Go With the Flow
Some 1997 - 2004 Ford F-150 vehicles equipped with a 5.4L 2V engine may exhibit an intermittent rough idle. This may be due to a non-commanded EGR flow. EGR flow can be detected by comparing the stabilized DPFEGR KOER voltage at idle after manually opening and closing the EGR valve through eight cycles.
Record the DPFEGR voltage after each cycle. If the DPFEGR voltage increases by 0.03V or more from the stabilized idle voltage and is associated with a rough idle, the valve should be replaced.
1. Connect the NGS/WDS and monitor DPFEGR PID.
2. Record initial stabilized DPFEGR voltage.
3. Disconnect the EGR valve vacuum line and connect a hand-held vacuum pump.
4. Raise engine rpm to prevent stalling and fully open the EGR valve.
5. Fully close the EGR valve and return to idle.
6. Record stabilized DPFEGR voltage.
7. Repeat steps 4-6 eight times.
8. If voltage increases by 0.03V or more with a rough idle during any of the cycles, the EGR valve may be sticking. Lightly tap the EGR valve casting and observe if voltage returns to the initial DPFEGR value. If the voltage returns to the initial value and the rough idle concern is gone, replace the EGR valve. If there is no change in DPFEGR voltage, do not replace the EGR valve and perform normal diagnostics.
9. If the EGR valve is replaced, repeat steps 3-6 two times to verify the repair.