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Thread: Error code 1518 and 1516 under higher boost applications with DBW

  1. #1
    Tuner in Training
    Join Date
    Apr 2012
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    14

    Error code 1518 and 1516 under higher boost applications with DBW

    I've been trying to sort out an issue for months now and have exhausted my experience along with what I've found searching on the problem. I have a 2004 LQ4 DBW setup on boost and E85. Stock intake and throttle body. It runs flawlessly until about 13lbs at which point it throws a 1518 and 1516. I can't determine if this is a byproduct of the throttle shutting off via some setting I've overlooked and then the boost holding the throttle blade open causes the error code. I can run all day long at 12-13lbs. When it starts to get above this range it throws these codes and enters reduced power mode.

    I'm open to any suggestions at this point as I feel my only next option is scrapping the ECM and throttle body or work towards an aftermarket EFI. I'm hoping someone smarter than I am can locate something I've missed in my configuration that is causing a forced throttle close condition under higher boost. I've swapped throttle bodies and installed an LS3 TB with an xlink and same issue. It's strange that it only occurs at higher boost levels.

    Specs:
    Stock LQ4 with a cam
    Stock Truck Intake/100lb injectors/3bar map conversion
    Truck DBW TB/LS3 TB with Xlink now
    Twin Precision 67/65 Turbos
    Stock ECM and modified stock wiring harness

    I tested all connections/wiring etc. I also assume that if it were wiring it wouldn't care about the boost level so much and occur all the time.

    Like I said I'm hoping I missed something in the torque management or otherwise because I can't make sense of why it would only cause the issue at around 14lbs of boost and up. Ive included a log file of the last run with boost cranked up a bit. When you see the throttle drop it is not me letting off. It shut down, then I got back into it and then it threw a code and shut down into reduced power mode.


    Any help would be greatly appreciated as I have already spent months trying to narrow this down. Thank you.
    Attached Files Attached Files

  2. #2
    Tuner in Training
    Join Date
    Apr 2012
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    14
    Still having issues with this and not sure where to go next with this. Anyone have experience with this issue and/or know a way around it? Any help would be appreciated as I'm out of ideas here. Thanks.

  3. #3
    Advanced Tuner
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    Jun 2007
    Location
    Finland, Europe
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    548
    ETC pedal position: how it is determined? Is there a physical sensor and if so, is it adjustable?

  4. #4
    Tuner
    Join Date
    Sep 2013
    Location
    SF Bay Area , California
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    159
    I read that high boost can sometimes keep the TB blade from opening properly on some throttle bodies that aren't rated for that much pressure. And then I think you get ETC desired too far off from ETC % , If the difference is beyond a certain range than you get REP and TPS/TAC codes. I noticed that you're at TPS %99 when your pedal% is at 78. That seems a little weird to me , I'm at pedal 110% when I'm at TPS 100%. I had a bad TB harness once and it threw p1515 and p1516 a lot. It looks like your logging too many things at once , it's probably taking away from the resolution of your logs. It will be easier to see what's going on if your logging bytes are below 24.
    2001 Z06 : 856/830 : Built LQ9 403ci : D1SC 17psi : Self-built , self-tuned.

  5. #5
    Tuner in Training
    Join Date
    Apr 2012
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    14
    Thank you for the replies. I definitely added a lot to try and catch everything going on in logging as I started to suspect an issue with voltage. I suspect that under higher boost levels it's causing a flutter in the throttle blade personally then tripping the error code. It only does it under higher boost levels. I figured if it were related to something in the tune or the harness it would do it at all boost levels but I can run up to about 10lbs and it never throws the code. I have a few extra parts gathered including an ECM on the way with the correct drivers for the IAC so I think I'm just going to swap out to DBC and be done with it at this point. Unfortuantely from what I've found there's no way to tune around or disable the 1518/1516 and I trying an LS7 throttle body didn't help.

  6. #6
    Tuner in Training
    Join Date
    Dec 2012
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    27
    Not sure if it would help, but I thought you had to run a silver blade throttle body, early ls7 or ls2
    I believe the ls3 and later ls7 have a gold blade and the blade moves backwards compared to the silver blade. From what I read when I was compiling parts for my build, the truck tb including the tbss have weak springs causing the flutter and float at higher boost.
    I have a truck intake with a ls2 tb and x link on a boosted 6.0, only minor run time, but no issues yet.

  7. #7
    Potential Tuner
    Join Date
    May 2018
    Posts
    1
    Op, ever figure out your issue?