Code 31 Nightmare
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5th Wheeling
Joined: Sep 2022
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Code 31 Nightmare
I have a 1991 E350 460 and it has been giving me a code 31. I have been browsing all the threads and posts I can related to this code and have tried almost everything I can at this point. I have bought new EVP sensors, new EGR, and two new ECMs. What I have found is that when I place a newer ECM 1995 and up the code goes away but when I place in an older ECM 1991-1993 the code comes back. I need to use the older computer because I have an older solenoid body in my transmission which does not work with the newer ecm. That being said I want this code to leave. I have checked all wires for continuity and voltage. Everything is within range. The only test I am unable to do is the code 35 which just results in the van not starting. I have also tried ohm readings between pin 27-40 and 46-60 on the ECM connector and I can never get a reading for either one. I don't know if I am doing the test wrong or what. Any help would be greatly appreciated!
Hotshot
Joined: Jul 2020
Posts: 10,529
Likes: 2,658
From: Near Salt Lake City
Pinpoint tests for code 31 need to be completed or you will be chasing your tail
There are no pinpoint tests in threads or posts, that I have seen, although I have posted some
You need AllData or a PCED
I'll post some of the tests for code 31
If a newer ride with a DPFE when code P0401 appears they have
Yours has none of that flow test diagnosis and just relies on the EVP sensor, which just senses the movement of the EGR pintle valve
Usually the casual part is the EVP itself. (the potentiometer on top of the EGR valve)
The diag goes all through it. The valve needs to operate so it goes through all the vacuum supply potential problems
God luck
I have a breakout box. We learned to back probe the sensor connectors so we could save time not messing with it
After the first 40 or so cars, Used to just jump on the evp and if that didn't fix it, then we would start the diagnosis
Ford made both white and black plastic colored evp's which are not interchangeable if I remember right
There are no pinpoint tests in threads or posts, that I have seen, although I have posted some
You need AllData or a PCED
I'll post some of the tests for code 31
If a newer ride with a DPFE when code P0401 appears they have
Yours has none of that flow test diagnosis and just relies on the EVP sensor, which just senses the movement of the EGR pintle valve
Usually the casual part is the EVP itself. (the potentiometer on top of the EGR valve)
The diag goes all through it. The valve needs to operate so it goes through all the vacuum supply potential problems
God luck
I have a breakout box. We learned to back probe the sensor connectors so we could save time not messing with it
After the first 40 or so cars, Used to just jump on the evp and if that didn't fix it, then we would start the diagnosis
Ford made both white and black plastic colored evp's which are not interchangeable if I remember right
Hotshot
Joined: Jul 2020
Posts: 10,529
Likes: 2,658
From: Near Salt Lake City
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Hotshot
Joined: Jul 2020
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Hotshot
Joined: Jul 2020
Posts: 10,529
Likes: 2,658
From: Near Salt Lake City
Sorry about the quality of those photos
You can get those exact pages free at your library on AllData
So back probe the signal return wire on that evp sensor connector and see just exactly what that evp is doing
probably nothing!
And ohm out processor pin 27 to that same wire on the evp sensor connector
Good luck
You can get those exact pages free at your library on AllData
So back probe the signal return wire on that evp sensor connector and see just exactly what that evp is doing
probably nothing!
And ohm out processor pin 27 to that same wire on the evp sensor connector
Good luck