86T NA-T Nistune ~2500RPM lean spike issue

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  • #1

    86T NA-T Nistune ~2500RPM lean spike issue

    I have been dealing with this for a few months now, talking to Matt off and on, wondering if anyone else has seen this. idle, fine, accelerating, AFR's fine, hit 2200-2600 RPM or so and it just pegs lean AFR's, stumbles, adn I hear the turbo spooling, but not accelerating, until past the RPM point (with some momentum already) and it will kick right back to proper AFR's and accelerate excellently!

    I have had the ROM chip reflashed at AutoVaughn performance… to no change.

    setup -
    Nistune Type 1 in an 87 NA ECU.
    NA-T VG30E stock internals, except for Jim Wolfe springs, and Isky cams (not too radical).
    Palnet fuel rails, Evo 8 I think 560cc Low imp. running about stock psi. Walbro 255 pump.
    Intercooled, running blow through MAF (tested with a PMAS (HPX Z32 spec) and with an actual Z32 MAF)


    I can easily get it up and running with quick resize, and MAF correction in nistune, then set the latency and have it idle proper etc. but I can take and set all 3 rows from 2200-2800 or so from 0-10 values up to 20, 30, 40 values, and not really have an effect on the issue, still have it dump lean every time. I have logged in the past, no real information of value, as there's no real hiccup or jump, other than the AFR dumping full lean.

    anyone else seen anything like this? I have my brothers and my car BOTH running great, with the same cams, bigger than stock injectors, Nistune, AND blow though setups. I dont understand why my friend's here is doing this!
    Damn dirty angels....these cars!

    Current Daily Driver - 86 Turbo.
    Under the cover - THE BANANA… that needs to be re-energized.
    sigpic
  • #2
    Read about a similar issue where the maf was the culprit. Try swapping maf?.
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #3
    Also I experienced similar symptoms on my own at about 3100 rpm. Maf tested way out of spec. Swapped it with one that was in spec and it's good.
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #4
    I have tried it with the Z32 Spec PMAS (which is currently working GREAT in MY car. his now has a working Z32/J30 MAF in it now, with same issue - that's why I swapped them out.

    No relation to my issue.
    Damn dirty angels....these cars!

    Current Daily Driver - 86 Turbo.
    Under the cover - THE BANANA… that needs to be re-energized.
    sigpic
  • #5
    seriously considering jumping to MS2 to get away from this issue…
    Damn dirty angels....these cars!

    Current Daily Driver - 86 Turbo.
    Under the cover - THE BANANA… that needs to be re-energized.
    sigpic
  • #6
    Originally posted by Axel kain
    seriously considering jumping to MS2 to get away from this issue…
    But didn't the issue still exist between different Nistune boards? Didn't you try it on a stock-ish tune and it didn't do it?
    Prius… because Pretentious wouldn't fit across the back of the car…

    Cheap, Fast, Reliable - pick any two

    My 1986 Turbo Build
  • #7
    Im going to take my 89 nistuned ecu to it and see what IT does next....
    Damn dirty angels....these cars!

    Current Daily Driver - 86 Turbo.
    Under the cover - THE BANANA… that needs to be re-energized.
    sigpic
  • #8
    swapped ECU's, tried a different coil just in case, swapped with new stock plugs and wires (plugs at .035 or so) so at this point im only thinking it's a sensor/ devise issue, as the ECU and basic ignition system has been ruled out. I tested spark at idle/free rev and compared to my non-issue car, noticing both are same. plus considering how well it runs WHEN IN boost. (above 2500)

    Im almost tempted to try to find new harness connectors and just make my own harness from the ECU pigtail… driving me nuts!
    Damn dirty angels....these cars!

    Current Daily Driver - 86 Turbo.
    Under the cover - THE BANANA… that needs to be re-energized.
    sigpic
  • #9
    My NA2T is having the same issue. Stock.
    Feedback- viewtopic.php?f=18&t=19840
  • #10
    Are you running 02 sensor.
    Cha iro

    enjoy building it yourself.
    if it fails, fuck it.
    at least you gave it a whirl.
  • #11
    So you ruled out the MAF?

    How about the CAS?

    Did you datalog the problem in Nistune?
    Shiro #443

  • #12
    running wideband, open loop. with the feedback deselected, and voltage out of range. regardless it would be ignored.

    I have swapped from the PMAS Z32 spec, to an actual Z32 maf now. same issue. PMAS is working perfectly in my car. CAS has a "07" unit. pretty sure I swapped it from a replaced "06" unit as problem solving. I have done a few datalogs. all show nothing other than the O2 dumping lean. TP, MAF, Ignition etc etc all are consistent.
    Damn dirty angels....these cars!

    Current Daily Driver - 86 Turbo.
    Under the cover - THE BANANA… that needs to be re-energized.
    sigpic
  • #13
    Yup that is a weird problem. I'm stumped. Is it just a reading on the O2 sensor that shows lean or can you feel it too?
    Shiro #443

  • #14
    Yeah, you definitely feel it. The tuner put it nicely: It runs like shit.
  • #15
    Yeah, it jumps lean and is like someone just threw timing in the ditch, as it just bogs and falls on it's face. if you have momentum enough to get past it, can run awesomely!
    Damn dirty angels....these cars!

    Current Daily Driver - 86 Turbo.
    Under the cover - THE BANANA… that needs to be re-energized.
    sigpic
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