Ford 4.6 EGR Valve Problemsby Doug Bennett
The Ford 4.6-liter engine has been used in a variety of Ford, Lincoln and Mercury models since 1991. All versions are equipped with an exhaust gas recirculation (EGR) system to improve vehicle emissions.
EGR System Components
Your EGR system is comprised of several components. The EGR valve controls the flow of exhaust gas into your intake manifold. The EGR vacuum solenoid (EGR SV) controls the flow of engine vacuum. The differential pressure sensor (DPFE) monitors the EGR flow and reports to your EGR modulator, which controls your vacuum solenoid.
EGR Valve Problems
EGR valves contain a spring-actuated diaphragm. A common problem is a rupture or leak in the diaphragm. Check the function of your valve by revving the engine to around 2,000 rpm. If the valve stem does not move, the valve may be faulty. Clean the unit and test again. If faulty, the valve will need to be replaced.
Other EGR Problems
Ford EGR systems are known for faulty DPFEs. A bad sensor will illuminate the check engine light and trigger any of the following fault codes: P0171, P0174 and P0401. This unit is far more likely to fail than your EGR valve. Additionally, lack of vacuum pressure may indicate a clogged vacuum line or faulty solenoid.
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