I have a 2001 Expedition. Recently the SES light came on w/PO401 code. I replaced the DPFE, reset the code. It came back in about 20 min. I removed the egr and inspected the ports, they looked pretty clean. I started the truck up with the egr removed and felt plenty of vac at the 2 ports that lead into the throttle body. I also noticed plenty of exhaust flow from the open pipe leading from the exhaust to the egr. Next, I reattached the egr and removed the DPFE and ran a weed eater string down both tubes, no obstruction. I restarted the engine and felt pressure from both ports. I reinstalled DPFE. Next, I placed vacuum on egr with engine running and detect a definite drop in rpms, not near shutting off, but definite rpm change. This has me focused on the evr. I removed it, disconnected the 2 prong connector and placed vacuum on it and it vents through the nozzle under the cap. Next, I reattched the connector and verified 12v to it with the switch on, engine off (and by the way, 35 ohms disconnected), and performed the same test, and got the same results. It vented through the top (no vacuum to green hose). It seems to me that in the energized state, there should be vacuum available to the green hose. I'm now officially stumped. What amI missing? Did I troubleshoot the evr correctly? Could the throttle body be partially obstructed and still pull hard vacuum?

 

Did you actually take off the throttlebody and check the two ports for blockage? I did this last weekend and they were ALMOST completely clogged. It isn't a tough job, you should try it. The port where the egr connects to teh throttle body turns into two smaller ports on the bottom side of the thottle body. Almost impossible to clean them without removing the throttlebody.

You didn't state your mileage (or you did and Im just retarded), but I'm guessing by the year, you have enough mileage on them to be clogged.

OR, the plastic hoses could be clogged. Check them first, but I'm going with the two ports on the throttle body.

 

If you purchased an aftermarket dpfe, I would suggest to test that also. There seems to be a problem with aftermarket dpfe's. I recently replaced one on a Taurus we own ( same style dpfe as the EXp) and it did not last very long. Do a search on dpfe's and follow the test procedure.

 

That's right, I forgot about this. For this part, Motorcraft replacement ONLY!

In fact, there is an extremely long thread (11 or 20 pages or something) on this subject here. Search it out, it is VERY helpful.

 

Thanks for the info on the throttle body. I will try that this weekend. I had just discounted it since I had strong vacuum at the 2 ports with the egr removed.

 

Thanks, i will search the records for that thread. i tested the dpfe and it seems to work properly (voltage rises when egr is opened by manual vacuum).