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Discussion Starter #1 (Edited)
KOEO/KOER 31 HELP!!!

Bought this BKO in Oct of 2007 and have had this code ever since. I have spent about 4 months searching on here, other ford message boards and the internet on trying to remove this code and now I am at my wits end.:banghead

KOEO/KOER 31: EVP circuit below minimum voltage of 0.24 volts.

1986 EB, 5.0, with AOD. Pretty much stock except for a remote trans filter and cooler.

Here’s what I’ve done…..

Tested and replaced bad EGR valve
Tested and repaired vacuum leaks
Preformed and passed leak down test
Tested and replaced EVP sensor. I actually had to go through 4 to get one that functioned properly (4500 ohms).
Preformed EVP circuit test (VREF & SIG RTN) as described in the Haynes manual (5.4 volts)
Performed and passed Solenoid checks (EGRC and EGRV)
Cleared all codes

I found this while searching on the web one day (Page 88-90)
http://books.google.com/books?id=V6...tion&sig=709k2TbUlM4gpEDvzgSrVzinn2A#PPA88,M1

I followed the instructions on page 88 and jumped the VREF and EVP signal terminals to try and get code 35….not luck so this means that the problem most likely lies within my wiring. Since I am getting 5.4 volts on the VREF I assume that wire is good, so I traced the EVP signal wire to the EEC in hopes that I would find it cut or damaged, but it looks good.
When I tested the EVP Signal and VREF I received 0.04 volts so I assume that is where the problem is.

I also tried to check the resistance between ECA pin 27 and pins, 40, 46, and 60 as described on page 89, but I must have performed the test wrong because I didn’t receive any resistance on any of the pins.


So my question is….what am I missing? What haven’t I done that I need to do?
Thanks:cry
 

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Great source of info books.google etc., I'd wait and see if Steve83 chimes in or give him a PM.

If you think you have repaired the problem then clear the code, however if it's re-occurring keep digging at it.

Good Luck ~ :thumbup
 

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Discussion Starter #3
Thnx.
I forgot to mention that I do erase my codes.
I really haven't been able to fully enjoy the Bronco yet because this code is effecting my MPG. I am getting like 5-7 on the highway.

Besides that, the truck runs good for being 22 years old. The only other issue it has is on a warm or cold start up, the RMP's drop after the initial start up to the point that it almosts stalls, but then corrects itself immediately. Hope that helps.
 

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T&J:
I think gas mileage is a given, we're all in the same boat with these vehicles in that they're not that great.

If your BKO is stalling at cold/warm start there is an OEM FORD idle procedure that WORKS and the PCM will re-learn it I know because my idle is the best it's been in 4 years.

Warm up the motor to normal operating temp, shut it off then disconnect your IAC, fire it back up and using the TB idle stop screw adjust the idle with your tach using Haynes for correct idle rpm. Re-connect and drive around a bit and the PCM will re-learn new idle setting, you're good to go. I would recommend eyeballing the positon of the screw first, then using chaulk to mark the screw for reference and count the number of turns.

I'm sure you'll hear not to mess with the screw, however one of the guys here said he worked for FOMOCO and that's the way they do it and Ford would not have spent the money for tool & die designing a litle screw with threaded hole that doesn't function, otherwise the would have just put a little fixed stud there instead.

Good Luck ~ :thumbup
 

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That's right, good call Ryan! :doh0715:

It sits right on top with a vacuum line, 3 screws and a rubber gasket available anywhere and affects the idle.

Good Luck ~ :thumbup
 

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Discussion Starter #7
Performed and passed Solenoid checks (EGRC and EGRV)
Thanks for the responses guys!

Are you saying I should retest the soleniods? I tested them as discribed in the Hanyes Manual.

Thanks
 

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Discussion Starter #9
I followed the instructions on page 88 and jumped the VREF and EVP signal terminals to try and get code 35….not luck so this means that the problem most likely lies within my wiring. Since I am getting 5.4 volts on the VREF I assume that wire is good, so I traced the EVP signal wire to the EEC in hopes that I would find it cut or damaged, but it looks good.
When I tested the EVP Signal and VREF I received 0.04 volts so I assume that is where the problem is.

Last plead for help.....:whiteflag

If the EVP signal wire is in good condition (no visual signs), why am I getting a poor reading on it? Is there another way to test that wire????

Should I try another EEC?
 

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Discussion Starter #10
Instead of starting a new thread I decided to post here again.

I am STILL getting KOEO/KOER 31 (EVP circuit below minimum voltage of 0.24 volts) and have done all the check's in the Haynes manual including an EEC swap. So the next suspect is the actual wiring. I want to make sure the wiring is good and there are no shorts. I have visually inspected the wiring and everything looks fine.

Today at the Junk Yard I scored a pristine wiring harness from a 86 F150, so I grabbed it for $19.99. I want to test the EVP wires before I install the new harness...

How do I do that?:shrug

I looked around here and on google and couldn't really find anything.

I assume I check for resistance of the wire on the sensor plug side and on the EEC harness side, but I don't know what normal....

Thanks
 
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