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Normal 350 MAG MPI Idle speed-- 600?-gctid814484

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    Normal 350 MAG MPI Idle speed-- 600?-gctid814484

    Factory manual indicates idle should be @ 600 rpm, but my new-to-me 2004 288 with 350 Mag MPI idle varies between 800 - 1200 rpm, so I am changing the IAC valve.

    Should I really expect 600 rpm after the IAC replacement? (If so, this will really help docking maneuvers!)

    #2
    "mtcaprio" post=814484 wrote:
    Factory manual indicates idle should be @ 600 rpm, but my new-to-me 2004 288 with 350 Mag MPI idle varies between 800 - 1200 rpm, so I am changing the IAC valve.

    Should I really expect 600 rpm after the IAC replacement? (If so, this will really help docking maneuvers!)
    Can't tell you if it's the AIC or not but yes you should expect around 600 RPM at idle.
    Dave
    Edmonds, WA
    "THE FIX"
    '93 2556
    Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

    The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
    Misc. projects thread
    https://www.baylinerownersclub.org/f...56-gctid789773

    Comment


      #3
      Before you spend a bunch of $$$ and time on an IAC valve you might verify the throttle cable and linkage throw is seating fully closed.
      Jim Gandee
      1989 3888
      Hino 175's
      Fire Escape
      [email protected]
      Alamitos Bay, SoCal

      Comment


        #4
        +1 What Jim said...

        Disconnect the throttle cable and see if the idle will decrease. Alot of times it can be just a sticky throttle cable, not fully retracting,
        Joon, Kathy, Jaden & Tristan
        Uniflite 42 AC, DD 671N
        93 3058 sold
        92 2855 (day boat)
        91 Fourwinns 205 (lake boat)
        Longbranch WA
        Life is Good

        Comment


          #5
          On a warm engine, should idle 600-650.
          Be good, be happy, for tomorrow is promised to no man !

          1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

          '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

          Manalapan N.J

          Comment


            #6
            "mtcaprio" post=814484 wrote:
            Factory manual indicates idle should be @ 600 rpm, but my new-to-me 2004 288 with 350 Mag MPI idle varies between 800 - 1200 rpm, so I am changing the IAC valve.

            Should I really expect 600 rpm after the IAC replacement? (If so, this will really help docking maneuvers!)
            [color]blue wrote:
            Yes, it will!

            If the Marine Engine was equipped with a standard auto type transmission with a manually operated clutch, the RPM would not be as critical.

            However, our stern drive Marine Engines are equipped with either a Dog Clutch or Cone Clutch system.

            Intrinsically, the Dog Clutch or Cone Clutch wants to remain Engaged while torque is against the propeller.

            The Higher RPM, the more torque against the clutch..... the lower RPM, the less torque against the clutch.

            With a recommended low idle RPM, it becomes much easier to disengage the Dog or Cone clutch system.[/color]
            Rick E. Gresham, Oregon
            2850 Bounty Sedan Flybridge model
            Twin 280 HP 5.7's w/ Closed Cooling
            Volvo Penta DuoProp Drives
            Kohler 4 CZ Gen Set

            Comment


              #7
              "mtcaprio" post=814484 wrote:
              Factory manual indicates idle should be @ 600 rpm, but my new-to-me 2004 288 with 350 Mag MPI idle varies between 800 - 1200 rpm, so I am changing the IAC valve.
              I don't recall exactly what RPM mine idles at, but 600 RPM sounds about right. It is definitely not as high as 800-1200 RPM.. There's a significant amount of throttle movement between idle and 1000 RPM. If I remember right, at 1000 RPM I'm just about at or above the harbor's 5 MPH speed limit.
              1994 2556, 350 MAG MPI Horizon, Bravo 2

              Comment


                #8
                It was the throttle cable adjustment that was causing the high idle. Thanks for the tips.

                Comment


                  #9
                  Originally posted by mtcaprio View Post
                  It was the throttle cable adjustment that was causing the high idle. Thanks for the tips.
                  Thanks for the update, glad it turned out to be a simple fix
                  Dave
                  Edmonds, WA
                  "THE FIX"
                  '93 2556
                  Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                  The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                  Misc. projects thread
                  https://www.baylinerownersclub.org/f...56-gctid789773

                  Comment

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