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  1. #1

    question about injectors

    While i was reading super info on this site, i was curius about smt and i would appreciate any opinions. By going to 42lb injectors or bigger, would this make any different in the amount of fuel going into the engine, without an aftermarket ecu? What i mean is that ok, my motor has injectors capable for more fuel, but doesn't "someone" has to "tell" the system to let more fuel go into the engine?


  2. #2
    home of the dislexic fingers breon's Avatar
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    yes .....the only thing the ecu does is tell the injector to stay open x long...the bigger the hole (injector size)..or the more pressure behind it ....the more fuel it will add..across the entire rpm range..

  3. #3
    Quote Originally Posted by breon View Post
    yes .....the only thing the ecu does is tell the injector to stay open x long...the bigger the hole (injector size)..or the more pressure behind it ....the more fuel it will add..across the entire rpm range..
    So from what i can understand, larger injectors (42s or 50s for example) will not do anything by themselves unless you are going to combine them with an after market ECU, or am i missing something here...

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    Moderator Snoman's Avatar
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    Quote Originally Posted by sigma rxt View Post
    While i was reading super info on this site, i was curius about smt and i would appreciate any opinions. By going to 42lb injectors or bigger, would this make any different in the amount of fuel going into the engine, without an aftermarket ecu? What i mean is that ok, my motor has injectors capable for more fuel, but doesn't "someone" has to "tell" the system to let more fuel go into the engine?
    The bigger injectors are metered to let a certain amount of fuel flow through them..As Anthony stated,the ECU just tells the injectors how long to stay open...

    For example; 38 lbs injectors will flow 38 lbs of fuel in one hour,42s-42 lbs of fuel in one hour as 50s will flow 50 lbs of fuel in one hour....


    The ECU does not know if you have 38s,42s or 50s, it just tells the injectors what duration to open and close..

  5. #5
    Quote Originally Posted by Snoman View Post
    The bigger injectors are metered to let a certain amount of fuel flow through them..As Anthony stated,the ECU just tells the injectors how long to stay open...

    For example; 38 lbs injectors will flow 38 lbs of fuel in one hour,42s-42 lbs of fuel in one hour as 50s will flow 50 lbs of fuel in one hour....

    The ECU does not know if you have 38s,42s or 50s, it just tells the injectors what duration to open and close..
    Now it is clear to me. thanks for the info.And smt else the was brought up in my mind..Does the ECU also senses the temperature so as if needed it leave the injectors more time open in order to compensate the heat, or does every ECU is programmed for a specific time interval. For example the stock ECU works with certain time intervals in comparison with an after market ECU which is programmed for different time intervals( probably larger intervals where injectors are open). I am trying to figure out how the system works, my apologies if i am asking a lot of things..

  6. #6
    XDAILY's Avatar
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    So wait if you just added 42s or 50s wouldnt the engine just run rich, maybe flood?

  7. #7
    Eastside Powersports Slow 91's Avatar
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    yes. i have a 4tec here right now that the owner tried to save money and use some cheap no name brand car injectors which were ALOT more injector than he needed and it washed the cylinders out and ruined all his bearings.

  8. #8
    XDAILY's Avatar
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    Oh. Is there a How to on installing them?

  9. #9
    rmk82nd's Avatar
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    Not sure if these are in correct order but this is what I remember. Simple to do just remove dipstick, take off plastic cover, unscrew fuel rail, injectors pop out install new ones. Be sure to lay a towel down you will spill some fuel that the injectors hold in.

  10. #10
    MSRXP's Avatar
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    Quote Originally Posted by rmk82nd View Post
    Not sure if these are in correct order but this is what I remember. Simple to do just remove dipstick, take off plastic cover, unscrew fuel rail, injectors pop out install new ones. Be sure to lay a towel down you will spill some fuel that the injectors hold in.
    You have to remove the black clips that hold them in place. DO NOT DROP OR LOSE THEM. Do them one at a time to prevent issues.

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