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      01-03-2020, 12:02 AM   #23
TideMD
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Originally Posted by NoMoreAudi View Post
LoL at some people thinking it works all the time. News flash, it doesn't!
I don't think; I know without a doubt that - when properly initiated (i.e. - appropriate op temp, proper steps to activate LC, adequate time/mileage between LC attempts, etc.) - LC has never failed me to date.

Not entirely sure what's so "LoL" about that.
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      01-03-2020, 04:35 PM   #24
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Quote:
Originally Posted by TideMD View Post
I don't think; I know without a doubt that - when properly initiated (i.e. - appropriate op temp, proper steps to activate LC, adequate time/mileage between LC attempts, etc.) - LC has never failed me to date.

Not entirely sure what's so "LoL" about that.
Time has nothing to do with launch control attempt. If the transmission is overheated, you will get an error when trying to activate the feature and it won't even launch. After the transmission (maybe the clutch packs) cools down enough, launching can be resumed. Turning the car off and back on doesn't reset the sensor btw. It's safe to say that I've done more launches than most people so I know the functionality of it. I would guess about 100 launches while completely stock (including OEM tires, wheels, etc.) and about 200 launches after varying levels of modifications and 5 different sets of tires - sport cup 2s, pilot 4s, super sport, toyo R888R and ventus v12). My v12 set lasted about 1200 miles/ 1 month on the rears.

I'm referring to when it is "properly" being activated (it actually works when the car is cold, oddly enough) and the checkered flags come up... but the wheels spin like I'm on black ice. Perhaps a sensor was off or broken, which would explain for the car behaving the way it did. There seems to be 3 different ways I've experienced launch control; it gets activated and launches properly; it gets activated and smokes the tires completely or it doesn't activate at all (this only happened after doing about 6 launches back to back).
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      01-05-2020, 03:27 AM   #25
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I would agree with the above. LC works for me fine but you can’t do back to back for obvious reasons and I like this Fail safe. I was thinking it was thermal related or by a minimum number of miles driven before ready for launch.

What’s with the delay though? When you let good brake it doesn’t go right away there is a slight pause that’s feels like an eternity! No bueno!
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      01-06-2020, 12:47 PM   #26
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OP, I think the flash you have may have screwed with the setting. Anyways, the car performs better from a roll. haha
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      03-05-2020, 10:30 PM   #27
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Quote:
Originally Posted by papasmurf_m3 View Post
I would agree with the above. LC works for me fine but you can’t do back to back for obvious reasons and I like this Fail safe. I was thinking it was thermal related or by a minimum number of miles driven before ready for launch.

