EGR Tubes for (early; non-PFE/DPFE) 5.0L & 5.8L
IF THE IMAGE IS TOO SMALL, click it.
1 - Exhaust Gas Recirculation Valve 9D460
2 - EGR Valve to Exhaust Manifold Tube 9D477 (4.9L
F4TZ9D477C =
Dorman 598-105; 5.8L EVP FOTZ9D477A)
3 - EGR Tube Nuts (2); 34-47 N-m (25-35 Ft-Lb) (Part of 9D477)
4 - Adaptor; 34-47 N-m (25-35 Ft-Lb) N803575
5 - Intake Manifold Support 9J444
6 - Stud 5/16-18 x 1.85 Hex Shoulder; 20-27 N-m (15-20 Ft-Lb) 388377
7 - Nut 3/8-16; 16-24 N-m (12-18 Ft-Lb) 45358
8 - Manifold, Exhaust 9430
9 - Upper intake manifold 9K461
10 - EGR Valve Gasket 9D476
11 - Wiring Retainer 14A163
12 - EGR Valve Tube to Manifold Connector; 54-68 N-m (40-50 Ft-Lb) (Must be installed with flanged shoulder toward exhaust manifold.) 9F485
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Before madly ripping out all the emissions system systems on your vehicle, read
this article. The EGR section appears below.
Vacuum Operated EGR Systems-
The Exhaust Gas Recirculation (EGR) System is designed to reintroduce exhaust gas into the combustion cycle lowering combustion temperatures and reducing the formation of Nitrous Oxide.
Overview
The Exhaust Gas Recirculation (EGR) system controls the oxides of nitrogen (NOx) emissions. Small amounts of exhaust gases are recirculated back into the combustion chamber to mix with the air/fuel charge. The combustion chamber temperature is reduced, lowering NOx emissions.
The EGR system is enabled only during part throttle modes when the engine is warm and stabilized. These conditions exist after a length of time has elapsed since engine start-up, the Throttle Position (TP) sensor indicates part throttle, and the Engine Coolant Temperature (ECT) sensor indicates a warm engine. The EGR system is disabled by the Powertrain Control Module (PCM) whenever the TP sensor indicates closed throttle or wide open throttle. The disable function is necessary to avoid driveability concerns during idle and maximum power demands. While EGR gases are being introduced, the PCM also compensates for changes in the air/fuel ratio by modifying injector pulse width and ignition spark advance.
There are two basic types of EGR systems:
* The PFE/DPFE System (9J460 9D475)
* The EVP System 9F483 (9H473 9G428 )
The amount of exhaust gas reintroduced and the timing of the cycle varies by calibration and is controlled by factors such as engine speed, engine vacuum, exhaust system back pressure, coolant temperature and throttle angle. All EGR valves are vacuum actuated. The vacuum diagram is shown on the emission decal for each calibration.
Pressure Feedback EGR (PFE/DPFE) Systems -
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PFE is a subsonic closed loop EGR system that controls EGR flow rate by monitoring the pressure drop across a remotely located sharp-edged orifice. The system uses a pressure transducer (9J460) as the feedback device and controlled pressure is varied by valve modulation using vacuum output of the EGR Vacuum Regulator (EVR) solenoid (9J459). With a PFE system, the EGR valve only serves as a pressure regulator rather than a flow metering device. The Differential Pressure Feedback EGR (DPFE) system operates in the same manner except it directly monitors the pressure drop across the metering orifice. This allows for a more accurate assessment of EGR flow requirements.
System Components
PFE EGR Valve - 9D460 (9D475)
The PFE EGR valve is a conventional ported EGR valve. The service replacement for this valve is 9D475 which does not include the pickup tube/plug. The original pickup tube/plug should be used with the new service valve (9D475).
PFE and DPFE Sensors - 9J460
The Pressure Feedback EGR (PFE) and Differential Pressure Feedback EGR (
Motorcraft DPFE15) sensors convert a varying exhaust pressure signal into a proportional analog voltage which is digitized by the Powertrain Control Module (PCM). The PCM uses the signal received from the PFE or DPFE sensor to compute the optimum EGR flow.
The EVP EGR Valve is required in EEC systems where EGR flow is controlled by the Powertrain Control Module (PCM) through an EGR Valve Position (EVP) sensor attached to the valve.
