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Procharged 7.4 mpi question

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  • Procharged 7.4 mpi question

    Hello again guys, im having an issue with my 7.4 mpi. Ive only had the boat for a few months and it runs very rich a idle and very lean at wot. I ve played with fuel pressure enough to get it to richen up at wot but of corse that doesnt help the idle mixture being so rich i get fuel and soot out the exhaust. I thought perhaps the injectors were clogged so it took the out and individually cleaned them up good but that hasnt helped. Im now wondering if the map sensor ( still in the manifold) should be relocated somewhere where boost isnt present like in the intake pipe. Vin L354355. Enging has been rebuild with high compression forged pistons.

  • #2
    Ayuh,..... Welcome Aboard,.... Was the 'puter reprogrammed to match the modifications to the motor,..??

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    • #3
      Im not sure to be honest like i said i ve only had it a few months and its always run like that. The plugs keep fowling and i have to be real carrful at wot because the egt s sky rocket and the motor actually knocks and then retards because of it unless i crank up the fuel pressure

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      • #4
        Someone put a procharger on it without having the ECM remapped, or it was remapped but was done incorrectly, in any case your looking at trouble.

        Remove the ECM and see if it has a sticker from Arizona or Whipple on it.
        What did you do to the fuel pressure?

        Edit: high compression with a procharger??
        Last edited by AllDodge; September 11th, 2019, 08:12 AM.
        94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
        95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
        07 Seadoo GTX
        Merc Adults Only VP Adults Only
        G-Dad always said "First Liar doesn't stand a chance"

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        • #5
          superchargers and blowers require a LOWER compression motor
          https://www.procharger.com/basic-engine-building-specs
          NO PERSONAL QUESTIONS, THIS IS WHAT THE FORUM IS FOR.

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          • #6
            it sounds like you are running out of fuel and possibly the ECM wasnt programmed for the whipple charger or the injectors are stock.

            something is not right

            I also agree, generally the compression is dropped for a blower.
            Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

            1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

            Past Boats
            1970 Wooster Hellion - Merc 9.8
            2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
            1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

            What’s behind you doesn’t matter.Enzo Ferrari

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            • #7
              Sry didnt meen high compression but higher than stock compression. The builder installed 454 mag forged pistons in it. Can the ecm be remapped without dyno testing ? I live around ottawa canada and there arent any marine dynos around.

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              • #8
                Blower needs lower then stock compression

                Can the ecm be remapped without dyno testing ?
                Dyno measures power you need to measure Air Flow Ratio (AFR) using O2 sensors.

                Your ECM can be remapped using MEFI Burn software with )2 sensors and a AFR meter, or can contact Whipple and have them reflash for your build if it can be done.
                94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                07 Seadoo GTX
                Merc Adults Only VP Adults Only
                G-Dad always said "First Liar doesn't stand a chance"

                Comment


                • #9
                  Sign up today
                  Thanks for the replies gentlemen ill contact procharger and see what they have for my application

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