EGR flow.

4. TMAP sensor is used to measure variations in manifold pressure as exhaust gas recirculation is

introduced into intake manifold. Variations in EGR being used will correlate to TMAP signal. Increasing
EGR will increase manifold pressure values.

EEGR valve is a water cooled motor/valve assembly. See Fig. 79 and Fig. 80 . The motor is commanded to
move in 52 discrete steps as it acts directly on EGR valve. Position of valve determines rate of EGR flow. The
built in spring works to close valve against motor opening force.

Fig. 78: Identifying Electric EGR Motor System Components & Circuits (1 Of 2)
Courtesy of FORD MOTOR CO.

NOTE:

A TMAP is used, but temperature function is not used at this time.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline