Koer Code 12???? Help!!!

flashback87 · Jun 25, 2014

Hey guys,

Can someone tell me what KOER code 12 is? I have been researhing but I'm not finding a lot of info on this code. From my research it sounds like it has something to with not being able to get my idle to 1500 rpm's during the koer test but what would be causing this.
I'm trying to track down a little idle surge before I start spening money on parts. I have been going through the surging idle checklist, so I cleaned my iac valve and tb. I keep running the codes and I have always gotten that one for koer. my idle is set at 750-800. I have a b cam, gt40p heads and indtake, maf conversion and no egr.

Thanks!

flashback87 · Jun 26, 2014

Anyone know how to fix this code?

Mustang5L5 · Jun 27, 2014

Not being able to raise idle might suggest that the IAC is opened to the max range at idle. So i would start by resetting the idle range, and then rerun the codes. In fact, if you were to unplug the IAC at idle and the engine stalls, that would confirm that.

If this is the case, you will want to perform the idle reset procedure

flashback87 · Jun 27, 2014

Mustang5L5 said:
Not being able to raise idle might suggest that the IAC is opened to the max range at idle. So i would start by resetting the idle range, and then rerun the codes. In fact, if you were to unplug the IAC at idle and the engine stalls, that would confirm that.

If this is the case, you will want to perform the idle reset procedure

Thanks for the reply! I have tried unplugging my IAC and the idle does not change. I am wondering if my IAC is done.

Thanks again!

Mustang5L5 · Jun 27, 2014

I'd perform a base idle reset first.
Locate the throttle stop screw on the side of the throttle body and turn it in to open up the blade slightly. Start the engine and unplug the IAC. Slowly back the throttle screw stop out to lower the idle. Drop it down as low as you can go to maintain a good, steady, reliable idle.
Then reset the computer by unplugging the battery for 30 mins. Plug the IAC back in and hoo the battry up and start the car and let it relearn idle. Drive it around a day or so...and then rerun the codes.

flashback87 · Jun 27, 2014

i did the idle reset as described above. the engine was warm and i disconnected the iac. i was able to move the idle set screw completely off the tb and it stayed idling at around 600 (stock tach). so i tightened it a little so it was opening it just a little. i disconnected battery and waited for about 2o minutes. I hooked every else back up and tried starting. it would crank but would not keep rpms up so i tightened the screw just a littl more. I got it to run and went for a short drive. It stalled a few time when clutch was pushed to put car in nuetral for a stop because rpm's fell too low but it was doing that less as i drove more. I was only able to drive it around the block for a minute or two but when i pulled in the car was idlig nicely at 700-750 rpms when warm (b cam). i will drive it more tomorrow and hopefully that will help it relearn everything and wont stall. i was not able to see if koer 12 was gone.

What do you think?

Thanks!

Mustang5L5 · Jun 30, 2014

Give it a day or two to relearn the idle...and then run the codes again once the idle is stable the the car stops stalling.

flashback87 · Jul 2, 2014

i did the base idle reset and replaced my iac and tb gaskets. still an idle surge and code 12. i was going to take it for a drive today but when i put it in first it stuttered the whole time i had my foot on the accelerator in every gear. so i went to the end of my street and came home.

could this be caused by a bad fuel filter? i replaced the filter about 6 yers ago but i have only put about 4-5,000 miles on it since then. but it sits for abou 4 months in my garage every winter.

The car has been running great since i put the explorer motor in 2 years ago. This just started a few weeks ago with a slight idle surge and now it is stuttering/bucking when i am driving it.

please let me know what you guys think.

Thanks!

Mustang5L5 · Jul 3, 2014

Is that still the only code you get?

jrichker · Jul 3, 2014

You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix.

It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 134,000 hits, which indicates it does help fix idle problems quickly and inexpensively.

flashback87 · Jul 3, 2014

Mustang5L5 said:
Is that still the only code you get?

I ran them last night and if I remember correclty i got, KOEO - some EGR code, i believe 34 (i have no egr) and 96 ( i did not wire in this in when I converted it to mass air
KOER 12 and 21 ( i ran codes when engine was cold)

Koer Code 12???? Help!!!

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