Why the CEL?
Thread Starter
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Cargo Master
Joined: Oct 2008
Posts: 2,308
Likes: 1
From: Elyria, OH
Why the CEL?
1996 F250, 5.8 E4OD
I get the truck running great, the CEL comes on and the whole time it ran like crap i never got a CEL... Here are the codes:
KOEO: 111
CM: 332-EGR valve opening not detected.
334-DPFE or EVP circuit above the closed limit of 0.67 volts.
KOER: 311-Thermactor air system inoperative (right side)
332-EGR valve opening not detected.
Now i dont see any of those codes that should be throwing a CEL. I have the EGR hooked up, but no vac line goes to it due to it effin up my idle and making the truck stall. I have changed the EVP 2x so idk why i get that one. The thermactor system has been long gone on 3 of my trucks and never got a CEL.
Help me out here. truck runs the best it ever has with no issues, but i dont understand why the CEL is on!! I will check them again when i get my code reader in a couple of hours, i checked them this time with the jumper between the SNG_RTN and the self test.
I get the truck running great, the CEL comes on and the whole time it ran like crap i never got a CEL... Here are the codes:
KOEO: 111
CM: 332-EGR valve opening not detected.
334-DPFE or EVP circuit above the closed limit of 0.67 volts.
KOER: 311-Thermactor air system inoperative (right side)
332-EGR valve opening not detected.
Now i dont see any of those codes that should be throwing a CEL. I have the EGR hooked up, but no vac line goes to it due to it effin up my idle and making the truck stall. I have changed the EVP 2x so idk why i get that one. The thermactor system has been long gone on 3 of my trucks and never got a CEL.
Help me out here. truck runs the best it ever has with no issues, but i dont understand why the CEL is on!! I will check them again when i get my code reader in a couple of hours, i checked them this time with the jumper between the SNG_RTN and the self test.
Cargo Master
Joined: Jul 2009
Posts: 2,541
Likes: 54
From: Des Moines
Any one of those codes could trigger a CEL, but if I had to guess it's likely the 334- electronic signal codes tend to set it off.
Try resetting your computer. You can do this by unhooking the battery for 15 minutes. Your code reader should also be equipped with a procedure to reset it. Otherwise the codes will remain until the engine has been started 30 times without any new codes being triggered.
Once it's been reset, take it on a good 20-30 minute drive. Try to include city and highway driving if you can. Even if you don't get a CEL, check the codes anyway as there doesn't have to be a CEL for codes to be stored. This will tell you if all those codes are still accurate, or if only one or two of them still need attention.
Try resetting your computer. You can do this by unhooking the battery for 15 minutes. Your code reader should also be equipped with a procedure to reset it. Otherwise the codes will remain until the engine has been started 30 times without any new codes being triggered.
Once it's been reset, take it on a good 20-30 minute drive. Try to include city and highway driving if you can. Even if you don't get a CEL, check the codes anyway as there doesn't have to be a CEL for codes to be stored. This will tell you if all those codes are still accurate, or if only one or two of them still need attention.
Thread Starter
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Cargo Master
Joined: Oct 2008
Posts: 2,308
Likes: 1
From: Elyria, OH
Any one of those codes could trigger a CEL, but if I had to guess it's likely the 334- electronic signal codes tend to set it off.
Try resetting your computer. You can do this by unhooking the battery for 15 minutes. Your code reader should also be equipped with a procedure to reset it. Otherwise the codes will remain until the engine has been started 30 times without any new codes being triggered.
Once it's been reset, take it on a good 20-30 minute drive. Try to include city and highway driving if you can. Even if you don't get a CEL, check the codes anyway as there doesn't have to be a CEL for codes to be stored. This will tell you if all those codes are still accurate, or if only one or two of them still need attention.
Try resetting your computer. You can do this by unhooking the battery for 15 minutes. Your code reader should also be equipped with a procedure to reset it. Otherwise the codes will remain until the engine has been started 30 times without any new codes being triggered.
