Codes 33, 87 & 96 - 89 LX?

Discussion in 'Fox 5.0 Mustang Tech' started by KobraLX, Feb 10, 2011.

  1. So I was having problems with the 5.0 suddenly acting like, when it is cold, it was not getting enough fuel to start. Once started it would run although it was tripping the check engine light at about 3000 rpm on cold mornings (below 50) but going off once the throttle was released. Otherwise fine.

    Pulled codes 67 and memory codes 33, 87, and 96 with KOEO.

    Thought the fuel pump relay was the main culprit, as I have changed that, as I have before many moons/miles ago. Changed it the other night with no improvement.:(

    Next is a new EGR valve. Replacing tonight - if time allows.

    If still a problem, where next? Inertia switch? Fuel pump (got 1 yr on it)?

  2. Currently it is running. EGR made a noticeable improvemnt. Old EGR had some oil accumlation in it - not good but I hope to replace this 190,000 motor this year.
  3. Okay. Once again, problem is back.

    Intermittent cranking but not starting problem without insistant cranking and pressing the throttle. Appears to be more likely when the motor is cold/air is cold. Sounds if the fuel pump is pressurizing.

    Reran codes and got:

    Fast codes, 67, 67, 1, 33, 87, 96, 33, 87, 96

    Read up on 67 code. In neutral and the A/C is not engaged during KOEO.

  4. Ran with clutch in

    Ran the KOER test - twice
    4 - 21 - 94 - 33

    Reran KOEO

    11 - 11 - 11 - 33 - 87 - 96 - 33 - 87 - 96

    Cleared memory by removing self test

    11 - 11 - 11

    So how to I interpret that KOEO is showing no hard faults but now I have some new stuff in KOER
    21 ECT is bad
    94 AIR system inoperative
    33 EGR not working

    I can never find vacuum leaks on cars. TB cleaner sprayed around?
  5. Code 33 - Insufficient EGR flow detected.
    Look for vacuum leaks, cracked vacuum lines, failed EGR vacuum regulator. Check to see if you have 10” of vacuum at the EGR vacuum connection coming from the intake manifold. Look for electrical signal at the vacuum regulator solenoid valves located on the rear of the passenger side wheel well. Using a test light across the electrical connector, it should flicker as the electrical signal flickers. Remember that the computer does not source any power, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.
    Check for resistance between the brown/lt green wire on the EGR sensor and pin 27 on the computer: you should have less than 1.5 ohm.

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

    EGR test procedure courtesy of cjones

    to check the EGR valve:
    bring the engine to normal temp.

    connect a vacuum pump to the EGR Valve or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

    Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).

    apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

    if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.

    if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.

    if engine stumbled, connect EGR test jig to the hose coming off of the EGR Valve.
    Use your finger to cap the open port on the vacuum tee.
    snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
    did the vacuum gauge show about 2-5 in vacuum?
    if not the EVR has failed

    EGR test jig

    The operation of the EGR vacuum regulator can be checked by using a test light applied across the wiring connector. Jumper the computer into self test mode and turn the key on but do not start the engine. You will hear all the actuators (including the EVR vacuum regulator) cycle. Watch for the light to flicker: that means the computer has signaled the EGR vacuum regulator successfully.

    Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests. You can generally ignore this code, since it has no effect on engine performance.

    The computer wants to make sure the A/C is off due to the added load on the engine for the engine running tests. It also checks to see that the transmission is in Neutral and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

    The NSS code 67 can be bypassed for testing. You will need to temporarily ground computer pin 30 to the chassis. Computer pin 30 uses a Lt blue/yellow wire. Remove the passenger side kick panel and then remove the plastic cover from the computer wiring connector. Use a safety pin to probe the connector from the rear. Jumper the safety pin to the ground near the computer.
    Be sure to remove the jumper BEFORE attempting to drive the car!!!

    Code 87 – fuel pump primary circuit failure. The fuel pump lost power while the engine was running. Check fuel pump relay, check inertia switch, wiring to/from inertia switch, red wire going to inertia switch for +12volts. Check the other side of inertia switch for +12 volts.

    Diagram of the fuel pump wiring for 86-90 cars

    Diagram of the fuel pump wiring for 91-93 cars.

    Code 96 – KOEO- Fuel pump monitor circuit shows no power - Fuel pump relay or battery power feed was open - Power / Fuel Pump Circuits. The fuel pump lost power at some time while the ignition switch was in the run position.

    Look for a failing fuel pump relay, bad connections or broken wiring. The fuel pump relay is located under the Mass Air Meter on Fox bodied stangs built after 91. On earlier model cars is under the passenger seat. On Mass Air Conversions, the signal lead that tells the computer that the fuel pump has power may not have been wired correctly. See Mustang Mass Air Conversion «

    Diagram courtesy of Tmoss & Stang&2birds

    Look for power at the fuel pump - the fuel pump has a connector at the rear of the car with a pink/black wire and a black wire that goes to the fuel pump. The pink/black wire should be hot when the test connector is jumpered to the test position. . To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground.

    86-90 Models:
    Using the diagram, check the red/black wire from the fuel pump relay: you should see 12 volts or so. If not, check the inertia switch: on a hatch it is on the drivers side by the taillight. Look for a black rubber plug that pops out: if you don't find it, then loosen up the plastic trim. Check for voltage on both sides of the switch. If there is voltage on both sides, then check the Pink/black wire on the fuel pump relay: it is the power feed to the fuel pump. Good voltage there, then the fuel pump is the likely culprit since it is getting power. No voltage there, check the Orange/Lt blue wire, it is the power feed to the fuel pump relay & has a fuse link in it. Good voltage there & at the Pink/black wire, swap the relay.

  6. Sprayed TB cleaner around. No hits

    Air pump has a noticable wobble in the pulley. Bearings must be shot...
  7. jrichker, thanks for the info. Now I need to acquire a vacuum gauge, pump and test light.

    What the take on the ECT not showing anything until now? No codes in memory and not on the KOEO but on the KOER I find it.

    Same thing with the smog pump, how is it just now showing too? What's my options (cheap) for repairing it. Assume it might be hard to locate one in a junkyard now unless I got to one of the national Mustang speciality yards. My intentions were to start moving this car towards more of road race car at some point and I was going to ditch the smog pump at that time anyway. Although how do you get pass the code?

    So of the three current codes on the KOER what would be everyone's guess as to what is causing the intermittent cranking but not starting problem? Repeatedly tried it yesterday and it always started. I am in a real bind here as I have to get two kids, wife and myself to school/work and I am down to one vehicle.......:Damnit::bang:
  8. Was engine cold? Car will always show a code 21 unless engine is completely warmed up to operating temp.

    If not, you can unplug the ECT, and toss a DMM on the two prongs and measure resistance. There is a table around here somewhere showing temp to corresponding resistance values
  9. Well it SAID it was warm at the time. Is it possible the other two was false also due to warmth of the engine as I thought it was odd the KOEO kicked the 11 code?

    On a completely unrelated note, who is in your avatar? Has a Denise Milani look to her.
  10. I had that happen to me before. No code 21 with KOEO, but the running codes came back 21.

    Symptons were car hard to start when warm. Had to start it by pressing pedal to floor. Replaced sensor and it fixed that.

    There is a good resistance chart here somewhere to compare values to. I'm at work, so can't track it down ATM

    And yes...the girl is Denise Milani :)
  11. That's EXACTLY it. Run to NAPA and try and get a ECT.
  12. 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 RH 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 Mustang FAQ - Wiring & Engine Info

    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