A Little Help Needed With Codes....

LILCBRA

I wish I didn't have all of these balls in the air
15 Year Member
Dec 6, 2005
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Marietta, Ga
We finally got around to getting codes from our 87 vert tonight and need a little help deciphering them to figure out what's going on. As I posted a while back, it dies suddenly while driving or when it's warmed up, like it was running out of fuel or spark. So, before we ran codes, we replaced the fuel pump and the TFI module. The pump was an upgrade since the future plan for the car may or may not require a larger capacity pump than stock. The funny thing was that the tank had been dropped before. I can't say that the pump was replaced or if it were still the stock pump as we found an old sending unit in the bottom of the tank. We fished that out and went on our merry way installing the new pump. The TFI module was a cheap and easy solution to try since the car appears to be more or less all original, so we figured it wouldn't hurt to try it. Needless to say, neither solved the problem. So, since I don't have a test light around, I bought a new one today and attempted running codes. We attempted the KOEO test twice and the KOER test once. All sets of testing gave a weird bulb flash at the very beginning? The bulb would flash dimly 2 or 3 times relatively quickly in succession, then proceed with "normal" flashing. Here are the numbers that we come up with without the quick dim flashes:

KOEO
1 6 7 8 2 6 7 8 2 1 1 4 1 4

KOER
4 1 2 2 1 4 2 9 2 2 1 4 2 9 2

We looked up a chart to decipher codes, but come up a little short with everything since there are a couple of different codes that they could lead to whether some are 2 digit or 3. With the KOER test, I noticed an occasional longer pause between flashes-I'm guessing that indicates a break in the reading? I didn't notice them all the time though. We can try to run the codes again in a little while and try to pay more attention to the length of pauses if need be, but can anyone help decipher these? Nearest I can tell is that the temperature sensor may be bad and possibly the PIP? Anyway, your help is greatly appreciated!!
 
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Your best bet is a code reader with an LCD display. I have one and I highly recommend it as an important and worthwhile tool. For a nice scanner see www.midwayautosupply.com/Equus-Digital-Ford-Code-Reader/dp/B000EW0KHW Equus - Digital Ford Code Reader 3145.
It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $22-$36.

You can also order them from Walmart for $24. See http://www.walmart.com/ip/41280661?...41544489&wl4=&wl5=pla&wl6=98369037609&veh=sem

Sears has it too, cost is $24.40, it probably will be an item that you have to order. See http://www.sears.com/equus-products...gclid=CM3d7r6KsMwCFRMlgQodbu0Olw&gclsrc=aw.ds


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Back to what you have...

It looks like you got 16, 78, 26, 78, 21, 14, 14 for the Key On Engine Off (KOEO) codes.

Code 16 - Electronic ignition - IDM circuit fault - Ignition Systems. Bad wiring, possible bad TFI. The computer isn’t seeing the proper IDM signal coming from the TFI circuit. There is a 22,000 ohm resistor in the dark green/ yellow wire that goes to pin 4 on the computer. Disconnect the TFI connector and remove the passenger side kick panel. Then loosen the 10 MM bolt to disconnect the computer connector. Use an ohmmeter to measure the resistance between pin 4 and the dark green/ yellow wire on the TFI connector. You should see 21 - 23 K ohms (21,000-23,000 ohms). If not the dark green/ yellow wire is broken or has a bad connection. If this checks out OK, measure between the dark green/ yellow wire and ground. You should see 1 M Ohm or more, OR an infinite reading. Less that 100 K ohms means a short to ground somewhere in the dark green/ yellow wire.
Wiggle and Jiggle the TFI wiring harness while testing it to help find breaks and short circuits in the wiring.


