OBX Headers & P0401 code Heads-Up

[ww2willys]

Hey guys, just thought I would share something I encountered after installing the headers. I did an excellent transaction with MAS Tequila in Feb. 2016 and purchased the headers from him. I got them installed in the next couple of months. I know several people posted they had to heat up the EGR pipe to get it to fit. Mine was nowhere close to fitting and I had to add about an inch of pipe. There was no way just bending it would come close to being long enough. Even with no body mounted on the frame, it was more of a pain in the ass than it should have been.

Anyway, got them installed, sounded good - no leaks. Took me almost 18 months to finish my project and get it on the road. After the first 40 miles I got a check engine light with P0401 code- insufficient EGR flow. DPFE sensor was terribly corroded and looked original so I put a new Motorcraft DPFE on and kept driving. Unfortunately that didn't fix the problem so I went ahead and did the proper diagnostics. All the parts tested good individually so I'm scratching my head trying to figure it out. Thought maybe the Trick Flow cam i had tossed into the motor may be causing a low vacuum issue but that wasn't the problem. I was driving about 75 miles per day for 2 weeks and the light would come on every day between 40 and 60 miles.

Using a vacuum pump on each side of the DPFE sensor changed the voltage as is supposed to do so I knew the sensor was good. It seemed like the pressure wasn't changing in the EGR pipe. I looked at the original pipe and saw a crimp in between the 2 pressure tubes. I cut it open and saw the orifice in between the 2 tubes. I then looked at the OBX pipe and saw no crimp. Went ahead and cut open the OBX pipe up by the tubes and guess what - NO ORIFICE!! Cut the orifice section out of the original and pipe brazed it into the OBX. After another week of driving, no Check Engine Light! I hope this may help someone else if they also got an incorrectly built pipe.

 

[MuscleJunkie]

Awesome - excellent info. I've been looking at the same situation. Will give that a try. Thank You so much!

 

[98 MERC]

I kinda get what you did but kinda not.The pics don't really show what you found and what you did.I kinda see the end result but not that good.Are you saying that you cut that accordion looking piece from the stock egr tube and cut your obx tube and welded that accordion looking joint into the obx tube ?

 

[ww2willys]

Sorry, I didn't think about taking pictures while It was cut apart. As far as the accordion part, the OBX pipe does not not have the accordion section. I believe someone else said the new Motorcraft part doesn't have it either? The DPFE sensor is looking for different pressures at times between the 2 tubes that are connected by the rubber hoses. The way this is accomplished is by having an orifice in between the 2 tubes. The orifice is about a 1/8 inch thick metal ring inside the pipe. When the EGR valve opens, the pressure changes from one side of the tube to the other side due to the orifice not allowing the exhaust pressure to come straight thru.

I ended up cutting the upper portion of the original pipe just in front of the second tube, that way the orifice was already in place. I then brazed that original upper half to the lower half of the OBX pipe.Hope that makes more sense!

 

[98 MERC]

So to make this clear you did or didn't install the accordion piece from ford pipe into your obx pipe ? If i understand correctly you cut the top 2 tubes off the ford part and welded them onto the bottom half of the obx pipe correct ? Is this orifice inside of both pipes or just 1 ?

 

[VR4]

So to make this clear you did or didn't install the accordion piece from ford pipe into your obx pipe ? If i understand correctly you cut the top 2 tubes off the ford part and welded them onto the bottom half of the obx pipe correct ? Is this orifice inside of both pipes or just 1 ?

The orifice is in the large pipe between the 2 tubes going to the dpfe.

 

[shucker1]

What ever you do don't change the size of the orifice in the tube. The PCM has been programmed with that information. I knows the size and can therefore tell the amount of EGR flow by sensing the difference between the upstream and downstream pressures.

 

[MuscleJunkie]

Is it possible that OBX forgot to install the said orifice. What about the Torque Monsters? Can anyone comment about theirs?

 

[ww2willys]

98 MERC - I did not use the accordion piece. It has nothing to do with the orifice. As VR4 wrote, the orifice is in the large pipe between the 2 tubes. OBX definitely forget to install the orifice, the whole pipe was about an inch too short too! Other people posted the pipe had to be heated and bent in order to install. There was no way in hell bending it was going to make mine work.

