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Thread: Pushing on brakes at idle - small cam - Can Brake Torque Limit help?

  1. #1
    Potential Tuner
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    May 2019
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    Pushing on brakes at idle - small cam - Can Brake Torque Limit help?

    Hi all,

    Ive got a 6.0 / 6l80e combo with E38 /T43 ecms.

    Its in a landrover so just has a small cam - VCM532 - 215/223 @112.

    I got it back from the tuner and it was idling at around 780rpm. But it was pushing quite hard on the brakes at the lights etc.

    Ive dropped the idle to 630 and the MAP is 61kpa in Drive, and smoothed out the timing chop, this helped a lot, but it still pushes.
    Granted the landrover brakes are not great, and perhaps need more vacuum, but they are 4 wheel disc, so I'm keen to try and find a solution before trying an external vac pump setup

    I found a setting "Brake Torque Limit", where you set the max torque for a certain KPA and Throttle range. I set the idle areas to very low torque number, but it doesn't seem to do anything.

    If setup correctly, how could I tell if this is being activated on the scanner?

    Also, if anyone has any other suggestions, I'd be very appreciated.

    Thanks.

  2. #2
    Advanced Tuner mbray01's Avatar
    Join Date
    Dec 2013
    Location
    Pearl River, La.
    Posts
    792
    BRAKE TORQUE LIMIT IS TORQUE MANAGEMENT. (HOW MUCH TORQUE MANAGEMENT IS USED WHILE BRAKES ARE APPLIED, AND THROTTLE APPLIED)(POWER BRAKING). IT WILL NOT DO ANYTHING FOR WHAT YOU ARE DESCRIBING. TO CORRECT THE ISSUE YOU HAVE YOU NEED TO CREATE MORE VACUUM, THE EASIEST WAY WOULD BE TO ADD IDLE TIMING, MORE TIMING, MEANS LESS THROTTLE BLADE OPENING TO ACHIEVE THE SAME RPM. I WOULD IDLE IT HIGHER AS WELL, I WOULD LIKELY BE AROUND 700 RPMS, WHICH WILL HELP WITH VACUUM AS WELL. iDLE RPM YOU WILL HAVE TO TOY WITH, YOU WANT THE MOST RPM YOU CAN ACHIEVE, WITHOUT IT PUSHING THROUGH THE CONVERTER
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    15yr Master Tech.
    Custom Car Fabrication, Customization, High Performance.
    GM World Class Technician
    Shop Owner

  3. #3
    Potential Tuner
    Join Date
    May 2019
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    Quote Originally Posted by mbray01 View Post
    BRAKE TORQUE LIMIT IS TORQUE MANAGEMENT. (HOW MUCH TORQUE MANAGEMENT IS USED WHILE BRAKES ARE APPLIED, AND THROTTLE APPLIED)(POWER BRAKING). IT WILL NOT DO ANYTHING FOR WHAT YOU ARE DESCRIBING. TO CORRECT THE ISSUE YOU HAVE YOU NEED TO CREATE MORE VACUUM, THE EASIEST WAY WOULD BE TO ADD IDLE TIMING, MORE TIMING, MEANS LESS THROTTLE BLADE OPENING TO ACHIEVE THE SAME RPM. I WOULD IDLE IT HIGHER AS WELL, I WOULD LIKELY BE AROUND 700 RPMS, WHICH WILL HELP WITH VACUUM AS WELL. iDLE RPM YOU WILL HAVE TO TOY WITH, YOU WANT THE MOST RPM YOU CAN ACHIEVE, WITHOUT IT PUSHING THROUGH THE CONVERTER
    Thanks Mbray!

    I'll give that a try.

    Cheers.