tuning out the brake override

[drop360]

Can anyone with ECU tuning experience confrim or deny the possibility of tuning out the brake override built into the 2? Any other way to bypass that system?

It seems to be turned off when the clutch is pressed in, so heel-toe works fine. But the brake cuts off accelerator input when driving, so left foot braking is a no go.

I'd really like the ability to do some left foot braking!

 

[Slow Paul]

Maybe I'm crazy, but I can heel and toe just fine in my 2. I usually have the traction control turned off, but I sworn that I've been able to heel and toe with the system on as well too.

 

[drop360]

heel toe works fine, because the clutch is in. When the clutch isn't pressed, the brake will override the gas pedal. But for left foot braking, you want to keep the gas constant and use the brake pedal to induce the oversteer. You can't do that if the gas keeps cutting out when you press the brake.

 

[Slow Paul]

Ahhh! I miss read your post. I'll have to give some left foot braking a shot on the boring commute with absolutely NO ONE on the road.

 

[drop360]

Ahhh! I miss read your post. I'll have to give some left foot braking a shot on the boring commute with absolutely NO ONE on the road.

Hahaha, totally!

I had never done any left foot braking, until a week or so ago when I did a 1 day rally course at Team O'Neil rally school. We spent the whole day with left foot braking. It was amazing - driving into corners fast enough to make the car understeer and start to push, and then feathering the brake to make the tail end kick out and point the car where you want to go. More brake, more oversteer, less brake, less oversteer. Once I got it down, it was pretty simple, and very awesome.

My biggest learning bump with the technique, was that I had a hard time not lifting off of the gas. If you lift off, the technique doesn't work in a front wheel drive. And that's my issue with the brake override on the 2. It's just like lifting off the gas, even if you don't. I want to practice my rally techniques!

 

[zps2004]

I just tried it in my car and power was not cut while applying the brake. I thought I did it before with no problems, but I didn't want to post anything until I confirmed it. In my car I can left foot brake no problems.

 

[drop360]

I just tried it in my car and power was not cut while applying the brake. I thought I did it before with no problems, but I didn't want to post anything until I confirmed it. In my car I can left foot brake no problems.

Nice! That means there are 2011 Mazda 2's that have it, and some that don't. I read it cost about $50 to add it to the vehicle. So, if it's cheap (can't consist of much) and some have it and others don't, maybe it will be easy to get rid of!

 

[drop360]

I just tried it in my car and power was not cut while applying the brake. I thought I did it before with no problems, but I didn't want to post anything until I confirmed it. In my car I can left foot brake no problems.

You didn't happen to have by-passed the clutch switch, did you? Since there is no brake override with the clutch pressed in, I'm wondering if the switch is by-passed, if that might also cancel out the brake override... I'm not excited by the idea of no clutch switch, but just trying to figure out my options.

 

[zps2004]

No I don't. Only thing I can think of is that my car is a touring, but even that shouldn't be the reason it is different for our two cars.

How do you know that the engine is being cut when you hit the brake pedal?

I know it works on mine because not only is the engine still loaded when I hit the brake, but if I hit the brake and the gas at the same time, then lift off the gas the car brakes harder since the no acceleration from the engine is canceling out the braking.

 

[drop360]

No I don't. Only thing I can think of is that my car is a touring, but even that shouldn't be the reason it is different for our two cars.

How do you know that the engine is being cut when you hit the brake pedal?

I know it works on mine because not only is the engine still loaded when I hit the brake, but if I hit the brake and the gas at the same time, then lift off the gas the car brakes harder since the no acceleration from the engine is canceling out the braking.

I tested it out to see if I had the brake override system. Driving down the road (with no one behind me), I'd get the rpm's up to a good audible level, keep the gas steady, and apply the brake. Engine noise goes away, rpm's drop, all power cut - the car brakes and puts the engine in idle. When I release the brake there's a delay of maybe 1/2 a second to a full second before the engine responds and revs up out of idle. This is all with my holding the gas steady and never lifting off.

It's pretty lame...

 

[zps2004]

Strange.

 

[zps2004]

Ok, so on the way to work I got it all figured out. If you are on the gas, then you hit the brake at the same time for 2.5-3 seconds it cuts the engine. The reason I didn't notice this was because from what I know when you left foot brake it is typically to reduce the amount of time your not on the gas, basically taking the time it takes to move your foot from the brake to the gas out of the equation, so you have a seamless change. This way you are barely on both at the same time. It is also used to balance the car if needed in a corner and IMO if you need to hit both for more than 2.5-3 seconds to balance the car then your doing something else wrong like going in to fast or your car really isn't balanced correctly. If you are on the gas and you hit the brake then release it then get back on your are fine. Only 2.5-3 seconds of consecutive use makes the engine cut out.

Now being an engineer I looked into other similar scenarios. If you are braking for over 2.5-3 seconds then hit the gas you have throttle. Again doing it this way you need to hit both for over 2.5-3 seconds before it cuts the engine. If braking and you get on and off the gas it is fine as long as you don't hit both for more than 2.5-3 seconds.

Also taking the traction control off doesn't make a difference.

Yay I think we finally figured it out.

