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Discussion Starter #1
I don't know if anyone else has had this problem, but I've ran into it with my old MZ3 and the current MS3.

You know when you're stopped at a red light and you mash the brake pedal all the way? Like really hard. Then you lift slightly (about .5") and the pedal returns but you can push back down and there is no resistance? You can just slap the pedal back and forth.

Well this happens occasionally during autocrosses where I dig real hard on the brakes, lightly lift as I turn-in (trail brake), but the full brake pressure is still on. The pedal just slaps back and forth and the car keeps slowing in ABS. The ability to modulate under heavy braking is completely gone.

Now I've adapted to this where it doesn't happen as often by using lighter pedal pressure but I know I'm losing time because I just can't attack the brakes like I have in other cars.
 

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Braking

Not sure if this relates, but sounds a little like "ice mode" suffered by some cars during autocross braking conditions.

My current MZ3 does not have ABS, but never had what you describe on my '08 MZ3 Hatch. But then, I don't brake much anyway.......:roll:
 

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Mine does this too. I notice it the most going into the stop box where I'm really bringing the car down. On course it's a rare occasion, but I definitely have the same issue. I wonder if it's an issue with the ABS, it engages and takes a second to realize 'wait he isn't pushing the brakes anymore.'

Can we legally disable ABS by removing the fuse? IIRC we can only disable it electronically, but what does that entail?
 

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fast or hard braking activates more "brake assist" or something of that nature.
 

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Can we legally disable ABS by removing the fuse? IIRC we can only disable it electronically, but what does that entail?
I'm not showing an allowance for ABS fuse removal either, at least in Street and Street Touring.

I'm not sure how involved it would be to disable it electronically but I imagine you need software to access and modify parameters within the ECM, perhaps ask Joe at Dynotronics and see if he has the ability to turn off the ABS and if he would be willing to do so. Off the shelf programmers have no such feature, probably because it's not commonly asked for and also there would be some inherent liability that would the company would not want to assume.
 

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I'm not showing an allowance for ABS fuse removal either, at least in Street and Street Touring.

I'm not sure how involved it would be to disable it electronically but I imagine you need software to access and modify parameters within the ECM, perhaps ask Joe at Dynotronics and see if he has the ability to turn off the ABS and if he would be willing to do so. Off the shelf programmers have no such feature, probably because it's not commonly asked for and also there would be some inherent liability that would the company would not want to assume.
I know on some vehicles, it was as simple as unplugging a wheel speed sensor. Of course, I think that causes the 3 to royally freak out...
 

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I know on some vehicles, it was as simple as unplugging a wheel speed sensor. Of course, I think that causes the 3 to royally freak out...
I hear ya, additionally there is no provision in the rule book stating it's ok to unplug wheel speed sensors.
 

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Discussion Starter #9
13.9.G (street)
On cars without the ability to turn off electronic stability control and/
or traction control (ESC/TC) from the manufacturer, modifications to
defeat the ESC/TC are permitted. These modification are limited to
altering the inputs to the ESC/TC processor (e.g., removing fuses,
unplugging yaw or steering angle sensors, altering signals) and may
serve no other purpose. Any codes or error lights resulting from ESC/
TC modifications are permitted.


So you can only unplug the steering angle sensor to defeat traction control, and that's only if there is no way to electronically disable TC.

14.3.D (street touring)
Original equipment ABS braking systems may be electrically disabled but may not be removed or altered in any other way.


So if you can get at it from the OBD or you can magically turn it off on you car, you're stuck.
 

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Why not just unplug the ABS module?
 

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Why not just unplug the ABS module?
Because the rules are very specific about what is allowed and he wants to adhere to those standards. Someone can't just go unplugging whatever they feel like unplugging, particularly when they're a current Solo National champion like the OP is.
 

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I wonder if we can side step this issue all together. Does someone want to pull the abs fuse and then do some brake testing to see if this actually fixes the threshold issue?

I have a non-scca event this weekend, I'll pull it and report back. It doesn't happen to me all that often though so I may not see a difference.
 

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Does anyone know for a fact we can pull the ABS fuse all willy-nilly and be alright?

As you know the car uses the ABS sensors for quite a bit, I'm just wondering if the ABS fuse is only the brake purpose of those sensors.

Otherwise you'll lose power steering along with it as well (which is no bueno on a power rack), and your speedometer, and a few other lesser essentials.
 

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Discussion Starter #15
From my 5 minute research it looks like all but the 2.0 Mazda 3s have Electronic Brake Distribution. This could cause a huge issue if we disable ABS. I've autocrossed an E36 for an entire season without ABS. You know when Miatas are not setup properly and they lock the inside front into everything? Like that but way worse.
 

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Looks like it's controlled by the ECU - I assume - according to the wiring diagrams.

One section of the ABS control module is handled off to what it refers to a CAN bus to "data link connector-2" which I can only assume is ECU related.

That said, looking into it... this is a sketchy test, but I'm wondering if you ground out or cancel out the connectors on the plug?

The harness that connections has what looks like can be 26 connectors.
There is a wire, BR/G on top, 2nd to far right, IS that data connector.
There should be a wire below it which would be the second wire.. but it doesn't show anything, just says "*" for the wire color.

As a warning, this is coming from an 04 manual, for you have a speed, it may [may] be different.
 

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Thinking about it on a side note; isn't this the exact same issue the Playboy series Spec Miata guys have?

Isn't that why they tap the brakes before going into a turn to "reset" the system?
If it is the same case, and those guys haven't come up with a solution; I doubt we ever will.
 

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Discussion Starter #20
Isn't that why they tap the brakes before going into a turn to "reset" the system?
Hmmm, so I'm assuming that fools the computer into thinking it's not an emergency stop scenario? I'll try that in the 3 and see if it makes a difference.
 
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