Codes - Mustang Says...

Discussion in 'Fox 5.0 Mustang Tech' started by Strype, Jun 28, 2013.

  1. Car runs like crap until warm. Battery was disconnected but I plugged back up and ran the codes anyway... I have just replaced the IAB and TPS.

    I changed the ECT just in case, changed dizzy cap and rotor button, set the TPS to .98. I did the diagnostic again. This time I got results.


    21 ECT
    41 Passenger O2 Lean
    91 Driver O2 Lean
    33 No EGR (duh)
    18 SPOut circuit open
    13 Idle too high

    I revved to 3,000 RPM


    Which I'm guessing is Cylinder 2 didn't pass the balance test?
    Much thanks to:
    Of which was thanked.

  2. code 4? sure it isnt 14 for pip or 44 for smog? 21 is because the car isnt warmed up for the koeo or koer tests.

    running problems seem to lead to the dizzy.
    Strype likes this.
  3. Drat that blasted dizzy :fuss:

    Tomorrow I will replace it for the 3rd time. I need to buy a nice one instead of relying on autozone.

    Code 4? Dunno here's what she said-


    Then I turned it on and got the 8 cyl 4
  4. I'm going with

    14 - Profile Ignition Pickup Circuit Failure (CM)

    Dizzy indeed. Bless you sir. Bless you.

  5. ? does not make sense. every foxbody i have pulled codes on throw a short pulse of codes and then throws the engine codes, usually starting with 11 then all the rest of them. are you missing a blink somewhere in there? i would disconnect the battery and clear the codes and run them again before i did anything. and.... jrichker
  6. My eyes stayed glued to it. Second time I've done it. No wierd codes starting out. Also, I read somewhere that after 1991 the cars all went to 3 digit codes?

    It was the last 1993 coupe on the lot when my friend bought it. Sitting all alone surrounded by ugly 94's. Bless it. I'll try again tomorrow I guess!
  7. Negative. That 93 spits two digit codes.

  8. fugly 94's is right! what a disappointment those things were to the mustang faithful when ford aborted them onto the dealers lots.
  9. The PIP doesn't make sense. The car would die, not buck while cold. Hmmm
  10. If the 94's ever grew on me I'd have them surgically removed. :p

    When we were building this car, we had a rod that was too long, which is worse than a short one you can shim. We couldn't do crap with it so I traded out with my friend for a slightly shorter one than the rest. I am BETTING that it's that damned rod. Think about it, metal expands when warm... I mean it was within a shim or 2.

    Either that or maybe I'm a shim off on a cylinder. Sounds like a dead miss until warm.
  11. Yet you have engine codes and I assume the car was running and now is having problems
  12. Code 23.... The tps range need to be between .6 and 1.1. Tps Needs a small tweak to get it into the range and not sitting on 1.1 which will trigger a tps fault code.

    Code 18 needs investigating. I don't have input but this could potentially be a major issue

    Code 21. You said you took the sensor off? So you are running no ECT sensor? We are talking about the one that screws into the metal heater pipe and not the gauge cluster temp sensor in the intake manifold. The one in the heater pipe is for the EEC and needs to be in place. Running without an ECT can cause your car to run badly.

    Also, if you run the test with the car not warmed up, you can get a false cose 21. Car needs to be up to temperature
  13. Code 18 - SPOUT out or wiring fault - look for short to ground in SPOUT wiring going
    back to the computer. Possible bad TFI or defective 22 K resistor in the IDM wiring

    This code can disable spark advance and reduce power and fuel economy.

    Remove the passenger side kick panel and disconnect the computer connector.
    There is a 10 MM bolt that holds it in place.
    Disconnect the TFI module connector from the TFI and the measure the resistance between the yellow/lt green wire and ground.
    You should see greater than 100 K (100000) ohms.
    Check the resistance from Pin 4 on the computer connector (dark green/yellow) and the dark green/yellow wire on the TFI connector. You should see 20-24 K Ohms (20,000-24,0000 ohms). The resistor is located in the wiring harness about 6” from the connector. You will need solder and heat shrink to replace the resistor if it is bad.
    Next measure the resistance between the yellow/lt green wire on the TFI module connector and
    Pin 36 on the computer connector. With the SPOUT plug in place, you should see less than 2 ohms.

    The following is a view from the computer side of the computer connector.

    This diagram is the wire side of the computer connector.

    Diagram courtesy of Tmoss & Stang&2birds


    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 ECT 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.

    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.


    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


    See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
    (website host) for help on 88-95 wiring

    Ignition switch wiring

    Fuel, alternator, A/C and ignition wiring

    Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs

    Vacuum diagram 89-93 Mustangs
  14. Okay thanks j I'll check that out

    What's a "major" issue... :(

    ECT- I thought it was to the gauge. What heater pipe? We took a/c off to build motor. Stoopid me.
  15. steel pipe that runs above the passenger valve cover (3/8 or 1/2 inch diameter roughly). ect screws into it with a two wire connector off the harness there. it is a coolant/antifreeze pipe.
  16. You know it's awfully strange that when running it didn't repeat codes. Here's what I have written down while running. May you guys can make sense of it:

    KOEO - 85 1 4 4
    Then I turned it on
    Running - 4 2 1 *engine idled up* 9 *pause* 3 3 1 8 2 3 *engine idled up* 9 *pause* 3 3 1 7 4 4 2 *nothing*

    So my guess is that I didnt give it long enough in between KOEO and I never took the key out. So here's what I'm thinking:

    KOEO 85 14 4 *interrupted* *ignition on* 4 (8 cyl) 21 *cyl balance test* 90 33 18 23 *cyl balance test* 90 33 17 44 2?

    or that last part could be 93 31 74 42. Yeesh. I'll do it again when I get the chance. Probably tonight when it's dark.
  17. Dear lord. Post a video of it now its driving me crazy.

  18. Found it! Looks old but it's connected

  19. :lol: As soon as the stupid combines get done across the street. The dust is unbearable! Then we gotta take the boys to a kid's carnival.
  20. OK! I got the little flashes at the beginning this time. Now I know what that beeping is going down the road. It's irratic and odd. My CEL must be hosed. Here's what I got just now KOEO...

    85 85 14 14

    Then the beeping started and nothing else from the CEL. So I will have to use the volt meter I guess.