Idle Problems.. new thread for problems

Discussion in 'Fox 5.0 Mustang Tech' started by savegoodautonfg, Jul 31, 2007.


  1. patrickmx2

    patrickmx2 New Member

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    YES. That in BOLD above is this:

    [​IMG]


    The "SOME CONNECTOR" you mention should be THIS below

    [​IMG]
    #81
  2. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    The computer pin 46 signal ground is a critical component: it provides ground for the TPS, ECT, EGR position sensor and ACT. Signal ground is used in many circuits that have analog inputs to isolate the electrical noise. It is always separate from power ground, although both may have a common connection origination point. Signal ground usually has some conditioning that reduces the electrical noise to prevent false readings
    The black/white wire (pin 46) is signal ground for the computer. It provides a dedicated ground for the EGR, Baro, ACT, ECT, & TPS sensors as well as the ground to put the computer into self test mode. If this ground is bad, none of the sensors mentioned will work properly. That will severely affect the car's performance. You will have hard starting, low power and drivability problems. What sometimes happens is that the test connector black/white wire gets jumpered to power which either burns up the wiring or burns the trace off the pc board inside the computer. That trace connects pins 46 to pins 40 & 60. Only an experienced electronics technician can open the computer up & repair the trace if it burns up and creates an open circuit.

    If the ground for the TPS goes bad, the TPS output voltage increases and the idle speed goes up.

    [​IMG]

    Troubleshooting signal ground problems:
    Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.
    1.) With the power off, measure the resistance between the computer test ground
    (black/white wire) on the self test connector and battery ground. You should see less than
    2.0 ohms.

    [​IMG]

    2.) MAP circuit: Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohms. Higher resistance than 1 ohms indicates a problem with the 10 pin connector or the splice inside the main harness where the wire from the 10 pin connectors joins the rest of the black/white wire. Next check the resistance between the black/white wire and the negative battery cable. It should be less than 2.0 ohms.

    3.) Engine mounted sensor circuit: Check the resistance between the black/white wire on the TPS and battery ground. It should be less than 2.0 ohms. Higher resistance than 2.0 ohms indicates a problem with the 10 pin connector or the splice inside the main harness where the wire from the 10 pin connectors joins the rest of the black/white wire.

    [​IMG]

    Attached Files:

    #82
  3. savegoodautonfg

    savegoodautonfg New Member

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    Well Jritcher, i already changed the fuel injector harness and as far as i know the ground was fine for a month or so didnt stick at all. just started again.

    jrithcer, do you think i should just try to run the new grounds like patrick said?
    #83
  4. patrickmx2

    patrickmx2 New Member

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    The fuel injector harness plugs into the "salt and pepper" shakers. So where in that replacement did you even touch the ground mentioned above?

    Unless you replaced the ENTIRE EEC harness you didn't touch the ground.
    #84
  5. savegoodautonfg

    savegoodautonfg New Member

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    The SIG-RTN wire??
    #85
  6. patrickmx2

    patrickmx2 New Member

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    Yes. The ground you might be thinking about on the rear of the intake is the HEGO ground.

    Go to www.fordfuelinjection.com and see if that helps you out any.

    And don't take this the wrong way because my intent is not to insult. If you are having this much trouble trying to grasp the concept of just taking two bolts and securing a simple $5.00 24" inch wire to the car you should really ask a friend to help you with this. The reason I say this is because after all the pictures, arrows and such you mentioned replacing a starter wire after calling it a ground.

    Again, I'm only looking out for you. Don't be insulted if I'm coming across wrong. I have some brilliant friends who are good at what they do for a living but know nothing about cars. At the same time I can't do their jobs as good as they can.

    Patrick.
    #86
  7. savegoodautonfg

    savegoodautonfg New Member

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    NO INSULT TAKEN. thank you patrick
    #87
  8. savegoodautonfg

    savegoodautonfg New Member

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    Update:

    I got into a situation last weekend and now because of it i'm broke. i have like 50 dollars to my name till i get paid next week.

    Now i didnt do the ground yet, im going to try to do it today. but it was sticking and i let it keep sticking and i got into my driveway and popped the hood, i disconnect IAC connector and it went down to normal and then reconnected it and it went back up to 2,000 sticking again, then i disconnect TPS connector and idle went back to normal then hooked back up the TPS and it went to 2,000 sticking again.

    What does this mean if anything?
    #88
  9. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    The TPS is sending the computer bad data. That means either the TPS is defective, or the signal ground I have been writing about is bad.
    #89
  10. savegoodautonfg

    savegoodautonfg New Member

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    I've tried so many TPS already including a BRAND NEW one. It must be the signal ground. if that is it how is that fixed?
    #90
  11. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Read my post #82 in this series of posts. It is 9 posts back up the page.
    #91
  12. savegoodautonfg

    savegoodautonfg New Member

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    I ran a ground 4ga wire from the power steering bracket thing to the chassis and i have had any sticking from throttle body in 4 days????
    #92
  13. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Power ground for the alternator and signal ground for the TPS (black/white wire connected to pin 46 on the computer) are not the same thing.
    #93
  14. savegoodautonfg

    savegoodautonfg New Member

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    Well its strange because since i did that i havent had sticking in almost a week
    #94
  15. savegoodautonfg

    savegoodautonfg New Member

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    #95
  16. fastford91

    fastford91 New Member

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    THIS SOUNDS LIKE SPAMING TO ME!!! ILL HELP YOU FIX IT BUT IT'LL COST YA! THIS SIGHT IS ABOUT HELPING ONE ANOTHER WITH AS LITTLE OR NO COST AT ALL! WE DONT TRY TO MAKE MONEY OFF OF EACHOTHER PAL! THE REASON IM WRITING THIS IS BECAUSE I HAVE SEEN HIS POSTS IN ACOUPLE OTHER PLACES TONIGHT AND GUYS LIKE THIS **** ME OFF!!! SOMONE BAN HIS ASS!!!:ban:
    #96
  17. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    #97
  18. BlownFiveLiter

    BlownFiveLiter have car, will race....wait, it doesn't run

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    You're right, and I did. You're welcome :nice:

    Please tone down the language though...
    #98
  19. savegoodautonfg

    savegoodautonfg New Member

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    You happen to have a picture?
    #99
  20. savegoodautonfg

    savegoodautonfg New Member

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