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  • Idle/TPS Adjustment Issues

    I've had some idling & firing probs, and done some work lately (new disty, vac hoses, plugs & wires, VCG's, etc) - now that I'm finished, I'm having trouble adjusting the Idle & TPS.

    - Started out with a really low idle (~300 rpm), idle screw did nada.
    - Adjusted TPS, got the idle up around 700-800.
    - It's still a little bouncy, but the problem is the A/C - when the compressor is on, the idle drops back down to ~300. Before I adjusted the TPS, turning on the A/C would push the rpms up from ~300 to ~500.

    I've been toying with the TPS, but I can't seem to get the rpms above 300 when the A/C is on. Things are fine with A/C off.

    Ideas?

    -js

  • #2
    adjust everything to where it should be. Then troubleshoot from there, close the idle screw. your IaC may have gone TU, or something may be obstructing the idle air passageway.
    RIP: Electric Blue '95 GT ZE RIP: Black '93 GT
    Currently rollin' 7.3L of TURBO POWA!!!!

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    • #3
      There is a wire connector under the TB that controls the IAC...If this is not plugged in completely the idle will not increase when the AC pump is actuated....

      Happened to me...I thought it was plugged in nice and tight...but it wasnt...gave it a little extra push and presto..problem solved...
      Rick_96PGT #62
      "I never apologize.
      I'm sorry, but that's just the way I am."
      - Homer J. Simpson

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      • #4
        I know, you wanted to hear more about my relentless idle problems...

        Latest with the TPS:
        Adjusting the TPS via the TEN/GND jumper & cooling fan technique gives me a really low idle (~200). Overturning it a bit (counter-clockwise) will get the idle up to a more reasonable level. However this only works with the engine warm.

        Question: Could this be a sign of a failing TPS? Or should I spend another week vacuum leak chasing?

        Or if you want to give a more thorough answer - What _exactly_ does the ECU do with TPS data? Is it simply used in conjunction with the VAF data to determine how much fuel to send, or are they used seperately?

        Thanks for the info so far, checked out the IAC harness & no luck.

        -johnny




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        • #5
          hm, did you try adjusting the TPS to where its supposed to idle at 650 (but idles at 200) and just turning the idle adjustment screw up so its at 650 at that point?
          1993 Ford Probe GT - KLDE + N2O
          228 whp 241 wtq - 2340 lb race weight
          ATX - 13.44@105.1 MTX - 13.35@106.1

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          • #6

            Yes, with the TPS adjusted properly, the idle screw has no effect. Strangely, with the TPS overturned (as I mentioned) the idle screw does as it should. Hmmm thinking about it that way makes a case for a bad TPS...

            -johnny

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            • #7
              js, dude i feel your pain. i'm having a heck of a time trying to adjust my tps with cooling fan trick. i'm convinced that this trick doesn't work for my car for whatever the reason. don't give up though, read up on julians method on his website using a voltmeter. this is actually the proper way of adjusting the tps anyway.
              http://www.bradbury.cwc.net/probemx/index.htm

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