No KOER codes

Donnie strickland · Nov 5, 2007

1994 4.0 5 speed 4WD Ranger --

I decided to check out an intermittent stumble and hooked up my tester to pull any codes. First I did the KOEO test and got:

522 -- vehicle in gear (it wasn't)

172 -- lean bank #1

173 -- rich bank #1

176 -- lean bank #2

177 -- rich bank #2

So far, so good. Then I drove about 10 miles and turned the motor off. Hooked up the tester and started the motor to do the KOER tests, and got -- nothing. I have checked the Haynes manual and Alldata site to make sure of my connections, and found nothing amiss. This occurs with a scan tool or a VOM; I tried both to make sure. Could this be a PCM problem?

MAKG · Nov 5, 2007

Forget the KOER test unless you get a pass for your KOEO test. I've seen the 2 digit equivalent of your 522 (a 67) cause the KOER test to refuse to run.

Lean codes CANNOT be KOEO. The engine isn't running, so how can the engine know if it's lean or rich? Be careful not to confuse KOEO codes with Continuous codes.

Check your neutral sensing switch. Should be closed in neutral.

Donnie strickland · Nov 5, 2007

MAKG, I bow to your superior knowledge. I did the KOEO test 6 times and got these codes every time -- which leads me to believe these are indeed continuous codes. But according to the manual I should get a separator code (single pulse) to signify that the continuous memory mode has been entered. I do not get a separator code whatsoever, either before or after the 522.

So will I not get any KOER codes until the 522 is fixed?

Donnie strickland · Nov 9, 2007

Got it. Fixed the 522, cleared the memory, but still no KOER codes. Had to replace the PCM. Now I get a 111 "system pass" on the KOER; I still get the same rich/lean codes in continuous memory -- but I do get a separator pulse now.

MAKG · Nov 12, 2007

Ford PCM's don't die. They get killed, usually circuit-by-circuit. So, I'd look for the intermittent short to ground that killed it. Not easy. But if you don't look, you may kill your new one in the same way.

Rich AND lean codes in the same bank at the same time suggest the HEGO sensor has an intermittent signal and/or ground wire.

Donnie strickland · Nov 12, 2007

MAKG said:
Ford PCM's don't die. They get killed, usually circuit-by-circuit. So, I'd look for the intermittent short to ground that killed it. Not easy. But if you don't look, you may kill your new one in the same way.

Rich AND lean codes in the same bank at the same time suggest the HEGO sensor has an intermittent signal and/or ground wire.

Noted, and previously checked. I agree. Actually Alldata says to check the fuel injectors first for these codes, but I checked the HEGOs first and found nothing unusual . Now it's on to the injectors.

bforum3 · Jan 19, 2008

help

Hey i have the same problem i get the same 522 code but cannot figure out how to fix it, ive been looking for the nuetral sensing switch but only found a connector by the transmission that isnt hooked to anything and there is no place to plug it, is there supposed to be a place to plug it in, or a plug and switch that just hangs there, i cant figure this out, and i know i have to replace my ecm cause i had a ground issue and it would kill my truck, so im guessing it killed my ecm. I beleive that i have an explorer motor in it so should i get an ecm from an explorer, and does it need to be the same year as the motor, cause i dont know what year the explorer motor came from.

fireguy12117 · Jan 19, 2008

I dunno about the KOEO codes specificaly, but i can attest to MAKG's comment about the computers getting killed. im finding bad wire after bad wire in the enine wiring harness which worries me about the rest of the body wiring- but explains why i had so many confusing intermitten problems in the past. never discount faulty wiring! IAC issues, idle issue, PCM got replaced because according to the shop "so many strange out of spec readings on the engine coolant sensor"....

bforum3 · Jan 19, 2008

i just need to know if i am suppose to plug the neutral sensing switch into something or if there is no place to plug it in, then can i make it think its plugged in.

Donnie strickland · Jan 19, 2008

After I replaced my PCM, I had to replace the neutral switch on the transmission; but before I replaced the neutral switch I was able to pull codes by temporarily jumping across the connector with a short length of wire to make the PCM think the truck was in neutral.

A bad battery ground cable can cause all sorts of electrical problems.

Kona · Jan 19, 2008

Yeah, great.. did you have a problem with your truck suddenly stopping running and then restarting after a second? (without human intervention ) Because I do, plus running rich and throwing codes but not storing them AND now run on on shut down. Where did you get a replacement PCM from?

Donnie strickland · Jan 19, 2008

I got a replacement PCM at Advance Auto Parts.

No, it never stopped running.

MAKG · Jan 20, 2008

Tripping codes but not storing them? Momentary loss of engine control? Sounds like the computer's power or ground is getting interrupted momentarily.

No KOER codes

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