# Computer controlled launches



## JetBlack330i (Feb 8, 2002)

The e46 M3 w/ SMG has a feature where the computer controls the best launch. Unfortunately, that feature is limited to X number of launches, after which the feature is disabled.
Question: if I were buying a used M3, how do I check how many such launches are left?


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## Mr. The Edge (Dec 19, 2001)

JetBlack330i said:


> *The e46 M3 w/ SMG has a feature where the computer controls the best launch. Unfortunately, that feature is limited to X number of launches, after which the feature is disabled.
> Question: if I were buying a used M3, how do I check how many such launches are left? *


Who said there are a limited number of launches?


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## in_d_haus (Jan 2, 2002)

Wives tale, launch away.


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## Guest (Feb 3, 2003)

*Re: Re: Computer controlled launches*



atyclb said:


> *Who said there are a limited number of launches? *


Even I have heard about this. This is the Euro-only feature allowing full accell w/SMG (which apprently you can hack into on US-spec cars). From what I understand, it DOES have a limited number of uses.

I'll look for authoritative references.


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## Plaz (Dec 19, 2001)

I think it was a limited number of uses before such abuse will void warranty, not that the feature will become unavailable...  but i think that was for the euro-spec. The US-spec launch control (which DOES exist) isn't as harsh on the car (lower RPMs?), and therefore has no such warranty restrictions. It is an undocumented feature of the car.

I may be completely wrong -- this is from sketchy memory. I'll be interested in what TD turns up. (I don't have time to search right now)


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## in_d_haus (Jan 2, 2002)

Plaz said:


> *The US-spec launch control isn't as harsh on the car (lower RPMs?), *


2200 - 2500 rpm launch (US) -vs- 3500rpm Euro


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## Mr. The Edge (Dec 19, 2001)

*Re: Re: Re: Computer controlled launches*



TD said:


> *Even I have heard about this. This is the Euro-only feature allowing full accell w/SMG (which apprently you can hack into on US-spec cars). From what I understand, it DOES have a limited number of uses.
> 
> I'll look for authoritative references. *


there aren't any. It's just been a rumor from the beginning, even some reviews have included it, but no real documentation.


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## Guest (Feb 3, 2003)

http://www.caranddriver.com/xp/Cara...y/200207_shorttake_m3.xml?keywords=bmw m3 smg

Go to the top of page 2 at the link. They say the Euro-only launch mode allows a max of 1 per hour and 30 for the life of the clutch.

Sounds fishy when you stop to think about it. But I knew I had read it somewhere.


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## Mr. The Edge (Dec 19, 2001)

in_d_haus said:


> *2200 - 2500 rpm launch (US) -vs- 3500rpm Euro *


1800 US


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## JetBlack330i (Feb 8, 2002)

Thanks TD. I think I read about it elsewhere, but the CD article is just as good.
How do Europeans check how much life is left?


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## The HACK (Dec 19, 2001)

atyclb said:


> *1800 US *


There are two launch modes (confirmed by Butthead), the 1,800 best possible launch and the 2,500 PEEL OUT mode.

I have two long strips of rubber out near my driveway to prove that. Some people just have no common sense.


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## Plaz (Dec 19, 2001)

The HACK said:


> *There are two launch modes (confirmed by Butthead), the 1,800 best possible launch and the 2,500 PEEL OUT mode.
> 
> I have two long strips of rubber out near my driveway to prove that. Some people just have no common sense. *


:lmao:

No wonder Butthead cords his Conti's with only 5k on 'em.


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## Stuka (Jul 17, 2002)

JetBlack330i said:


> *The e46 M3 w/ SMG has a feature where the computer controls the best launch. Unfortunately, that feature is limited to X number of launches, after which the feature is disabled.
> Question: if I were buying a used M3, how do I check how many such launches are left? *


Here's what happened. When the SMG rumor began to fly for U.S. bound M3's, someone found out that BMWNA was NOT going to make available the LC feature for us dumb 'mericans because of what happened to Audi and the alleged "unintended acceleration.":thumbdwn:

This was posted on Toadfly, and you can imagine the phone calls and emails and whatever else fire storm that it generated toward BMWNA.

BMWNA relented, and decided to not comment out the LC subroutine. They first tried to rewrite S5 to allow LC, which proved to be an exrecise in futility.:rofl: :tsk:

Next they decided to leave everything as is and change the rpm variable from 3600 to 1800. And since the U.S. laws do NOT allow a usable feature to have a pre-determined number of use, BMWNA decided to NOT document this feature in the owners manual. This feature, however, is well documented in the dealers training manual, and was posted on Toadfly by someone who got a hold of a copy of it.:thumbup:

And yes, Butthead has demo'ed the feature to quite a few members on this board, both the burnout mode and the acceleration assistant mode.:thumbup: :bigpimp:

Andy
02 M3 CB/Cloth SMG


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## Pinecone (Apr 3, 2002)

Except acceleration assist (which is what the US version of Launch Control is called) only works in S6.


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## Michael330 (Apr 23, 2002)

Never driven SMG so the question may sound really stupid. How do you actually launch the car. In manual you just add gas as you release clutch and so you choose exactly (hopefully) the moment of movement. In step/auto you let go of the brake and press acceleration pedal. I assume that's how SMG works as well. Or do you actually have to rev the engine to a predetermined point first and then release the brake? If that's the case, the brake acts sort of like a clutch. Can you release the brake and not add any gas and stall the car?


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## Pinecone (Apr 3, 2002)

Michael330 said:


> *Never driven SMG so the question may sound really stupid. How do you actually launch the car. In manual you just add gas as you release clutch and so you choose exactly (hopefully) the moment of movement. In step/auto you let go of the brake and press acceleration pedal. I assume that's how SMG works as well. Or do you actually have to rev the engine to a predetermined point first and then release the brake? If that's the case, the brake acts sort of like a clutch. Can you release the brake and not add any gas and stall the car? *


You release the brake and push the gas and away you go. You cannot add throttle with the brake on for a launch like an auto.

If you release the brake and not add gas, thecar sits there, or rolls if on an incline. The system does not engage the clutch until you add gas.

For harder launches the harder you hit the gas, teh higher the revs before the clutch drops. So you control the clutch engagement with the throttle.


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## JetBlack330i (Feb 8, 2002)

Pinecone said:


> *
> For harder launches the harder you hit the gas, teh higher the revs before the clutch drops. So you control the clutch engagement with the throttle. *


So, there is a delay between the time you release the brake and the time revs climb high enough for the clutch to drop?
I thought that the computer would somehow raise the revs to launch point before you hit the gas...


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## Pinecone (Apr 3, 2002)

JetBlack330i said:


> *So, there is a delay between the time you release the brake and the time revs climb high enough for the clutch to drop?
> I thought that the computer would somehow raise the revs to launch point before you hit the gas... *


It depends on how hard you hit the gas to launch. If you smoothly push the gas, there is an almost imperceptable pause, about the same to less than from you doing the same in a manual.

If you jam the gas, it will take a moment longer and the revs will climb, again just like you would in a manual.

In acceleration assist, the revs climb first, then you release the clutch when you want.


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## Pinecone (Apr 3, 2002)

Actually I was wrong, it is called Acceleration BOost.


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