PO401 Insufficient EGR flow

[delcogod]

I get this code on a daily basis. I have a 1997 2wd ext cab 4L. I've changed the EGR valve and pipe to exhaust, the two small modules above the EGR valve, the three O2 sensors, mass air flow sensor and the cat converter. (OEM style) Yet the code remains. When I read the code, I can then erase it, but get pending warns for most of the parts I've listed above. Its not a cheap reader, I bought it from my Snap On dealer. I've also either changed, or blown out the vaccum lines. Idon't know where to go, any help would be appreciated.

 

[Yellowsplash]

Usually this code is thrown when the DPFE sensor goes bad...its the sensor thats above the egr valve with 2 vacuum hoses goin to it.

 

[fordwheelinman]

Fine a piece of line that will tightyly go over the vacuum port on the egr valve. Start the truck and let it idle for 30 seconds or so. Suck on the line attached to the vavles port with either a hand vacuum pump, or with your mouth. NOT AN ELECTRIC PUMP!!! The engine should stumble, run really poorly, and maybe stall out. If it does not stumble badly, or does not stumble at all, you most likely have stopped up egr ports in the intake manifold. It has been awhile since i have looked at that specific gen or 4 litre, but if you remove the valve, and can clean out the deposits from inside the ports in the intake (or throttle body as the case may be) you should be set. Before starting to truck try sucking on the line to see if in fact your new valve is working. The O2 sensors, convertor, and maf have absolutely nothing to do with the egr system. If you operate the egr valve, and the engine stumbles badly, and you have the code still, most often the problem is with the DPFE sensor. If it only slightly stumbles, then you have partially blocked ports, or a partially functioning valve.

 

[fordwheelinman]

any staus updates?

 

[delcogod]

It has been resolved. Unfortunatley, I was following the "typical" 4L illustration in the Haynes manuel when I installed the DPFE sensor. It has the vaccum lines reversed. It never made sense to me why they had small to large and large to small shown, especially wit a DIFFERENTIAL transducer. I reversed the lines as the block diagram shows and everything has been fine. So, if you're using a Haynes book, be careful. This is the first mistake I've ever seen in their books. A big thanks for all of your help.

 

[FL_forlife33]

I've had the same problem with my 3.0L V6, P0401 "egr flow insufficient", replaced the egr valve, and same code comes up...

i use haynes as well, what part should I look out for?

 

[Destroyer000]

dpfe sensor..