 

[drop360]

Ok, so on the way to work I got it all figured out. If you are on the gas, then you hit the brake at the same time for 2.5-3 seconds it cuts the engine. The reason I didn't notice this was because from what I know when you left foot brake it is typically to reduce the amount of time your not on the gas, basically taking the time it takes to move your foot from the brake to the gas out of the equation, so you have a seamless change. This way you are barely on both at the same time. It is also used to balance the car if needed in a corner and IMO if you need to hit both for more than 2.5-3 seconds to balance the car then your doing something else wrong like going in to fast or your car really isn't balanced correctly. If you are on the gas and you hit the brake then release it then get back on your are fine. Only 2.5-3 seconds of consecutive use makes the engine cut out.

Now being an engineer I looked into other similar scenarios. If you are braking for over 2.5-3 seconds then hit the gas you have throttle. Again doing it this way you need to hit both for over 2.5-3 seconds before it cuts the engine. If braking and you get on and off the gas it is fine as long as you don't hit both for more than 2.5-3 seconds.

Also taking the traction control off doesn't make a difference.

Yay I think we finally figured it out.

That sounds like what mine does, also. But here's the issue...

One aspect of left foot braking is to reduce the time between off gas - on brake - off brake - on gas. But my recent time at the Team O'Neil rally school introduced to me another type of left foot braking. I think I described it in a post earlier in this thread. But it was a constant gas, feather the brake to induce oversteer. This can't be done with the brake override. Unfortunately, as I had a good deal of experience with at Team O'Neil, if you lift off the gas, the technique stops working.

I'll be honest. I don't know all of the in's and out's of it. The instructors told us that we needed to stay steady on the gas in a front wheel drive, but in an all wheel drive, you would need to lift off the gas for the same technique to work. We only got to drive front wheel drive, so that's all I can really comment on.

 

[zps2004]

Warning on the below. I don't know how much you know about car dynamics so I explain things below. If you already know then great.

I see what you are saying, but this is where I am saying that if you have to do that your car isn't tuned that well. Typically in a FWD car you lift off the gas to get the car to rotate. Lift throttle oversteer is what it is called. Basically it takes weight off the back and onto the front. Thus the front has more grip the rear has less, the car oversteers.

If you do it while braking it is called trailbraking. That is off the principal of the braking force being in front of the CG of the car, so the braking causes a natural instability. Just like having a pencil on a table laying flat and pushing one end. It is hard to push it straight without it turning. Same as trailbraking.

I you can use left foot braking to quickly transfer the wright when you are right on the edge of traction. I do it in my miata sometimes when I know lifting off the gas will cause a lot of oversteer so by left foot braking I can make finer adjustments.

I have never heard of someone relying on left foot braking to get their car to rotate.

 

[drop360]

I know very little about driving technique. But my understanding of what we did that day is as follows:

With lift throttle oversteer, it seems like you would lose speed because now only your momentum is carrying you forward, and you would be experiencing engine braking in addition to friction and be slowing down. By feathering the brake pedal with left foot braking, you acheive the same forward shifting of weight which both lets the rear slide around, but also gives the front more traction. Since you never released the gas, your front wheels are always pulling you forward, negating any loss of speed from the brake feathering.

Trail braking was described to us as this - heading into a turn at a speed faster than will allow you to make the turn, you apply threshold braking in a straight line to srub as much speed as possible. When it comes time to enter the turn, you still have too much speed to make the corner. You're also using all available traction for braking, and there is nothing left for turning. So, as you turn the steering wheel, you start to let off the brake pedal. You're basically changing the ratio of braking:turning, from 100:0, to 99:1, 98:2, 97:3, etc all the way to 0:100. This allows you to carry the largest amount of speed into and through tight corners, while still being able to slow yourself just enough to retain traction. You start with full braking, and slowly trail off the brake pressure, thus the name trail braking.

Both of these techniques were done on gravel. I don't know if that changes anything when on tarmac. I also fully admit that my understanding of the techniques may be wrong!

 

[zps2004]

It does the same thing. I just don't see it being used. Most of the time when you get into a corner you balance the car with the gas only because hitting the brake at all would slow you down. Lifting off or trail braking is just to get the car to turn into the apex.

I was thinking about the gravel VS pavement thing as well. I am thinking that being able to do it on the gravel might be useful, I need to think about different scenarios. I wouldn't know about gravel, but on pavement I know prolonged braking with gas+brake is never really used.

To the original point I am 99% sure Mazda put it in there to prevent an abuse situation. Gas + braking can be rough on axles.

 

[drop360]

To the original point I am 99% sure Mazda put it in there to prevent an abuse situation. Gas + braking can be rough on axles.

No, they put it there because the people died in the Toyotas. Now everyone is jumping on the bandwagon.

 

[zps2004]

We thought about that, but this version of the 2 has been sold since 08 so I don't know if that was really exposed much back then. They might have added it in for the US market though.

 

[drop360]

http://www.mazdainthenews.com/mazda-to-start-adding-brake-override-to-new-models/

 

[Sweetums]

I know this is an old thread, but I found some pertinent information!

I have a 2011 Mazda2 Sport, and it does unfortunately have the Brake Override System. This method does however work on my car.

This was found on http://forum.miata.net/vb/showthread.php?t=424402

Disabling of BOS

If the brake pedal and the accelerator pedal to be depressed together, operation of the brake override system can be prevented, if necessary.

Disable brake override operation conditions

If the following conditions are met for 10 s within 30 s after switching the ignition ON (engine off), the brake override system is disabled until the activate brake override operation conditions are met.

■Vehicle speed: 0 km/h {0 mph}

■Accelerator pedal fully depressed

■Brake pedal depressed

Activate brake override operation conditions
Cycling the key off and back on will re-activate the brake override operation conditions.