DIY KOEO/KOER/Cylinder Balance Self-Test

Ford EEC-IV/OBD-I Systems

By Joel5.0

Definitions:

Before we attempt to start any type of testing, the definitions of some acronyms are in order. This will help the electronic fuel injection (EFI) newbie start understanding the slang used.

KOEO = Key On Engine Off

KOER = Key On Engine Running

STO = Self-Test Output

STI = Self-Test Input or trigger wire to initiate self-test routines

CEL = Check Engine Light

MIL = Malfunction Indicator Light = CEL

ECM = Engine Control Module or computer

DLC = Data Link Connector

VIP = Vehicle Interface Port Connector = DLC

SIGRTN = SIGnal ReTurN or ground reference for sensors provided through ECM

EEC-IV = Electronic Engine Control IV generation or Ford's OBD-I system

OD Codes = On Demand Codes, this are the failures the system logs based on a real-time check, failure is present.

CM Codes = Continuous Memory Codes, this are the failure codes the system has logged and saved in memory based on a failure the system detected at one point in time.

R Codes = Engine Running Codes, this are the failure codes the system logs based on the KOER self-test routine.

OBD-I = On Board Diagnostics Rev. I

Tools/Equipment:

Analog VOM or 12-vdc Test Light

Paper Clip or piece of Jumper Wire

Pen and paper

Next...need to identify the VIP/DLC connector location. Using Ford Mustangs as reference, for '86-'93 models...it is located behind the LH/Driver side strut tower. For '94-'95 Mustangs, it is located behind the RH/Passenger side strut tower as shown below.

'86-'93 VIP/DLC Connector Location

'94-'95 VIP/DLC Connector Location

Now that the VIP/DLC connector has been found, check its terminals pin out diagram .

Now you are ready to setup the system to run the self-test. Place the jumper wire and the 12-vdc test light or AVOM as shown in the following diagram. Please note that if you have a functional CEL/MIL indicator, you could use it to count the flashing pattern for the codes.

Codes flashing/needle sweeping patterns comes in two flavors, ’86-’93 Mustangs, pre-’91 Fords follow a 2-digit pattern….SN95 Mustangs and post-’91 Fords follow a 3-digit pattern as shown below:

2-Digit Codes

3-Digit Codes

Codes Itemization:

OD or "O" Codes: These codes are the first set of codes flashed during the KOEO self-test. They are the codes displayed previous to the "10" separator code.

CM or "M": These codes are the ones flashed after the "10 Separator" during the KOEO self-test. These are codes the system logged during the previous 40 ignition cycles and were stored in memory.

R Codes: These codes are flashed after the Engine ID code (2 = 4 Cyl., 3 = 6 Cyl. and 4 = 8 Cyl.) in the KOER self-test.

It is important the codes get itemized to determine if they're "hard failures", intermittent or logged by operator error (operating the car with a sensor disconnected), since their definition may vary depending on the type of code. OK, let's run the self-tests.

Running a KOEO self-test:

Setup the VIP/DLC connector jumper as described above.
Turn Ignition On.
Count the flashing/needle-sweep pattern.
Write down the codes logged.
Start a topic with your problem in the Electronic Engine Management section.

Running a KOER self-test:

Setup the VIP/DLC connector jumper as described above.
Start the engine...make sure the gas pedal is not touched.
Watch for the Engine ID code to be flashed.
A this time the engine will increase idle speed, activate system actuators, check sensor inputs, idle will fluctuate, etc. The KOER routine usually takes 2-3 minutes to run, at the end of which the idle speed stabilizes and codes will start to flash.
Start counting the codes pattern.
Write down the codes logged.
Start a topic with your problem in the Electronic Engine Management section.

Running a Cylinder Balance self-test:

The cylinder balance test checks that all cylinders are producing the same amount of power. To do so the system will turn off each cylinder injector, record rpm loss and compare it to the other cylinders. This test can be done three times in a row, each time it is repeated after the first one, the rpm difference value to ID a passing/failing cylinder will be lower (stricter).

If a cylinder is shown as weak in the third test (provided you run it a third time), it should be considered non-contributing. The tests may be repeated as often as needed if the throttle is depressed within two minutes of the last code output. Subsequent tests, after the 3rd. cycle, will use the percentage from the third test instead of selecting even lower values.

Run a KOER self-test as described above and wait until all codes are flashed, DO NOT TURN ENGINE OFF.
Within 2 minutes of the last code output, do a brief WOT.
Engine rpms should raise and the test initiated.
The elapse time of this test is 2-4 minutes after which time....the codes will be output.
Write down the codes logged. (90 = PASS, 10 = Cyl. #1 Fail, 20 = Cyl. #2 Fail.......)
If a code 90 (System Pass) was obtained, repeat 2-5 for a 2nd. run and goto 7.
Start a topic with your problem in the Electronic Engine Management section.

Codes Definitions:

For the list of definitions for the failure codes obtained, follow the link to the SBFTech.com Engine Management section, if you need to do any troubleshooting to identify what is the cause for the code, you can go to the EEC-IV Troubleshooting Database at http://www.my5oh.com

Clearing EEC-IV Codes:

Disconnect battery (-) terminal for 3-5 minutes.
The above will cause a code 15 (Keep Alive Memory (KAM) Test Failed) to be logged since power was removed from the system memory.
To clear this code (or any other codes) you could also use the alternate/quick procedure, explained below.

Alternate Procedure to Clear Codes:

Setup the system to run a KOEO self-test.
Turn Ignition On.
As soon as the codes start to flash, disconnect the STI jumper wire.
Turn Ignition Off, set the system to run a KOEO self-test again, and confirm code 15 is cleared from memory (CM codes).

Troubleshooting Information and Repair Links:

The following list of links will help you troubleshoot or take care of typical Ford/Mustang related problems.

This article was made with the contributions and material provided/available by/at:

TENGRAM

VRIstang

Woody

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