Once it's been reset, take it on a good 20-30 minute drive. Try to include city and highway driving if you can. Even if you don't get a CEL, check the codes anyway as there doesn't have to be a CEL for codes to be stored. This will tell you if all those codes are still accurate, or if only one or two of them still need attention.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
Invest in a cheap DVM and measure what the EVP signal is before spending money on another EVP. I suspect it is Code 334 tripping the CEL. An EGR valve that cannot completely close due to build up or some other issue can cause the closed signal value to be above 0.67 VDC.
Going on the theory the EGR valve is already off the seat a little, when you hook up the vacuum line via the EVR there may be a slight vacuum applied to the EGR itself. Now the EGR comes off the seat a bit more which creates a vacuum leak which in turn causes drive-ability issues. I see a pattern here.
Going on the theory the EGR valve is already off the seat a little, when you hook up the vacuum line via the EVR there may be a slight vacuum applied to the EGR itself. Now the EGR comes off the seat a bit more which creates a vacuum leak which in turn causes drive-ability issues. I see a pattern here.
Thread Starter
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Cargo Master
Joined: Oct 2008
Posts: 2,308
Likes: 1
From: Elyria, OH
Invest in a cheap DVM and measure what the EVP signal is before spending money on another EVP. I suspect it is Code 334 tripping the CEL. An EGR valve that cannot completely close due to build up or some other issue can cause the closed signal value to be above 0.67 VDC.
Going on the theory the EGR valve is already off the seat a little, when you hook up the vacuum line via the EVR there may be a slight vacuum applied to the EGR itself. Now the EGR comes off the seat a bit more which creates a vacuum leak which in turn causes drive-ability issues. I see a pattern here.
Going on the theory the EGR valve is already off the seat a little, when you hook up the vacuum line via the EVR there may be a slight vacuum applied to the EGR itself. Now the EGR comes off the seat a bit more which creates a vacuum leak which in turn causes drive-ability issues. I see a pattern here.
Elder User
Joined: Jan 2011
Posts: 884
Likes: 0
From: Rockport, IN
I dont feel any vac from the EVR to the EGR at idle, but when i put the vac line onto the EGR the motor stumbles and stalls (sometimes). With it off the truck runs great. Havent driven it this way, always did it at idle so i just unhooked it. Do you think i need to just clean the valve and see if that helps? Ill see if i can find my DVM. I have one... somewhere
Cleaning the valve would help if there are carbon issues keeping it from closing all the way. If you have a hand operated vacuum pump, you can use it to check that the valve is working properly without any leaks.
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Elder User
Joined: Feb 2008
Posts: 797
Likes: 1
From: ohio
You could make a pop can block off gasket for the egr valve and hook up the line. Then the valve can move without actually doing anything to cause problems.
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Thread Starter
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Cargo Master
Joined: Oct 2008
Posts: 2,308
Likes: 1
From: Elyria, OH
As for cleaning the valve, how would i go about that? take it off and let it soak in something and then use a hand vac to operate it and let it soak some more? Or just use carb cleaner and spray it down?
Thread Starter
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Cargo Master
Joined: Oct 2008
Posts: 2,308
Likes: 1
From: Elyria, OH
I understand that. But at idle i put the vac line on from the EVR and the engine stumbles and stalls. So either the EGR isnt closing properly and opens slightly more with the line applied or my EVR is bad and letting vac through the line at idle. but i do not feel and vac with my hand?
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
Is your hand calibrated to gauge 0.5, 1.0 or 2.0 inches of vacuum? All it takes is a very small amount of vacuum to start moving the EGR diaphragm. If you used a vacuum gauge you could confirm or debunk this theory in a few minutes.
Thread Starter
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Cargo Master
Joined: Oct 2008
Posts: 2,308
Likes: 1
From: Elyria, OH
No sir its not! I thought id be able to feel it, but i guess i am wrong. Are the hand vacs expensive?
Elder User
Joined: Jan 2011
Posts: 884
Likes: 0
From: Rockport, IN
I understand that. But at idle i put the vac line on from the EVR and the engine stumbles and stalls. So either the EGR isnt closing properly and opens slightly more with the line applied or my EVR is bad and letting vac through the line at idle. but i do not feel and vac with my hand?