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View Full Version : Left foot braking=Power cut?



sholitz
10-03-2009, 12:36 PM
I'm wondering if anyone has any experience with left foor braking in our cars. I use left foot braking alot at autocross and in general for setting up a corner or mantaining yaw angle, but have noticed a clear issue that I've never seen in another car.

With both the Brake depressed (With a bit of force) at the same time as the accelerator (Pinned) It shuts power down in a hurry. Seems to be some "saftey feature" or somthing. Anyone know how to disable it? Or even what system it is? Cause boy it's slowing me down...

99blueb5
10-03-2009, 12:46 PM
what do you mean by "shuting down" like engine dies or the car nosedives? or?

sholitz
10-03-2009, 12:48 PM
Nose dives....HARD. It feels terrible.

(Oh I drive a 01 Avant FYI (if that somehow helps.))

getslideways
10-03-2009, 01:03 PM
yup welcome to drive-by-wire, its sucks sometimes, i haven't heard of anyway to change that feature

mine does the same thing (2000) if you are on the brake and the gas at the same time it cuts the throttle completely. Maybe it thinks the throttle is stuck and you are trying to stop??? who knows, but no brake boosting thats for sure. It only cuts throttle if you are moving though, you can still power brake it, so maybe if you could trick the car into thinking its not moving somehow... but then that would probably freak 10 other sensors out lol

.Mad Hatter.
10-03-2009, 01:07 PM
hmmm...i dont tend to left foot brake in auto-x...i will try tomorrow and see how it handles.

Dan[FN]6262
10-03-2009, 01:13 PM
for some reason there is a dude with a B6 A4 that has a video on here of him brake boosting. i think it was MMMBOOST (not sure entirely). there were ppl talking about brake boosting in the B6 section and how to get around the safety switch and he posted saying that he could brake boost. no one believed him of course, so he went and took a video and posted it. he has no idea why he can. if i remember correctly he has APR stg3 kit

sholitz
10-03-2009, 01:18 PM
Wow DUH....Thanks for the obvious answer...lol.

As far as autocross goes man there was a stock Jetta 2.5(H-stock) killing me out there every time. Turns out he had been left foot braking. I learned how, and soon got my balls back. It was a lot to get used too untill I started doing it on the street. Good luck!

sholitz
10-03-2009, 01:20 PM
Shank210;4319946']for some reason there is a dude with a B6 A4 that has a video on here of him brake boosting. i think it was MMMBOOST (not sure entirely). there were ppl talking about brake boosting in the B6 section and how to get around the safety switch and he posted saying that he could brake boost. no one believed him of course, so he went and took a video and posted it. he has no idea why he can. if i remember correctly he has APR stg3 kit

I'll check it out. Thanks

UCFQuattroguy
10-03-2009, 06:30 PM
yea...the DBW cars shut the throttle plate if you brake and apply throttle at the same time. Not going to mention any names (not sure if they want it advertised), but some of the tuners offer a version of their tunes w/LFB capabilities.

biketsai
10-03-2009, 09:06 PM
It will work if you do it for a short amount of time. IIRC, with the DBW, it will work if you press the brake first then apply gas it wont cut out as quick but if you do the opposite (gas and then press brake), it wont turn out too well.

Pete@IE
10-03-2009, 09:55 PM
For autocross, you can pull out the brake switch and it will left foot brake just fine. For those wanting to highway roll race or whatever, try this: take foot completely off the gas pedal... Put your left foot on the brakes, then go back on the gas. For whatever reason, the ECU doesn't care about it as long as the brakes were on before the throttle.

walky_talky20
10-03-2009, 10:25 PM
I think this "safety feature" stems from the lawsuits against Audi in the late 80's. At that time, Audi was involved in lawsuits totaling over 5 billion dollars for "unintended acceleration" of their Audi 5000 models. There were a few incidents where drivers accidentally hit the gas instead of the brake - inadvertently causing the death of a child. There was even a "60 Minutes" report that blew the whole thing way out of proportion. This was really no fault of the car, and was later determined by the NHTSA to be "pedal missaplication". On the 5000's the brake and gas pedals were slightly closer together than other cars (possibly for easier "heel-and-toe" action). These lawsuits also led to Audi renaming the 5000 model to "100" in 1989.

You can read more here: http://www.businessandmedia.org/specialreports/2008/MediaMyth/NineWorst/NineWorstStoriesFull4.asp

With the drive-by-wire system. If you mash the pedals and hit both, the throttle closes and the car stops. I've also noticed that if you then remove your foot from the brake the throttle will nicely "fade" back in. Fancy.

mike-2ptzero
10-03-2009, 10:32 PM
As Pete said, you have to hit the brake first and then go wot. You still have a very small window till the ECU over rides.