The valve is operated by a vacuum signal from the EGR Vacuum Regulator (EVR) Solenoid (9J459) which actuates the valve diaphragm.
As supply vacuum overcomes the spring load, the diaphragm is actuated. This lifts the pintle off its seat allowing exhaust gas to recirculate (flow). The amount of flow is proportional to the pintle position. The EVP sensor mounted on the valve sends an electrical signal of its position to the PCM (12A650).
The EGR valve for this system is a vacuum operated EGR valve which maintains a sonic flow in the valve seat/pintle area.
The EVP sensor (9G428 ) and EGR valve (9H473) are serviced separately.
EGR Valve Position (EVP) Sensor - 9G428 Motorcraft CX1464
The EVP sensor provides the EEC system with a signal indicating position of the EGR valve.
EGR Vacuum Regulator (EVR) Solenoid - 9J459
The EGR Vacuum Regulator (EVR) solenoid is an electromagnetic device which controls vacuum output to the EGR valve. An electric current in the coil induces a magnetic field in the armature which pulls on a disk closing the vent to atmosphere. The Powertrain Control Module (PCM) outputs a duty cycle to the EVR which regulates the vacuum level to the EGR valve. As the duty cycle is increased, so is the vacuum signal to the EGR valve. The vacuum source is manifold vacuum.
On some applications, a current control thermistor device is also used to compensate for extreme temperature operation. The EVR solenoid and thermistor are serviced as an assembly.
Vacuum Reservoir - 9E453
The Vacuum Reservoir (coffee can) stores vacuum and provides "muscle" vacuum. It prevents rapid fluctuations or sudden drops in a vacuum signal such as those seen during an acceleration period.
Vacuum Reservoir Diagnosis -
When charged initially with 51-67 kPa (15-20 in-Hg) vacuum, vacuum loss shall not exceed 2 kPa (.5 in-Hg) in 60 seconds. If it does, replace the reservoir.
Vacuum Check Valve -12A197
A vacuum check valve blocks airflow in one direction and frees airflow in the other direction. The check side of this valve will hold the highest vacuum seen on the vacuum side. If not, replace it.
Vacuum Check Valve Diagnosis -
Apply 54 kPa (16 in-Hg) vacuum to "check" side of valve and trap. If vacuum remains above 50.6 kPa (15 in-Hg) for 10 seconds, the valve is acceptable.
See also:
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NOx/EGR Emissions:
To get the maximum power & efficiency from an engine, most designers set the fuel/air mixture slightly lean, and advance the ignition timing. But these adjustments also result in very high combustion temperatures, which allow the formation of oxides of Nitrogen (air's 2 main components). These compounds dissolve into rain to form acid which affects agriculture, lakes, & even stone buildings and paint. Another way to increase the engine's power is to reduce its moving mass by using Aluminum & its alloys for the pistons & connecting rods. But the high temperature can even oxidize the Aluminum & burn through the pistons, causing catastrophic engine failure. (Aluminum heads don't suffer as badly since they're water-cooled.) So to permit this increased performance, AND to reduce emissions, engineers found that introducing a metered quantity of inert exhaust gas back into the intake would significantly reduce the combustion temperature, WITHOUT a corresponding reduction in power or efficiency. As with other emissions systems, early implementations of EGR had problems that lead to a common misconception about its practicality. The engineers designing the alloy pistons weren't necessarily using the same design parameters as those developing the EGR systems, so both were overly conservative, and performance suffered. But modern engine management systems are more synchronized, and EGR is actually beneficial when properly maintained. Modern catalytic converters are also designed to reduce NOx emissions. Engines designed without EGR are either running rich (to keep the combustion temps down), or are using exceptionally-precise operating parameters to minimize NOx formation.
Failures in the EGR system commonly result from the same type of vacuum leaks & wiring damage that can affect the 2ndry air controls, but excessive soot in the exhaust can block the EGR journals in the intake, resulting in insufficient EGR flow. Also, the EGR valve's pintle can crack, allowing exhaust to pass even when the valve is commanded closed. There is a common misconception about water contamination inside the PFE/DPFE, but that water is safe & insignificant; the actual cause of that problem was a design flaw in the sensor itself, which has been corrected. On some older engines, the EGR's external tube is known to crack or rust allowing an exhaust leak, but modern tubes are stainless & much more reliable.
For more info about emissions systems, read
this article.