 

[MuscleJunkie]

98 MERC - I did not use the accordion piece. It has nothing to do with the orifice. As VR4 wrote, the orifice is in the large pipe between the 2 tubes. OBX definitely forget to install the orifice, the whole pipe was about an inch too short too! Other people posted the pipe had to be heated and bent in order to install. There was no way in hell bending it was going to make mine work.

During my OBX install the EGR tube fit perfectly but I am getting the error code when not disabled in my SCT X4 tune. So I am curious if I should implement something from this post on my install to solve the error???

 

[shucker1]

Check the EGR tube first to see if the Orifice plate is in there.

Should be crimped between to 2 tubes that lead to the sensor.

You may have to get a salvage yard tube if you don't have your old one hanging around.

You may need to cut the O plate section out and have it installed in the new tube.

 

[MuscleJunkie]

Check the EGR tube first to see if the Orifice plate is in there.

Should be crimped between to 2 tubes that lead to the sensor.

You may have to get a salvage yard tube if you don't have your old one hanging around.

You may need to cut the O plate section out and have it installed in the new tube.

Thanks

 

[Turdle]

I had this egr issue when modifying our 98 Mounty. start at post 162 in this thread. I took some pictures lol

http://www.explorerforum.com/forums/index.php?threads/trying-to-get-it-right.195577/page-7

Hope this helps with understanding.

 

[Mitchs07explorer]

Hey guys, just thought I would share something I encountered after installing the headers. I did an excellent transaction with MAS Tequila in Feb. 2016 and purchased the headers from him. I got them installed in the next couple of months. I know several people posted they had to heat up the EGR pipe to get it to fit. Mine was nowhere close to fitting and I had to add about an inch of pipe. There was no way just bending it would come close to being long enough. Even with no body mounted on the frame, it was more of a pain in the ass than it should have been.

Anyway, got them installed, sounded good - no leaks. Took me almost 18 months to finish my project and get it on the road. After the first 40 miles I got a check engine light with P0401 code- insufficient EGR flow. DPFE sensor was terribly corroded and looked original so I put a new Motorcraft DPFE on and kept driving. Unfortunately that didn't fix the problem so I went ahead and did the proper diagnostics. All the parts tested good individually so I'm scratching my head trying to figure it out. Thought maybe the Trick Flow cam i had tossed into the motor may be causing a low vacuum issue but that wasn't the problem. I was driving about 75 miles per day for 2 weeks and the light would come on every day between 40 and 60 miles.

Using a vacuum pump on each side of the DPFE sensor changed the voltage as is supposed to do so I knew the sensor was good. It seemed like the pressure wasn't changing in the EGR pipe. I looked at the original pipe and saw a crimp in between the 2 pressure tubes. I cut it open and saw the orifice in between the 2 tubes. I then looked at the OBX pipe and saw no crimp. Went ahead and cut open the OBX pipe up by the tubes and guess what - NO ORIFICE!! Cut the orifice section out of the original and pipe brazed it into the OBX. After another week of driving, no Check Engine Light! I hope this may help someone else if they also got an incorrectly built pipe.

I’ve run into the same issue, the stock EGR pipe is too long to bend it to fit so I’m thinking about cutting it down and re-welding it fit, I have access to a laser welder that I think will do exactly what I need. I also purchased this flexible EGR tubing moddbox that I might try splicing onto the stock EGR pipe first. It’ll make connecting the pipe to the headers and the EGR much easier since it’ll have flexibily. So annoying that this is even a problem (thanks OBX).

 

[410Fortune]

thanks for posting this up!

TMH never came with an EGR tube like the OBX do
Sounds like that was a smart move, with TMH you re use or replace the factory EGR tube = no codes
The plumbing for this tube can be a pita but with the TMH I have always been able to bend up a factory style tube to fit, even with a 1" intake spacer.
I am glad for this thread because I was totally un aware of the pinch down/orifice/ restriction inside of the factory tube