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My Launch control Bog keeps getting worst

Discussion in 'BMW DCT - GS7D36SG' started by ganque, Jun 11, 2018.

  1. ganque

    ganque Lurker

    Messages:
    19
    Ride:
    BMW 135i N55 DCT pure stage 2
    Hey everyone,
    So as everyone knows the stock Launch Control on DCT cars get useless as soon as you start adding more power to it. And of course once you go to an upgraded turbo is just a shitty functionality.
    However I've been noticing that my LC is getting worse everytime I use it. I've noticed that it's taking longer periods of time (milliseconds) to recover from the DSC intervention.
    Is this a normal thing?

    I tried to lower boost all on 1st gear to 8 psi, then lower to 5 psi and even at almost no boost at all but the car still does this... so it's not boost or power related at all. Maybe a transmission setting issue?
    I've already tried to reset adaptations via INPA, Tool32 and MHD but nothing... the car still does this everytime. I've tested this on regular tires and drag radials... same deal.
    Maybe clutches are about to die? Differential? I really don't know what to look at exactly. Maybe my DSC module is F'd up?


     
  2. aus335iguy

    aus335iguy Lieutenant

    Messages:
    610
    Ride:
    335i DCT 2009
    Do you have a log ?
     
  3. ganque

    ganque Lurker

    Messages:
    19
    Ride:
    BMW 135i N55 DCT pure stage 2
    Sure.
    This was on regular boost targets set to 13 psi at 1st gear, 15 psi at 2nd gear and the rest at full boost.
    A boost leak was found next day so ignore the fact that boost was not hitting targets.
     

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  4. ganque

    ganque Lurker

    Messages:
    19
    Ride:
    BMW 135i N55 DCT pure stage 2

    Attached Files:

  5. aus335iguy

    aus335iguy Lieutenant

    Messages:
    610
    Ride:
    335i DCT 2009
    The throttle is held at 3500rpm until you let off the brakes. That’s why torque and throttle are a straight line in your screen shot. The launch occurs in the timeline where you see RPMs start to drop.
    At that point youre 100% throttle. In fact once your throttle opens its pegged at 100% the whole time through the log. I dont see a throttle closure once the clutches drop.

    The torque seems to be introduced in steps though and that’s whats giving you the feeling of hesitation I imagine.
     
  6. ganque

    ganque Lurker

    Messages:
    19
    Ride:
    BMW 135i N55 DCT pure stage 2
    Yeah it does feel like the car hesitates for an entire second, it just stays rolling at low speed for that time period then it starts... but that second is enough for ANY car to jump away from me... which is my struggle.
    How can I address this? Should this be something that can be fixed by a custom tune? Or is it something mechanical related like clutches or diff?
     
  7. aus335iguy

    aus335iguy Lieutenant

    Messages:
    610
    Ride:
    335i DCT 2009
    It’ll never launch like an AWD Audi that’s for sure and I’m not sure if that’s your expectation. It should in theory get off the mark smartly with standard boost levels in 1st gear. When stock it spins all through first gear in my car. Best thing I can suggest is to talk to your tuner and consider the M3 TCU conversion. No DSC on that...
     
  8. jyamona

    jyamona Sergeant Vendor

    Messages:
    433
    Location:
    Philly
    This is 100% not needed, as the DSC requirement can be avoided via a DME software hack. It works on N54 as seen by the vid Terry C took of my code change. I do not have time to work it out for N55 currently, but the process will be the same.

    OP, I received your PM but have not had time to do the work for N55.
     
  9. Twisted Tuning

    Twisted Tuning Lieutenant Vendor

    Messages:
    667
    Theres no reason to do an M3 conversion like Jake said. There are tables for everything on the N55. From how much torque the car makes at launch, the delay before releasing and actually launching the car, to how long the DSC/TC inhibits the car and how much. I've been playing with N55 DCT launch control for weeks now deciding whats needed and whats not.

    This is just my opinion, No DSC/TC at all is actually not the answer (albeit it can be disabled via one of the tables) .... mainly because once you do launch under actual power. You have no clutch to slip like a manual so the DSC actually helps modulate the take-off. One of the BEST launch control systems on the market (ProEFI) uses traction control-like algorithm at launch.

    But yea, you can pedal the car of course. Just give me some time, lots of things coming for N55
     
  10. aus335iguy

    aus335iguy Lieutenant

    Messages:
    610
    Ride:
    335i DCT 2009
    Gents, I appreciate the work that needs to go into making LC work the way we want it to. Im N54 and id love to have it. Id pay to have it. I think @ganque would too.
     
  11. jyamona

    jyamona Sergeant Vendor

    Messages:
    433
    Location:
    Philly
  12. ganque

    ganque Lurker

    Messages:
    19
    Ride:
    BMW 135i N55 DCT pure stage 2
    Yeah I'm really down to get LC work via MHD flash. I have a drag race event (money is involved), if anyone here is able to help me out with the launch please let me know. I know it won't launch like an AWD, but I want at least to get the proper power down to the floor when releasing the brake pedal.
     
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