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85NA_Auto in limp home mode

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  • #1

    85NA_Auto in limp home mode

    starts fine, idles and warms up fine ... but no rev beyond 2K

    ECU reference: http://xenonzcar.com/z31/ECUcodes.html

    So long story short .. I ran ECU diagnostics and have two codes
    23 - throttle valve switch (idle switch ) circuit
    31 - load signal switch

    After checking the Auxiliary driving lamps aren't working at all so that is probably the 31 . I'm going to try swappin in another relay and see if that helps the fuse was OK ... hmmm

    I have a spare TPS so I'm going to try that tomorrow ( Its not perfect , it has a dead spot on the throttle rheostat deal )
    Last edited by dbruce; 07-02-2018, 06:45 PM.
    Tags: None
  • #2
    I seem to remember that the limp mode 2K limit was more often than not, caused by a faulty AFM.

    Might unplug it and try to start it to see if anything changes or at least throws that code. Just purely a guess.


    84 AE/Shiro #683/Shiro #820/84 Turbo

    Comment

    • Dunkine
      #2.1
      Dunkine commented
      07-02-2018, 08:35 PM
      Editing a comment
      Or the wiring / plug for the MAF. Connectors can get funky.
  • #3
    Thanks for the ideas .. I've seen lots of variations of this problem and right, bad wiring connections and bad power can make all this happen . Sometimes it is a bad component . When things go back and forth between working and not, I tend to think its a bad connection. I remember once I had a bad coil wire that was arcing and it acted just like this ... so it's not my first rodeo ... It's always the last place you look where you find the problem .
    I'm checking fuses and connections and I've got some spare pieces to swap ...
    Last edited by dbruce; 07-02-2018, 09:24 PM.

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    • #4
      So today it rev'ed fine ... took it for a drive and now waiting to see if it survives a thermal cycle ... hmmm ... bizarre
      Last edited by dbruce; 07-03-2018, 02:16 PM.

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      • dbruce
        #4.1
        dbruce commented
        07-05-2018, 09:59 AM
        Editing a comment
        as an aside I looked at my spare tps and it wasn't showing idle sw (short) . So after spraying with contact cleaner and blowing with air, the idle switch and the throttle ohms readings are now good ...
    • #5
      So today it's reving fine and I've started the engine multiple times and heat cycled the car ...
      So I must of cleaned the bad connection ( wish I knew which one )
      Now of course is the question of reliability, repeatably ... dependability
      I've got more new parts on the way ... and i'll check more bits ...
      • 1 like

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      • #6

        She lives ... again
        https://www.youtube.com/watch?v=tSukMQHQLIs The Sword Has Been Drawn

        Last edited by dbruce; 07-08-2018, 03:35 PM.
        • 1 like

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        • #7
          So far it seems to be fixed .... installed a new coil and TPS ,,, may have been water condensation around the spark plugs? Whatever ... Got new tires put on last week ( man the mich pilots were great 80K+ miles) and I'm proceeding with the tuneup ...
          Last edited by dbruce; 07-16-2018, 10:23 AM.

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          • #8
            Today I put in a new fuel filter , dist cap and rotor , and added an auto trans inline filter ... Adding in some Auto-rx to the auto trans to see if it un-stick the solenoids ( temp sensor, kickdown, lockup inhibit switch aren't working consistently see: https://www.auto-rx.com/for-dirt-con...rasives-sludge ) but shifts fine ... so maybe its the wiring again

            Last week I discarded the no tread Michelin Pilots ( 80K miles ) for these less expensive tires ...
            SUMITOMO HTR A/S P02 (H- OR V-SPEED RATED)High Performance All-Season
            • Size: 215/60R15 94H Serv. Desc: 94H
            Last edited by dbruce; 07-22-2018, 12:11 AM.

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            • #9
              FYI ... Today the AT lockup inhibit switch started working again ... E4N71B This takes you out of overdrive in all the gears 1-2-3 and out of TC lockup ...

              Also install the prw2 for the ignition yesterday

              So I don't know why maybe the AUto-RX is working or just that I've been driving it ( I took a long drive just yesterday ,,, and it would not work for me.) ... time will tell
              Last edited by dbruce; 08-03-2018, 04:42 PM.

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