What’s with the delay though? When you let good brake it doesn’t go right away there is a slight pause that’s feels like an eternity! No bueno!
No, after I let off brake it disengages launch and no matter what falls to idle then moves but it doesn’t launch it just goes back to regular driving style
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      04-04-2020, 04:09 PM   #28
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Ok so I am the 2nd owner of this car bought it at 38k miles and it’s at 59k miles. Been to 4 different bmw dealers so far. Not one has told me these cars are due for a rear diff flush around the 40’s. So at 57k miles I changed the rear diff fluid and the launch control works now. Does this make since? I couldn’t imagine the system being that touchy with fluid. It works every time now. Doesn’t make much since in my book.
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      04-04-2020, 05:33 PM   #29
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it wouldn’t allow LC until the diff fluid was serviced. Maybe there is some confirmation done ✅ after that service that tells the computer LC is ok to use.
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      04-04-2020, 08:21 PM   #30
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I might be wrong, but I think you got to get the car hot....so drive it hard then, stop and launch it.
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      04-05-2020, 08:53 PM   #31
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Quote:
Originally Posted by papasmurf_m3 View Post
it wouldn’t allow LC until the diff fluid was serviced. Maybe there is some confirmation done ✅ after that service that tells the computer LC is ok to use.
I did the service myself so I have no idea. Due to old fluid.. When I drained it, it was black. It was so thin compared to the new fluid. Just touching the old fluid felt like water and didn’t feel slippery like when I put the new fluid on my hand it felt really thick and slippery if that makes any since. What I believe is happening is the module would deactivate due to sensing slip in the system because of the water like fluid, which would also damage the diff. Then when the new fluid was put in, it didn’t sense slip because it was thick enough and won’t cause damage. But I cannot believe it is that touchy. I mean it works every time now, It feels great. This seems to be a bit of a problem on these cars from who I’ve asked. So hopefully that should solve the problem, I also found out it looks like on the earlier car 2015-2017 they came with the wrong fluid and also the dealers are changing them still with the wrong fluid. I would advise to do it yourself. It’s very easy takes 30 min or so with a lift. The correct diff fluid for these cars is SAE 75w-140.
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      04-09-2020, 09:59 AM   #32
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Only one way to launch it: warm it then Gearbox S3, Engine sport+, press traction button until MDM disapear, brake with left, with right fully gas, take foot from brake and let car to change gears, even if car is on s3(manually) it will change automatically(launch control feature), don t try to take the foot from gas because launch will stop.
And the most important after a launch don;t try it anymore minimum 30 minutes. It will pop up errors at gearbox about temperatures.
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      04-11-2020, 05:25 PM   #33
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Quote:
Originally Posted by andrei.m4 View Post
Only one way to launch it: warm it then Gearbox S3, Engine sport+, press traction button until MDM disapear, brake with left, with right fully gas, take foot from brake and let car to change gears, even if car is on s3(manually) it will change automatically(launch control feature), don t try to take the foot from gas because launch will stop.
And the most important after a launch don;t try it anymore minimum 30 minutes. It will pop up errors at gearbox about temperatures.
Yes I know how to use it lol. Answer to this problem was diff oil needs to be changed to the right oil, so I highly recommend it. Also make sure you have good tires before you do it.
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      04-11-2020, 05:26 PM   #34
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I’ve also heard that if that doesn’t work the last resort would be to get a new diff module. But diff oil fixed mine.
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      04-12-2020, 09:22 PM   #35
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Quote:
Originally Posted by andrei.m4 View Post
Only one way to launch it: warm it then Gearbox S3, Engine sport+, press traction button until MDM disapear, brake with left, with right fully gas, take foot from brake and let car to change gears, even if car is on s3(manually) it will change automatically(launch control feature), don t try to take the foot from gas because launch will stop.
And the most important after a launch don;t try it anymore minimum 30 minutes. It will pop up errors at gearbox about temperatures.
One question I have is, for launch control are you forced to redline the first gear? Because on non launch control launches I tend to short shift 1st since my tires usually spin towards the upper rev range
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      10-15-2021, 04:08 PM   #36
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So what’s the solution , I was just at the track with my m4 first 2 passes everything worked good, after 20 minutes I did a third pass on this pass I set the to 3k and then I let off the brake and held the gas pedal down the rpms dropped to 1k and power was immediately gone after.
I did 2 more passes after this and same outcome . I left the track and did launch on the street it worked just fine. I drove the car home for an hour average speed around 100mph, found an empty lot did launch again and it worked great I made a u turn and attempt to do it again at this point it did not want to engage launch mode.
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      10-15-2021, 09:18 PM   #37
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Quote:
Originally Posted by Magic M4 View Post
So what's the solution , I was just at the track with my m4 first 2 passes everything worked good, after 20 minutes I did a third pass on this pass I set the to 3k and then I let off the brake and held the gas pedal down the rpms dropped to 1k and power was immediately gone after.
I did 2 more passes after this and same outcome . I left the track and did launch on the street it worked just fine. I drove the car home for an hour average speed around 100mph, found an empty lot did launch again and it worked great I made a u turn and attempt to do it again at this point it did not want to engage launch mode.
Maybe your tires got wet or you didn't burnout enough. If LC detects total slip then it comes off throttle as a fail safe. Same thing happened to me when I tried to miss the water box but obviously didn't. As wheels spun and revs hit 7K the gas pedal went dead for a second.
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      10-16-2021, 07:57 PM   #38
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Quote:
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Quote:
Originally Posted by Magic M4 View Post
So what's the solution , I was just at the track with my m4 first 2 passes everything worked good, after 20 minutes I did a third pass on this pass I set the to 3k and then I let off the brake and held the gas pedal down the rpms dropped to 1k and power was immediately gone after.
I did 2 more passes after this and same outcome . I left the track and did launch on the street it worked just fine. I drove the car home for an hour average speed around 100mph, found an empty lot did launch again and it worked great I made a u turn and attempt to do it again at this point it did not want to engage launch mode.
Maybe your tires got wet or you didn't burnout enough. If LC detects total slip then it comes off throttle as a fail safe. Same thing happened to me when I tried to miss the water box but obviously didn't. As wheels spun and revs hit 7K the gas pedal went dead for a second.
Just did a launch on the street and it lost power the same way it did on the street, I was starting to think maybe clutches overheated but it doesn't make sense . I was able to do 5-6 passes back to back a few weeks ago nonissues
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