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Thread: Cruise Control Surging

  1. #1
    Tuner in Training
    Join Date
    Feb 2013
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    41

    Cruise Control Surging

    Hope someone can please help me out?
    I've got an issue with my car that I've never been able to sort out - with cruise control surging especially going up or down hills. Flat road its not too bad.

    I can't find the parameter I need to change.
    It seems as though when its in cruise control as it slowly releases the throttle it goes in Spark Source mode "Closed throttle Decel" a bit too early (I think) and also the Throttle Angle Source is going into "Idle control mode"
    When this happens it feels like the throttle has been fully shut and then a split second later it picks up and goes again.
    Then it starts building boost; then it over shoots the target it then decels again. Looking at the speed though its ok within 1kmh.
    After examining the logs I can't see any particular trend that causes this.
    It's not related to a particular throttle position, map sensor value, engine load etc.
    When it decels I noticed that the cam angles change a heap and there's a huge amount of cam error.
    I have DFCO disabled.

    I've changed so many things on this ecu I can't figure out whats wrong. I'm a bit lost. Maybe HPtuners doesn't have the parameter I need to change.
    I would like to raise the reference point (whatever that is) at which it goes into closed decel spark source. Maybe if it stays in Base Spark source it won't do it.

    I'd also like to be able to change the rate at which is opens the throttle to accelerate in cruise mode. I can't find any settings for the ETC relating specifically to cruise mode. I've tried changing the Feedback Control proportion under ETC menu but it doesn't make much difference. Its always too abrupt it needs to be smoother.

    Heres a screenshot.
    cruise.jpg

    My car is a XH Ute with BF NA ecu [HACCKA2] with turbo logic enabled. Using OSS and I've changed rear tyre size but the speedo is ok within 1-2kms.
    Any help would be appreciated.
    Last edited by luke111; 1 Week Ago at 05:10 AM.

  2. #2
    Advanced Tuner
    Join Date
    Apr 2014
    Posts
    354
    ive asked support a cpl times for some cruise tables, i think they werent super keen on adding any missing cruise tables or didnt know where they are. so would be good to get some useful info with which tables are doing what for it.
    had you found any other tables or settings that were cruise related?

  3. #3
    Tuner in Training
    Join Date
    Feb 2013
    Posts
    41
    I made some progress over the past couple of days by adjusting the Proportional Gain - Electronic Throttle; Feedback control.
    I setup some datalog traces for ETC Desired vs ETC Actual and noticed some lag and oscillation. I ended up setting the gain to 0.9 and its a lot better. Great everywhere on cruise now except on the steeper hills where it makes too much boost too quickly and the cruise system can't react fast enough so it cancels.

    Whenever I added gain to the Integral or Derivative gain it just made things worse.
    Sadly though, I always have some ETC error whenever MAP pressure goes above 100kpa. The more boost, the higher the error.
    I made another user maths parameter with ETC Desired- ETC Actual to see the offset and the ETC error pid coming out of the ecu is different again.
    I have come to the conclusion that an NA ecu won't work properly with boost. In the factory service manual it says that the turbo ecu uses the boost pressure in the pipe before the throttle body for reference on cruise.

    Just in case anyone else is interested; I came across this excellent video from Motec on how PIDs work.
    I needed to get an understanding of what P.I.D gains do before I made any changes.
    PID Parameters Explained - MOTEC
    Last edited by luke111; 3 Days Ago at 04:34 AM.

  4. #4
    Tuner in Training
    Join Date
    Feb 2013
    Posts
    41
    Heres a screenshot of what it looks like on cruise control on a flat road. The ecu is doing this opening/closing of the throttle all by itself. This was set on Prop Gain 0.1 (Standard settings)
    Attachment 87882


    This is yesterday cruising down the motorway locked on 100km/h. Its nice until I come to a hill then the throttle starts surging. It doesn't seem to recover ok usually but its still annoying. This log is with Proportional Gain set to 0.9
    I found that to be the best. 0.8 still had just a touch of lag and 1.0 seemed to overshoot the desired by 0.5-1 deg most of the time.
    The ETC Desired vs ETC Actual traces now pretty much overlap each other perfectly.

    I also noticed now that when the A/C cuts in and our the idle doesn't fluctuate as much as it used to. Same as when I change from Park - in gear it so much smoother than before.
    Attachment 87883