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Thread: Engine Won't Go Above 2K RPM!

  1. #1
    Join Date
    Jun 2020
    Location
    Columbus, OH
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    7

    Default Engine Won't Go Above 2K RPM!

    Hey Everyone! I'm using a LM7 from a 2003 Chevy 1500 topped with an LSA blower. Crank is 24x with a 1x cam. The 5.3L is backed with a 4L80E and all of it is being controlled by the Terminator X Max. I'm running stock LSA injectors that FIC has reworked to 1000 CCs (put into the tune as FIC1000). The truck is also DBW using ACDelco 12629992 (LSA) throttle body and 10379038 ACDelco pedal.

    The truck starts up fine and idles fine, but won't go above 2K RPM, nor over 10% throttle position no matter what the actual pedal position is. It's almost like it has some sort of limiter in place. I looked into the DBW safeties, but I can't figure out what the issue is.

    I've attached the datalog and tune files for more info.
    Attached Files Attached Files
    Last edited by dominic; 07-28-2020 at 12:16 PM.

  2. #2
    Join Date
    May 2014
    Location
    Bostwick, GA
    Posts
    231

    Default

    Brake pedal wired? AIRC, J3 B24 should have a +12V Input from the brake pedal.
    Injector Inspector
    USAF 1960-1964
    Drag racing since 1955

  3. #3
    Join Date
    Jun 2020
    Location
    Columbus, OH
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    Default

    I have it wired to the brake pedal on the side of the switch that's hot when the brake pedal is pressed. It shouldn't be on the constant +12V side, correct?

  4. #4
    Join Date
    May 2014
    Location
    Bostwick, GA
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    13.4 System Safeties
    Holley designed the Drive-By-Wire system to utilize a brake pedal switch input. This is wired to a +12V input from the brake pedal switch. If the brake pedal is depressed enough to activate the brake light switch, the following occurs:
     The ECU will not allow a throttle position over 10%, no matter how far the pedal is pushed. This consequently limits the opening of the throttle body.
    Before a pedal value over 10% will be recognized, the following must occur in this order:
     Brake pedal switch must be released
     Pedal position must go below 10%
     Fuel flow is limited to 30 lb./hr. as an additional safety.
    IMPORTANT! INSTALLATION OF THIS SAFETY CIRCUIT IS REQUIRED WHEN USING THE DRIVE-BY-WIRE FEATURE!
    DEFEATING OR NEGLECTING TO INSTALL THIS INPUT IS DONE SO AT THE USERS OWN RISK. THE USER
    ASSUMES ANY AND ALL LIABILITY FOR ANY DAMAGE, AS A RESULT OF A DRIVE-BY-WIRE MALFUNCTION.
    Injector Inspector
    USAF 1960-1964
    Drag racing since 1955

  5. #5
    Join Date
    May 2014
    Location
    Bostwick, GA
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    Default

    Quote Originally Posted by dominic View Post
    I have it wired to the brake pedal on the side of the switch that's hot when the brake pedal is pressed. It shouldn't be on the constant +12V side, correct?
    You have it wired backwards.
    Injector Inspector
    USAF 1960-1964
    Drag racing since 1955

  6. #6
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
    1,821

    Default

    Quote Originally Posted by dominic View Post
    I have it wired to the brake pedal on the side of the switch that's hot when the brake pedal is pressed. It shouldn't be on the constant +12V side, correct?
    This seems to contradict itself. You say you're on the hot side WHEN PRESSED. Which I read as not the constant +12V battery feed to the switch.
    So do you see permanent +12V or switched +12V (brake pedal depressed)?
    If you do have unswitched permanent +12V on the brake wire, that's why the engine won't rev up.
    The wire MUST BE connected to SWITCHED +12V from the brake switch. Gary
    Regards, Gary

  7. #7
    Join Date
    May 2014
    Location
    Bostwick, GA
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    Default

    Gary, I wonder if we'll find out?
    Injector Inspector
    USAF 1960-1964
    Drag racing since 1955

  8. #8
    Join Date
    Jan 2010
    Location
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    Default

    Quote Originally Posted by Chuck L. View Post
    Gary, I wonder if we'll find out?
    Waiting on Dominic. He might find his issue, when he understands what we've mentioned above. Gary
    Regards, Gary

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