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Diagram courtesy of Tmoss & Stang&2birds

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
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Code 78 There is no valid code 78 definition for code 78 in 5.0 Fox body Mustangs. See Ford Fuel Injection & Electronic Engine Control 1988-1993 Charles Probst :ISBN 0-8376-0301-3. The Chilton manual for 1989-1992 Mustangs doesn't have one either. However, it could point to a problem with either the ignition switch or the computer power relay; in which case the engine would not run. If the engine does run consistently, then the code 78 is an unknown value or a misread of the code


Code 26 - Mass Air Flow out of range – MAF
There are three parts in a MAF: the heater, the sensor element and the amplifier. The heater heats the MAF sensor element causing the resistance to increase. The amplifier buffers the MAF output signal and has a resistor that is laser trimmed to provide an output range compatible with the computer's load tables.

The MAF element is secured by 2 screws & has 1 wiring connector. To clean the element, remove it from the MAF housing and spray it down with electronic parts cleaner or non-inflammable brake parts cleaner (same stuff in a bigger can and cheaper too).

Look for 12 volts across pins A & B.

The MAF output varies with RPM which causes the airflow to increase or decease. The increase of air across the MAF sensor element causes it to cool, allowing more voltage to pass and telling the computer to increase the fuel flow. A decrease in airflow causes the MAF sensor element to get warmer, decreasing the voltage and reducing the fuel flow. Measure the MAF output at pins C & D on the MAF connector (dark blue/orange and tan/light blue) or at pins 50 & 9 on the computer.

At idle = approximately .6 volt
20 MPH = approximately 1.10 volt
40 MPH = approximately 1.70 volt
60 MPH = approximately 2.10 volt

Check the resistance of the MAF signal wiring. Pin D on the MAF and pin 50 on the computer (dark blue/orange wire) should be less than 2 ohms. Pin C on the MAF and pin 9 on the computer (tan/light blue wire) should be less than 2 ohms.

There should be a minimum of 10K ohms between either pin C or D on the MAF and ground.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif


Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor.
Note that that if the outside air temp is below 50 degrees F that the test for the ECT can be in error. Warm the engine up until you get good hot air from the heater and then dump the codes again.

The computer Engine Coolant Temperature sensor has absolutely nothing to do with the temperature gauge. They are different animals. The ECT sensor is normally located it the passenger side front of the engine in the water feed tubes for the heater. It has two wires that connect by a weathertight plastic connector.

The water temperature sender for the temp gauge is located in the driver's side lower intake manifold. It has a single wire that connects by a push on connector on the temp sender.
The ACT & ECT have the same thermistor, so the table values are the same

ACT & ECT test data:

Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate readings.

Pin 7 on the computer - ECT signal in. At 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. At 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer.
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Voltages may be measured across the ECT/ACT by probing the connector from the rear. A pair of safety pins may be helpful in doing this. Use care in doing it so that you don't damage the wiring or connector.

Here's the table :

50 degrees F = 3.52 v
68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.

50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms

Diagram courtesy of Tmoss & Stang&2birds

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Code 14 - Ignition pickup (PIP) was erratic – the Hall Effect sensor in the distributor is failing. Bad sensor, bad wiring, dirty contacts. Factory tach will sometimes read erratically.

Revised 10-Dec-2012 to add PIP diagnostic testing & Wells info

The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. They are often heat sensitive, increasing the failure rate as the temperature increases.

PIP Sensor functionality, testing and replacement:
The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. A failing PIP sensor will often set code 14 in the computer. They are often heat sensitive, increasing the failure rate as the temperature increases.

Some simple checks to do before replacing the PIP sensor or distributor:
You will need a Multimeter or DVM with good batteries: test or replace them before you get started.. You may also need some extra 16-18 gauge wire to extend the length of the meter’s test leads.
Visual check first: look for chaffed or damaged wiring and loose connector pins in the TFI harness connector.
Check the IDM wiring – dark green/yellow wire from the TFI module to pin 4 on the computer. There is a 22K Ohm resistor in the wiring between the TFI and the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 22,000 ohms +/- 10%.
Check the PIP wiring - dark blue from the TFI module to pin 56 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the SPOUT wiring – yellow/lt green from the TFI module to pin 36 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the black/orange wire from the TFI module to pin 16 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the red/green wire; it should have a steady 12-13 volts with the ignition switch on and the engine not running.
Check the red/blue wire; it should have a steady 12-13 volts with the ignition switch in Start and the engine not running. Watch out for the fan blades when you do this test, since the engine will be cranking.
If you do not find any chaffed or broken wires, high resistance connections or loose pins in the wiring harness, replace the PIP sensor or the distributor.

