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I just can't seem to fix the problem with this dang EGR. It's a 99 3.0 2wd auto with 86k miles and it started throwing the p0401 code. I replaced the vacuum solenoid with a motorcraft part, the 2 rubber lines from the egr tube, thoroughly cleaned the egr tube and inside the intake manifold. Still no luck. I replaced the DPFE with an Autozone part and it started throwing the p0402 excessive flow code. I also replaced the valve with an Autozone part. If I put the original motorcraft DPFE it will throw p0401. Either way, it takes quite a bit of drive time for the cel to come on. The codes are cleared with my scanner and I disconnect the battery each time I try something else. The egr tube has to be clean as it blows a lot of air thru all ports with my compressor. The egr valve works fine using a mighty vac. It opens with around 5 in of vacuum and seals well with no vacuum. I am starting to think Autozone sells junk and maybe I need a motorcraft DPFE. Any ideas?
I usually have a suggestion or two regarding EGR matters, but I'm as stumped as you are, sorry. It sounds like you've approached the problem exactly the way I would have.
You might get some more ideas by reading through the "DPFE/EGR System Monitor" section of this PDF article:
Hey Rockledge, thanks for the great info. I will thoroughly read thru it. I have a great book on EECIV but nothing on OBDII. I am going to back probe the DPFE and check some voltages before buying a new one. Maybe return the junk one to the Zone.
Super 6.8 can you tell me the wrench size used to remove the air tube on the EGR valve. I have a '99 that I suspect has a bad EGR. The air tube that connects to the bottom is very tight and appears to require a flare coupling (6 sided) wrench to remove it. I have a set but my largest is 19mm and this looks like a 21mm or so. I need to buy one but don't want to buy a whole set for something I'll rarely use.