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Interesting stuff, cyow5. Very cool that you program ABS systems for race cars. I had no idea how sensitive they were (brake pads even) and I like your broom analogy, haha.

Are ABS systems usually controlled from the ECU? Sorry if that is a dumb question but I am new to this. Because if so I wonder if you could switch ecu's (or?) from a wrecked car that you knew didn't do the ICE mode "thing" (like my Exige vs my former Elise) and solve the issue without much fuss.

Just a thought.

Whatever controls the programming it sees like there must be different settings from the factory on our cars otherwise more people would experience it more often (I may be wrong but it seems like not that many people have had it happen). That could explain the difference between cars going into ICE mode, or not, under very similar circumstances (stock brakes, LSS wheels, R888's on both cars in my case).
 

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Interesting stuff, cyow5. Very cool that you program ABS systems for race cars. I had no idea how sensitive they were (brake pads even) and I like your broom analogy, haha.

Are ABS systems usually controlled from the ECU? Sorry if that is a dumb question but I am new to this. Because if so I wonder if you could switch ecu's (or?) from a wrecked car that you knew didn't do the ICE mode "thing" (like my Exige vs my former Elise) and solve the issue without much fuss.

Just a thought.

Whatever controls the programming it sees like there must be different settings from the factory on our cars otherwise more people would experience it more often (I may be wrong but it seems like not that many people have had it happen). That could explain the difference between cars going into ICE mode, or not, under very similar circumstances (stock brakes, LSS wheels, R888's on both cars in my case).
Whatever controls the programming it sees like there must be different settings from the factory on our cars otherwise more people would experience it more often (I may be wrong but it seems like not that many people have had it happen). .
Have been watching ice mode threads (and complaints) for about 10 years. This is a prevalent problem. I actually would hazard that people DO experience it quite often. But it's a track phenomenon, and my own anecdotal observation is that it increases as people really begin hitting the brakes hard, and have modded the car with some aftermarket combination of wheels, tires and/or brakes. If it doesn't seem commonplace, it's perhaps because there's no fix other than behavior modification (avoiding triggers; mitigating effects), and folks have just given up trying to resolve a mechanical fix that preserves ABS.
 

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Car-chitect, the ABS logic is in the ABS module itself, it sits in the front left wheel arch.

Much as ice mode annoys me, the ABS system in the Elise is quite good. When engaged in regular mode, it does a fantastic job braking, almost as good as perfectly executed threshold braking. You know crappy ABS when you hit it - the car, pedal and steering wheel start shaking.

In my case, I'm running carbotech XP12 pads, which have a much higher friction coefficient than stock, and I'm running soft compound racing slicks, which have a far higher coefficient of friction than stock tires. The net result is that the normal rate of wheel deceleration is far higher than something you would see on the street, and yet, the ABS system handles it just fine the majority of the time. I moved my brake bias a little bit forward by using less grippy rear pads, and the incidence of ice mode became less common.

Like cyow5, I've also written control system code using limited sensor input, and it's a challenging problem! ABS is one thing, but today, stability control is mandatory, and getting that stuff working is both really cool and a bit of black magic - accelerometers, gyroscopes, high rate wheel speed sensors, combined with a model of what the car should be doing versus what all the sensors are telling it. Fun stuff :)
 

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marcinr, very cool, I'm always impressed with how much knowledge there is on this site!

So is the ABS module like a mini computer that only handles brake/wheel sensor input? Is it something that could be easily switched from one car to another? Or are they really just all exactly the same from car to car so it wouldn't make sense to even bother, and maybe I just haven't had the identical situations in my 'S as in my Elise?

Not being a coder I am lost as to how this all works, but I definitely get that there is a lot of black magic that goes into it. These dynamic stability control systems where the inner front wheel is progressively braked to help turn-in when understeer is detected, etc. -very cool and interesting stuff. Magnetic ride height systems, progressive lowering of ride height at speed, etc. I can only imagine the arrays of sensors needed to communicate and safely react to any possible situation, with lots of testing involved, but still on a budget. Except in formula 1, haha. Though there, even though all of this has been outlawed, even more complicated code must be needed for managing the ERS, KERS, braking, diff controls (corner entry, mid corner, corner exit), hundreds of sensors, etc. Wow!

