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Old 02-23-2010, 12:32 AM
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Launch control question.....

Thanks for your input....

I am wondering if my launch control is activating properly. I am setting up properly, and am getting the chequered flag, but, I am having to REALLY stand hard on the brake, to prevent the car from jerking forward a few feet, once I floor the accelerator. It's as though "launch control" is simply "brake torquing" the car.
This is in marked contrast to my M3. When I engage launch control on it, the revs build to 5500rpm, with NO brake. In fact, in the M3, it will actually roll backwards or forwards, as there is no drive being applied, whatsoever.
I realize that the X6 is an automatic, but this just doesn't seem right. In the sole video I could find, launch control in an X5M just seemed to rev to about 2500rpm, and then just "go".
In ours, it seems like all the car can do, just to remain stationary. I know there is no clutch to dump in the X6, but this just seems so brutal on components.

Can anyone confirm that this is actually what happens with launch control?? - i.e. that there is actually drive being applied to the wheels while you are holding the brake down - that in effect, you are simply "brake torquing" the car? If that's the case, I won't be using the launch control feature any more, that's for sure.
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Old 02-23-2010, 01:20 AM
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Quote:
Originally Posted by TTBear View Post
Thanks for your input....

I am wondering if my launch control is activating properly. I am setting up properly, and am getting the chequered flag, but, I am having to REALLY stand hard on the brake, to prevent the car from jerking forward a few feet, once I floor the accelerator. It's as though "launch control" is simply "brake torquing" the car.
This is in marked contrast to my M3. When I engage launch control on it, the revs build to 5500rpm, with NO brake. In fact, in the M3, it will actually roll backwards or forwards, as there is no drive being applied, whatsoever.
I realize that the X6 is an automatic, but this just doesn't seem right. In the sole video I could find, launch control in an X5M just seemed to rev to about 2500rpm, and then just "go".
In ours, it seems like all the car can do, just to remain stationary. I know there is no clutch to dump in the X6, but this just seems so brutal on components.

Can anyone confirm that this is actually what happens with launch control?? - i.e. that there is actually drive being applied to the wheels while you are holding the brake down - that in effect, you are simply "brake torquing" the car? If that's the case, I won't be using the launch control feature any more, that's for sure.
The same thing happened to me the first time and realized I didn't have MDM function on

1. Set M function
2. Make sure MDM traction function is on
3. Sport mode on transmission
4. 1st gear manual.

I've felt the lurching when one of these thing wasn't done but when it works properly there is no lurching forward with brake depresssed and accelerator floored. Strange though that you have the checkered flag...
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Old 02-23-2010, 02:35 AM
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It seems to me that with an automatic transmission, there are only two options for the transmission while you are revving it up. It can be working against the torque converter (producing a lot of heat) or it can be in neutral, in which case releasing the brake would then slam it into gear at high revs. That would be brutal as well. I think it is far more likely that it is in fact working against the torque converter.

At the end of the day, it is an automatic transmission.
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Old 02-23-2010, 04:23 AM
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Yes, you have to mash on the brakes to keep the car from moving forward for launch control. It's just fancy brake torquing.

I also wonder how much wear it's putting on the torque converter, but then again popping a clutch at high revs in a manual is also hard on the components.
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Old 02-23-2010, 10:18 AM
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^^ is correct, though following the launch control sequence (seeing the flag) tells the X to shift up through the gears at/near redline so long as your foot is on the floor.

In any other scenario where you're in M/S mode and you manually shift into 1st, the truck will not shift up for you even at redline.

I don't think the ///X is the only vehicle that uses this methodology.
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Old 02-23-2010, 11:56 AM
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Thanks everyone.

Yep, I do have it in MDM mode (programmed the M button to enable everything I need to, in order to facilitate launch control).

It's good to know that it is likely functioning as intended. I guess I was just hoping for something somewhat more advanced than simply brake torquing, but c'est la vie.

Don't think many launch control launches are on the cards for me, then! I guess I'll just have to be satisfied with 4.3 second 0-60 runs, instead of the 4.1 that Car and Driver obtained

Cheers!
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