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  1. #1

    Injector size VS mod; what is my ECU thinking?

    Hello gents,

    Great forum; here goes with my first post..

    I have recently purchased a used 2008 speedster 150 215hp boat. As many others have posted here, I am on my way to the 100hr mark and the x-charger is looking appealing vs the SC rebuild; everything else will stay stock except maybe intake in the future. I see lots of talk about injectors; some say stock is good, some say we need 42's, also some debate on an aftermarket PR or even pump. This is were I need help, in making/understanding the proper choice.

    I probably need to be scooled here as I think I must be missing something: Am I right in my following logic??? Without reading this forum I would have guessed that my engine had a manifold absolute pressure sensor. If I upped the boost ( with x-charger), the ECU would adjust fuel (once in closed loop) with the known injector and rail pressure maintaining a proper AF. The only problem might be at WOT where by injector/pressure or fuel pump can't keep up. If I were to install 42's, the AF would be wrong across the board by default but the injector/pressure may reduce the effect of a lean condition at WOT.

    Does the bigger injector help deal with a lack of corrected timing at the higher boost levels or does the ECU correct timing for the measured boost and temperature as well?


  2. #2
    mac_man_luke's Avatar
    Join Date
    Sep 2010
    South Australia
    I believe the stock ECU is only programmed for about 3psi more boost than stock and the injectors run out of duty cycle (eg 100%)

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