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Cannot power brake to launch????

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Old 02-01-2006, 06:12 PM
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Default Cannot power brake to launch????

Is there something in the PCM that limits power when the brake is on or when you are not moving? I try and power brake and I have no power. It will not try and build rpms or even strain the brakes. As soon as I start rolling I have a rush of power??
Old 02-01-2006, 06:26 PM
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I am not sure why you are having a problem. My truck will stall up to about 2500 rpm and yours should as well. If I hold it at part throttle opening I have seen over 4 psi of boost before launching at 2500 rpm. I would ask Allen if he can help you out with this. If it is in the tune I am sure he will be able to help you out. I think that something is wrong with your tune or throttle linkage and I hope someone can help you out with it.
Good luck
Old 02-01-2006, 07:13 PM
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i think it probably is in your tune, mine did the same thing and allen worked with me to correct it, but since ive got the intercooler my truck really came to life and will roast the tires into oblivion at 6#s of boost, you need to get some values for him to help dial in your tune- L-trims at steady speed, I.A.T.s and timing at W.O.T . ,Knock Retard at W.o.t. and O2s should be around 920mv. im sorry to post if you already know this, just some thoughts on your prob, good luck!
Old 02-01-2006, 07:58 PM
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Mine does the same thing. It just bogs down and wont build rpm's.
Old 02-01-2006, 08:37 PM
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I read somewhere (on this site) that GM was working on programming to do exactly what your describing. As you build rpm but don't register tire spin (brake stalling) the PCM pulls timing. I would think it can be tuned out but I was under the impression it wasn't in the PCM's yet. I thought it was coming in 06+ but maybe they snuck it in early.
Old 02-01-2006, 08:47 PM
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I don't see a stall in your sig. Without one it will not build any boost because the stock converter will not let the motor rev high enough.
Old 02-01-2006, 09:10 PM
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The electronic throttle control(ETC) vehicles have "Brake Torque Management"(BTM) which will limit throttle opening if your foot is on the brake. This can be disabled in the tune.
Attached Thumbnails Cannot power brake to launch????-btm.jpg  
Old 02-03-2006, 04:34 AM
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so does that mean I cant power brake too? does that also mean I cant do a burnout?
Old 02-03-2006, 08:25 AM
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Originally Posted by dkubricht
so does that mean I cant power brake too? does that also mean I cant do a burnout?
There are also several other "Torque Management" and "Abuse Management" parameters in the factory calibration that limit power output under various conditions. WOT launches would be one of those conditions.
Old 02-03-2006, 08:52 AM
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Originally Posted by dkubricht
so does that mean I cant power brake too? does that also mean I cant do a burnout?
Mine is still stock no tune only mod is exhaust. I've never had a problem. What I do is apply brake softly apply gas as the back tires have forward momentum apply alot more pressure the the brakes and you'll be smoking'em too.
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