We have an '02 Escape w/ v-6 auto, 4X4 and a little over 100,000 miles on the clock. Just when we were preparing for the state emissions inspection, the CEL came on with a P0401 insufficient EGR flow. We changed the EGR sensor, solenoid, and the EGR valve. Also replaced, were all vacuum lines anywhere near the EGR system, and both lines to the EGR sensor. We checked for any blockages, even going as far as removing the intake manifold. When the CEL came on we experienced a rough idle, which smoothed with the vacuum line removed from the EGR valve. As our immediate concern was getting through the emissions, we cleared the code and did a drive cycle. As soon as the EGR readiness monitor came on, the CEL came back on, this time with a P0402 code, too much exhaust flow. We switched sensors, solenoids, and EGR valves in every combination with no change. We still have a rough idle and a CEL with a P0402 code. Any ideas?
Thanks, Butch

 

Many time I have found the EGR tube to be the problem. It has an orifice between the DPFE tubes. It enlarges and set the CEL. I have never had one blocked.

Rod

 

I replaced one on the '97 Ranger "only" because the fitting was rusted solid to the EGR valve. I had to laugh as it's an orifice which you'd think is a small hole but actually looked like a washer, the hole was that big.

 

From what I understand, there should be no EGR flow at idle. If you remove the vacuum line to the EGR valve, and the idle roughness disappears, then likely you have vacuum to the valve. That could imply that whatever controls the vacuum is not working properly, as in leaks. I think the solenoid is the controlling device.
I would check for leaks. As far as the 'orifice', the diameter controls the flow at a given pressure, and would change depending on the displacement of the engine. If I were doing it, the orifice would be a 'trapped' cylinder with a ridge, and a shaped diameter that is retained by the EGR valve and a smidge of friction for assembly ease. That way you could use standard diameter tubing and fittings and only have the orifice itself as 'factory designed' stuff. What. Ever.
Check the solenoid for leakage.
tom

 

One can find posts in forums talking about modified engines needing different orifice tube washers which comes in kits but nothing about the actual orifice size.

Wherever the DPFE ports are, the orifice is between them and the tube is crimped or staked to hold it in place.

 

Solved! We had a cracked intake plenum, caused by a continuous flow of exhaust through faulty solenoid (?) The first replacement solenoid from NXXX was bad as well- they did exchange it though. So emissions good for another year. Thanks guys.

 

I have the same problem as u thinking its a vacum leak can u share please how u found out its a plenum crack ? Since I really cant find my leak.
What is the solenoid u r talking about ?
I just had the whole emission parts replace along with new spark plugs and all new plenum gaskets installed. Due to a misfire on 6 also replace the 6 coil.
Thank u in advance

 

A mechanic friend suggested the possibility of a crack, so after a trip to the U-pull it yard, the engine was running smooth. He also checked the other components and found the new solenoid (between the EGR valve and sensor) faulty. After replacement and drive cycle, we were good to go. I believe the crack was near the EGR valve mounting point.