The PIP sensor is mounted in the bottom of the distributor under the shutter wheel. In stock Ford distributors, you have to press the gear off the distributor shaft to get access to it to replace it. Most guys just end up replacing the distributor with a reman unit for about $75 exchange

PIP problems & diagnostic info
Spark with the SPOUT out, but not with the SPOUT in suggests a PIP problem. The PIP signal level needs to be above 6.5 volts to trigger the computer, but only needs to be 5.75 volts to trigger the TFI module. Hence with a weak PIP signal, and the SPOUT out, you could get spark but no injector pulse. You will need an oscilloscope or graphing DVM to measure the output voltage since it is not a straight DC voltage.

See http://www.wellsmfgcorp.com/pdf/counterp_v8_i2_2004.pdf and http://www.wellsmfgcorp.com/pdf/counterp_v8_i3_2004.pdf for verification of this little detail from Wells, a manufacturer of TFI modules and ignition system products.


Now for the engine running codes - Key On, Engine Running (KOER)

4 1 2 2 1 4 2 9 2 2 1 4 2 9 2


Code 4 - identifies the computer as being for an 8 cylinder car

Code 12 -Idle Air Bypass motor not controlling idle properly (generally idle too low) - IAB dirty or not working. Clean the electrical contacts with non flammable brake parts cleaner at the same time.

IAC doesn't work: look for +12 volts at the IAC red wire. Then check for continuity between the white/lt blue wire and pin 21 on the computer. The IAC connector contacts will sometimes corrode and make the IAC not work. The red wire on the IAC is always hot with the engine in run mode. The computer provides a ground for the current for the IAC. It switches the ground on and off, making a square wave with a varying duty cycle. A normal square wave would be on for 50% of the time and off for 50% of the time. When the idle speed is low, the duty cycle increases more than 50% to open the IAC more. When the engine speed is high, it decreases the duty cycle to less than 50% to close the IAC. An old-fashioned dwell meter can be used to check the change: I haven’t tried it personally, but it should work. In theory, it should read ½ scale of whatever range you set it on with a 50% duty cycle. An Oscilloscope is even better if you can find someone who has one and will help.

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Recommended procedure for cleaning the IAC/IAB:
Conventional cleaning methods like throttle body cleaner aren’t very effective. The best method is a soak type cleaner used for carburetors. If you are into fixing motorcycles, jet skis, snowmobiles or anything else with a small carburetor, you probably have used the one gallon soak cleaners like Gunk or Berryman. One of the two should be available at your local auto parts store for $22-$29. Take the solenoid off the body and set it aside: the carb cleaner will damage some types of plastic parts. Soak the metal body in the carb cleaner overnight. There is a basket to set the parts in while they are soaking. When you finish soaking overnight, twist the stem of the IAB/IAC that sticks out while the blocker valve is seated. This removes any leftover deposits from the blocker valve seat. Rinse the part off with water and blow it dry with compressed air. The IAC/IAB should seal up nicely now. Once it has dried, try blowing through the bottom hole and it should block the air flow. Reassemble and reinstall to check it out.

Gunk Dip type carb & parts soaker:
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Setting the base idle speed:
First of all, the idle needs to be adjusted to where the speed is at or below 600 RPM with the IAC disconnected. If you have a wild cam, you may have to raise this figure 100-150 RPM or so. Then the electrical signal through the IAC can vary the airflow through it under computer control. Remember that the IAC can only add air to increase the base idle speed set by the mechanical adjustment. The 600 RPM base idle speed is what you have after the mechanical adjustment. The IAC increases that speed by supplying more air under computer control to raise the RPM’s to 650-725 RPM’s. This figure will increase if you have a wild cam, and may end up between 800-950 RPM

Remember that changing the mechanical idle speed adjustment changes the TPS setting too.

