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HELP: Bad idle speed fluctuations.....car almost dies...???

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  • HELP: Bad idle speed fluctuations.....car almost dies...???

    May battery died, and I put a new one in the other day. Ever since then my idle speed has been fluctuating badly. It idles fine in and out of gear when at a rest. The problem occurs when the car is moving at a crawl. For example, when coming to a stop at a stop light, the engine speed surges significantly. It sounds like it may die at the low end, and at the high end of the fluctuation, its enough where I have to step on the brake harder to keep from rear ending the person ahead of me. Once in a while it will actually die when backing up after the car has just been started.

    I have already done the idle relearn procedure described on 60v6.com, but it made no difference. What happened to my car when I changed the battery? Any input is appreciated!!
    \'90 Cutlass Supreme SL coupe - 3.1L LH0 V6/HM 4T60 -- every factory option
    Flowmaster 40 - no cat // K&N FilterCharger // KYB GR-2\'s // Stant 180º SuperStat

  • #2
    Its the idle relearn.

    Did you do it with a programmer? If not it makes it un certian wether or not it has been done correctly.
    1993 EXT. CAB, 3.4L V6 TBI, 5spd manual. Sonoma
    1990 4Door, 3.2L V6 TBI, 5spd manual. 4X4. Trooper
    Because... I am, CANADIAN

    Comment


    • #3
      I followed the relearn procedure described on this site.

      The thing is though, it generally idles fine out of gear, and most of the time when its in gear. The problem occurs while coming to a stop. Around 1-8MPH is when the revs fluctuate badly.

      Could this be a IAC problem?
      \'90 Cutlass Supreme SL coupe - 3.1L LH0 V6/HM 4T60 -- every factory option
      Flowmaster 40 - no cat // K&N FilterCharger // KYB GR-2\'s // Stant 180º SuperStat

      Comment


      • #4
        Yes it could be the IAC but why justa after changing the battery.

        That relearn is not correct.

        1. Set parking brake, start engine in P or N position. Warm-up vehicle to normal operating temperature.
        2. Allow vehicle to idle for one minute in N, Select D and allow to idle for one more minute.
        3. Accelerate at normal throttle position, 20-50% untile vehicle shifts into top gear.
        4. Cruise at light to medium throttle
        5. Decelerate to a stop, allowing the vehicle to downshift, and use brakes normally.

        Try that
        1993 EXT. CAB, 3.4L V6 TBI, 5spd manual. Sonoma
        1990 4Door, 3.2L V6 TBI, 5spd manual. 4X4. Trooper
        Because... I am, CANADIAN

        Comment


        • #5
          just out of curiosity, you did pull the ECM fuse that's underhood, next to the fuel pump relay/aux positive terminal, yes?
          Brian

          '95 Cutlass Supreme- "The Rig"
          3400 SFI V6, 4T60e
          Comp Cam grind, LS6 valve springs, OBD2 swap, Tuned
          2.5" DP/ 2.5" dual exh/ Magnaflow Cat/ crap mufflers/ 3500 Intake manifold/ 65mm TB
          TGP steering Rack/ 34mm Sway Bar/Vert STB/ KYB GR2's

          '08 Chevy Trailblazer SWB 1LT "Smart Package"- LH6 5.3L V8/4L60e, A4WD

          Comment


          • #6
            Thanks for the procedure, betterthanyou.

            Brian, no I did not. I didn't realize the ECM has TWO fuses, lol. I'll pull the one by the fuel pump relay and try it again.
            \'90 Cutlass Supreme SL coupe - 3.1L LH0 V6/HM 4T60 -- every factory option
            Flowmaster 40 - no cat // K&N FilterCharger // KYB GR-2\'s // Stant 180º SuperStat

            Comment


            • #7
              UPDATE: I cleaned the IAC and relearned the idle, and the car STILL has the same problem.

              Is it safe to say I need to replace my IAC?
              \'90 Cutlass Supreme SL coupe - 3.1L LH0 V6/HM 4T60 -- every factory option
              Flowmaster 40 - no cat // K&N FilterCharger // KYB GR-2\'s // Stant 180º SuperStat

              Comment


              • #8
                UPDATE #2: I've realized that it only stalls when in gear. I'll come to a stop and the idle speed will be going up and down and eventually die. However, if I pop it in Neutral, it will run like normal.

                Why would the idle fluctuate and eventually die in Drive only? Torque converter issue, or IAC?
                \'90 Cutlass Supreme SL coupe - 3.1L LH0 V6/HM 4T60 -- every factory option
                Flowmaster 40 - no cat // K&N FilterCharger // KYB GR-2\'s // Stant 180º SuperStat

                Comment


                • #9
                  vacuum issue or idle learn issue.
                  Brian

                  '95 Cutlass Supreme- "The Rig"
                  3400 SFI V6, 4T60e
                  Comp Cam grind, LS6 valve springs, OBD2 swap, Tuned
                  2.5" DP/ 2.5" dual exh/ Magnaflow Cat/ crap mufflers/ 3500 Intake manifold/ 65mm TB
                  TGP steering Rack/ 34mm Sway Bar/Vert STB/ KYB GR2's

                  '08 Chevy Trailblazer SWB 1LT "Smart Package"- LH6 5.3L V8/4L60e, A4WD

                  Comment

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