ECU LED's blink while running?

  • #1

    ECU LED's blink while running?

    I searched the EF&EC section but could not locate a description of the function of the LED's on the ECU while the engine is running. I'm sure I just missed it, but I got lost in the flow charts and it was late…

    I've got a problem that the engine will idle but starts surging and then bogs as I give it accelerator input. I've noticed that as I first press the pedal, one of the lights on the ECU comes on, then as it begins to surge/bog the other light comes on as well. Can't remember which comes first. Haven't read the self-diagnostic codes yet, as I just got back working on it. I know how to do that, but wanted to see if this is useful in troubleshooting first.

    As always, I bow at the feet of the Z31 deities and with great supplication request their knowledge…
    '86 NA - original owner (1986-93) and final owner (2005-present)

    My build thread: http://z31performance.com/showthread…-Got-mine-back

  • #2
    Well, I didn't find the explanation of the LED's, but I did solve the bogging problem. It turns out the coil wire to the distributor was not very well seated on the coil end. It was good enough for the engine to crank and idle, but wouldn't support the additional required current to fire at elevated rpm's… the one time it worked properly, I must've accidentally bumped it and seated it better, then bumped it again next time I was in that area of the engine bay.

    Oh the ways the Z can frustrate us…
    '86 NA - original owner (1986-93) and final owner (2005-present)

    My build thread: http://z31performance.com/showthread…-Got-mine-back

  • #3
    I had the passenger kick panel off for a month or so and noticed something similar with the ECU. On line it would cycle a pattern between the green and red LEDs, but while going up a particularly steep hill with a bit more throttle, it would start flashig the red light. Sometimes while cruising it would flash both at the same time.

    I didn't look into it much, but I guessed it could vary from something like detecting a fault to flashing from something changing under various points of acceleration.
    '86 300ZXT GLL
    '78 Datsun 280Z BP
    '11 Saab 9-3 Aero XWD
  • #4
    Could it be the Mixture Ratio feedback system flashes? If its not on diagnostics mode I think it will display the red - green flashing from the ECU & exhaust gas sensor. Havent got the FSM infront of me, sorry.
    I Drink, therefore I am....
    84 50th AE, Australian Version (N/A, 2+2, Cloth interior, Digi Dash and Auto Climate control)
  • #5
    Green indicates rich, red is lean. Under load it should flash green. Then at idle I think you should see it flash back and forth, indicating proper o2 operation.
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #6
    Thanks… will observe next time I crank it up. If there's a place in the FSM that describes this feature, would like to have that for future reference.
    '86 NA - original owner (1986-93) and final owner (2005-present)

    My build thread: http://z31performance.com/showthread…-Got-mine-back

  • #7
    I did read it. But I don't remember where.
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #8
    It's in the EF section I think, under the mixture ratio feedback system.
    I Drink, therefore I am....
    84 50th AE, Australian Version (N/A, 2+2, Cloth interior, Digi Dash and Auto Climate control)