90 f150 5.0 code 31 help
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4wd Low
Joined: Aug 2023
Posts: 11
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From: Eastern Long Island
90 f150 5.0 code 31 help
Okay so my 90 f150 5.0 auto I bought sat a long time and it runs good but it had a slight hesitation so I started with a tune up and a fresh iac and map and O2. Long story short my egr valve turned out to be leaking. (Wouldn’t hold vacuum) so i replaced my egr and evp. Immediately upon start up I received a CEL. Ran the codes with my scanner. KOEO and KOER i get a code 31. So I replaced my EVR and still have the code. I checked my ecm and all my capacitors were leaking so I decided to change my ecm with a fresh one. No change except it cranks longer to start now. So i wemt through my entire vacuum system and found no leaks. My truck is bone stock still has everything like when it was new. Im not sure if its related to my hesitation but my CEL is on and my egr is not functioning because of it. Update ** I vacuum tested the manifold vacuum port at the evr and have 15+ in of vacuum. I tested my egr and it opens and holds its vacuum with a mighty vac. If i can get my egr system working properly then i can look further into my hesitation. Also fuel psi is 37@idle and goes to 43ish when revved. Unplugged fpr and it goes to 45+. Any help is appreciated. Im at a loss.
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4wd Low
Joined: Aug 2023
Posts: 11
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From: Eastern Long Island
EVP testing starts at 3:45 in this video. https://youtu.be/Q9zwOKjhxM0?si=xrQdFRjRikv_cTHQ
yea i watched this and everything tested out. I replaced my evp and my evr too
Cargo Master
Joined: Aug 2021
Posts: 2,258
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From: Maryland
The voltage and resistance measurements at the EVP were ok?
When the engine is at operating temperature, if you rev the engine, can you see the pintle move that's at the center of the EGR valve?
When the engine is at operating temperature, if you rev the engine, can you see the pintle move that's at the center of the EGR valve?
Cargo Master
Joined: Aug 2021
Posts: 2,258
Likes: 742
From: Maryland
I would try the resistance test at the EVP, in the second post at this link, to see if resistance changes with varying levels of vacuum. https://www.fullsizebronco.com/threa...stance.297705/
Hotshot
Joined: Jul 2020
Posts: 10,456
Likes: 2,630
From: Near Salt Lake City
I would use the actual Ford pinpoint test steps for code 31
In the PCED
Did you replace the EVP with a Ford one?
The pinpoint tests start at DN 92 for code 31
There are only two pinpoint tests related to that code and the new EVP fixes most of them (all but the ones with wiring problems)
Here are the pinpoint tests
In the PCED
Did you replace the EVP with a Ford one?
The pinpoint tests start at DN 92 for code 31
There are only two pinpoint tests related to that code and the new EVP fixes most of them (all but the ones with wiring problems)
Here are the pinpoint tests
Hotshot
Joined: Jul 2020
Posts: 10,456
Likes: 2,630
From: Near Salt Lake City
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Hotshot
Joined: Jul 2020
Posts: 10,456
Likes: 2,630
From: Near Salt Lake City
The star tester sounds an alarm as you are wiggling wires if it finds a fault
The part where you are moving wires around in small sections all the way to the processor is impossible
Without a Start tester in continuous monitor mode
You can ohm out those wires to the processor and watch your DVOM
I think you might have a bad EVP sensor with a open circuit within
The part where you are moving wires around in small sections all the way to the processor is impossible
Without a Start tester in continuous monitor mode
You can ohm out those wires to the processor and watch your DVOM
I think you might have a bad EVP sensor with a open circuit within
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Thread Starter
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4wd Low
Joined: Aug 2023
Posts: 11
Likes: 0
From: Eastern Long Island
I would try the resistance test at the EVP, in the second post at this link, to see if resistance changes with varying levels of vacuum. https://www.fullsizebronco.com/threa...stance.297705/
i will try this tonight
Thread Starter
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4wd Low
Joined: Aug 2023
Posts: 11
Likes: 0
From: Eastern Long Island
I would use the actual Ford pinpoint test steps for code 31
In the PCED
Did you replace the EVP with a Ford one?
The pinpoint tests start at DN 92 for code 31
There are only two pinpoint tests related to that code and the new EVP fixes most of them (all but the ones with wiring problems)
Here are the pinpoint tests
In the PCED
Did you replace the EVP with a Ford one?
The pinpoint tests start at DN 92 for code 31
There are only two pinpoint tests related to that code and the new EVP fixes most of them (all but the ones with wiring problems)
Here are the pinpoint tests
so my egr system worked fine besides my leaking egr diaphragm. I replaced the egr valve and after that i had the code. So I replaced the evp and evr with no success. Basically what’s happening is im getting no vacuum from the evr to the egr. I have manifold vacuum at the evr but nothing going out to the egr when i bring the idle up. Also i tested the vacuum lines and all of them hold vacuum. No leaks. None of this started until I touched the leaking egr valve
4wd Low
Joined: Aug 2023
Posts: 10
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so my egr system worked fine besides my leaking egr diaphragm. I replaced the egr valve and after that i had the code. So I replaced the evp and evr with no success. Basically what’s happening is im getting no vacuum from the evr to the egr. I have manifold vacuum at the evr but nothing going out to the egr when i bring the idle up. Also i tested the vacuum lines and all of them hold vacuum. No leaks. None of this started until I touched the leaking egr valve
im having this exact problem! I’ve taken the same steps you have, any updates?
Hotshot
Joined: Jul 2020
Posts: 10,456
Likes: 2,630
From: Near Salt Lake City
The vacuum canister / reservoir is in the EGR circuit on some of them
Yours holds vacuum?
In some cases
We had to plug a big socket into the exhaust pipe with a pair of vise grips to create backpressure
Then the EGR will function in the shop
It is the processor that tells the EVR when to apply EGR vacuum
Your code 31 is the wiring and not the vacuum
I would be at the junkyard getting two EVPs and EVRs to plug in to test with
I would be ohming out the wires back and forth to the processor
Yours holds vacuum?
In some cases
We had to plug a big socket into the exhaust pipe with a pair of vise grips to create backpressure
Then the EGR will function in the shop
It is the processor that tells the EVR when to apply EGR vacuum
Your code 31 is the wiring and not the vacuum
I would be at the junkyard getting two EVPs and EVRs to plug in to test with
I would be ohming out the wires back and forth to the processor
4wd Low
Joined: Aug 2023
Posts: 10
Likes: 0
The vacuum canister / reservoir is in the EGR circuit on some of them
Yours holds vacuum?
In some cases
We had to plug a big socket into the exhaust pipe with a pair of vise grips to create backpressure
Then the EGR will function in the shop
It is the processor that tells the EVR when to apply EGR vacuum
Your code 31 is the wiring and not the vacuum
I would be at the junkyard getting two EVPs and EVRs to plug in to test with
I would be ohming out the wires back and forth to the processor
Yours holds vacuum?
In some cases
We had to plug a big socket into the exhaust pipe with a pair of vise grips to create backpressure
Then the EGR will function in the shop
It is the processor that tells the EVR when to apply EGR vacuum
Your code 31 is the wiring and not the vacuum
I would be at the junkyard getting two EVPs and EVRs to plug in to test with
I would be ohming out the wires back and forth to the processor
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