This isn't the method Ford uses, but it does work. Do not attempt to set the idle speed until you have fixed all the codes and are sure that there are no vacuum leaks.

Disconnect the battery negative terminal and turn the headlights on. Leave the battery negative terminal disconnected for 5 minutes or so. Then turn the headlights off and reconnect the battery. This erases the computer settings that may affect idle performance.

Warm the engine up to operating temperature, place the transmission in neutral, and set the parking brake. Turn off lights, A/C, all unnecessary electrical loads. Disconnect the IAC electrical connector. Remove the SPOUT plug. This will lock the ignition timing so that the computer won't change the spark advance, which changes the idle speed. Note the engine RPM: use the mechanical adjustment screw under the throttle body to raise or lower the RPM until you get the 600 RPM mark +/- 25 RPM. A wild cam may make it necessary to increase the 600 RPM figure to 700 RPM or possibly a little more to get a stable idle speed.
Changing the mechanical adjustment changes the TPS, so you will need to set it.

When you are satisfied with the results, turn off the engine, and re-install the SPOUT and reconnect the IAC. The engine should idle with the range of 650-750 RPM without the A/C on or extra electrical loads. A wild cam may make this figure somewhat higher.

An engine that whose idle speed cannot be set at 600 RPM with the IAC disconnected has mechanical problems. Vacuum leaks are the #1 suspect in this case. A vacuum gauge will help pinpoint both vacuum leaks and improperly adjusted valves. A sticking valve or one adjusted too tight will cause low vacuum and a 5"-8" sweep every time the bad cylinder comes up on compression stroke. An extreme cam can make the 600 RPM set point difficult to set. Contact your cam supplier or manufacturer to get information on idle speed and quality


Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT sensor.
Note that that if the outside air temp is below 50 degrees F that the test for the ECT can be in error. Warm the engine up until you get good hot air from the heater and then dump the codes again.
See the previous code 21 definition I posted.

Code 42 & 92 (engine running) System rich - Fuel control or (memory) System was rich for 15 seconds or more (no HO2S switching) - Fuel control. Look for leaking injectors, fuel pressure too high, cylinder(s) not firing due to bad ignition.
Code 42 is the RH side sensor,
Code 92 is the LH side sensor.

The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.

When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

Testing the O2 sensors 87-93 5.0 Mustangs
Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear.


Backside view of the computer wiring connector:
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87-90 5.0 Mustangs:
Computer pin 43 Dark blue/Lt green – LH O2 sensor
Computer pin 29 Dark Green/Pink – RH O2 sensor
The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.

91-93 5.0 Mustangs:
Computer pin 43 Red/Black – LH O2 sensor
Computer pin 29 Gray/Lt blue – RH O2 sensor
The computer pins are 29 (LH O2 with a Gray/Lt blue wire) and 43 (RH O2 with a Red/Black wire). Use the ground next to the computer to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.


Testing the O2 sensors 94-95 5.0 Mustangs
Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear. The computer pins are 29 (LH O2 with a red/black wire) and 27 (RH O2 with a gray/lt blue wire). Use pin 32 (gray/red wire) to ground the voltmeter. The O2 sensor voltage should switch between .2-.9 volt at idle.


There is a fuse link for the O2 sensor heater power. According to Ranchero50, it is in the wiring near the passenger side hood hinge. Measuring the voltages will give a clue if it has shorted to the O2 sensor signal lead. The O2 sensor voltage should switch between .2-.9 volt at idle.
 
Thanks jrichker, I will look into some of the checks you posted tomorrow! I was also thinking of the reader earlier, I may go ahead and spring for it to eliminate any confusion about the codes.

