85NA_Auto in limp home mode

  • #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.
  • #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
      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.
  • #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.

    Comment

    • dbruce
      #4.1
      dbruce commented
      07-05-2018, 09:59 AM
      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
  • #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
  • #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.
  • #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.
  • #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.