I've been looking at the numbers I posted and referencing this chart (http://www.fiveohinfo.com/fox/eec.php) in different combinations for a little bit, and here is what I come up with so far:

* indicates what I believe to be the case while deciphering

KOEO: 167 82 67 82 114 14

16 - Erratic idle, oxygen sensor out of range or throttle not closing (running)
*167 - Insufficient Throttle Position change during Dynamic Response Test (running)

78 - power circuit 1 (memory)
*82 - Thermactor air circuit, integrated controller circuit (KO)

*67 - No Mass Air Flow sensor signal (N/A) , Neutral drive switch or circuit (KO, running, memory) , *Air conditioner clutch switch circuit (memory)

*82 - Thermactor air circuit, integrated controller circuit (KO)

11 - System OK, testing complete
*114 - Air Charge Temp (ACT) out of self test range (KO, running)

*14 - Ignition profile pickup erratic (KO, memory)


KOER: 412 21 42 92 21 42 92

41 - Oxygen sensor signal (memory) , Lean fuel mixture (running)
*412 - Cannot control rpm during KOER high rpm check (running)

22 - MAP sensor out of specified range (KO, running, memory)
*21 - Coolant temperature sensor out of specified range (KO, running, memory)
214 - Cylinder Identification (CID) circuit failure (memory)

14 - Ignition profile pickup erratic (KO, memory)
*42 - Fuel mixture rich (running, memory)

29 - No continuity In Vehicle Speed Sensor circuit (memory)
*92 - Fuel mixture rich, fuel pressure high (running)

22 - MAP sensor out of specified range (KO, running, memory)
*21 - Coolant temperature sensor out of specified range (KO, running, memory)
214 - Cylinder Identification (CID) circuit failure (memory)

*42 - Fuel mixture rich (running, memory)

*92 - Fuel mixture rich, fuel pressure high (running)
 
Thanks for the help jrichker! That's exactly what I did!! I went and bought a code reader at Autozone to eliminate the deciphering of flashes. Here is what the reader gave me a little bit ago:

KOEO
82, 67, 82, 10, 14

KOER
21, 42, 92, 21, 42, 92

So, the book that comes with the manual says this:
82 - Air diverter solenoid circuit fault
67 - Neutral drive switch circuit failure, circuit open; or A/C input high
10 - Doesn't list it
14 - PIP circuit failure (I believe I've found the major issue!)

21 - Cooling temperature sensor or ECT out of range
42 - HEGO sensor voltage high/always rich
92 - HEGO sensor voltage high/system rich

So..... it looks like I'll be pulling the distributor! Now the debate on whether to just replace the PIP or upgrade to a new distributor like an MSD. Does anyone have any suggestions either way or recommendations on a good aftermarket distributor? The plan as it sits right now is to install a set of Explorer GT40 3 bar iron heads (already have them sitting here with new springs installed and ready to go), Explorer GT40 intake, headers, MAF and maybe a cam and/or 1.7 rockers. We are leaning toward a new distributor, but would like a little input. Thanks!!
 
A little update with this. We decided to buy a Summit brand distributor since we are close enough to a Summit showroom and no one close had a distributor in stock. I had some other things to buy anyway plus I haven't had a chance to visit there yet, so it was a day well spent! It appears to be a pretty solid unit, but I've read a few different posts to the contrary. We went ahead and installed it the other day, but haven't had a chance to take it on a test run. As it sits right now, we set the timing to about 12* BTDC. It runs pretty well at idle as well as giving it some throttle while in neutral. I'm hopeful that we'll be able to give it a little test run this week and dump any new codes it may still have. One thing we did find while replacing the distributor was that the temperature sending unit connection has been tampered with. It is a crimped on O style connector that wasn't held down by a nut. There was a nut laying on the manifold, but it didn't appear to be the same thread as the sensor. Gotta love previous owners!! So, I'm guessing that maybe someone tried to hot rod the intake somehow, then thew the original back on and sold it, possibly knowing about the hot-dying condition and either not wanting to throw more money at it or didn't know what to do. Oh well, it's getting some much needed love now!! :)