And agreed about the Lotus ABS, it is really good if you don't hit ICE mode. I have super crappy ABS in my pickup, always locking rears and making the front useless. I think it must be set for a fully loaded truck (makes sense because with more weight you'd need it more) but still no fun when you don't want it and the truck is empty.

So the Lotus is great deep into a corner, even on stock brakes and R888's :)
 

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Interesting stuff, cyow5. Very cool that you program ABS systems for race cars. I had no idea how sensitive they were (brake pads even) and I like your broom analogy, haha.

Are ABS systems usually controlled from the ECU? Sorry if that is a dumb question but I am new to this. Because if so I wonder if you could switch ecu's (or?) from a wrecked car that you knew didn't do the ICE mode "thing" (like my Exige vs my former Elise) and solve the issue without much fuss.

Just a thought.

Whatever controls the programming it sees like there must be different settings from the factory on our cars otherwise more people would experience it more often (I may be wrong but it seems like not that many people have had it happen). That could explain the difference between cars going into ICE mode, or not, under very similar circumstances (stock brakes, LSS wheels, R888's on both cars in my case).


ABS has its own dedicated controller within it and it only has a little bit of communication to the ECU. I should also point out that I am speaking in generalities as I have never tuned this ABS or delved into how it works really deep. I could see a manufacturer with deeper pockets having different calibrations for the different models, especially LSS vs non-LSS and stuff like that where the wheel inertia changed a lot, but I wouldn't be surprised if Lotus just found a single calibration that was 90% right for all the different platforms and stuck with that.

ABS is definitely one of those "how hard can it be?" kinda situations until you start really going through what it takes. For example, how fast is the car actually going? If you lock all four wheels at once, the wheelspeed sensors say the car is stopped. You can augment that with an accelerometer and see that it is still sliding, but those are noisy and drift over time very badly. How the ABS handles this problem is one of the major tuning tools and that is built on the idea that you know the car can only decelerate at a certain rate, say 1g. But what if you add sticky tires and a massive wing? Now it can decelerate at 1.5g but the ABS thinks that isn't possible and starts questioning the speed sensors. Okay, so we recalibrate it for 1.5g max decel, but you head out on cold tires, so now it locks up way too easily. This is why racecars have 12 position dials for the ABS, but street cars have to try to guess all these things as best they can.

I found I only went into ice mode with the R888s but not with my current BFG Comp 2s or even all-season Conti DWS. So the least grippy tires have gone into ice mode less, so my theory (at least only from my own, limited experience) is that the R888s had much less grip when they were not properly warmed up. Cold, as in less than 60F, they felt harder and less grippy than my more recent tires. The R888s could've been past their useful life, too. That plus my bitey pads fits with how I understand the ABS to handle decel rates.
 

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I've experienced the ice mode a few times on the street: usually it happens when a stop light changes abruptly and I try to brake too hard over rough pavement. The lss wheels and springs with dunlop direzza tires just seem to bounce over the pavement. In these situations, my other car has no problem (not even engaging the abs), but the lotus does not inspire confidence. That hard pedal and feeling of lost brake performance makes me feel like it's safer to just not even try to stop.
 

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I've experienced the ice mode a few times on the street: usually it happens when a stop light changes abruptly and I try to brake too hard over rough pavement. The lss wheels and springs with dunlop direzza tires just seem to bounce over the pavement. In these situations, my other car has no problem (not even engaging the abs), but the lotus does not inspire confidence. That hard pedal and feeling of lost brake performance makes me feel like it's safer to just not even try to stop.
Funny enough, I haven't seen ice mode since I left Michigan ;) Granted, that's about the time I changed tires, but I still like blaming that state for everything, haha
 

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So I am wondering if there has been any kind of survey about whether the '07 and later cars experience ICE mode less than the '05's, indicating the programming may have been changed in the ABS control module and therefore if you switched modules to a later one you could reduce ICE mode. A brief search, and reading through some other ICE mode threads, found nothing yet.

From acslater's description, that is what I did in my '07 Exige S (it felt much more normal, smoother, not panicky) and I notice he has an Exige in his avatar, but what he describes as "pushing through" did not/could not happen in my '05 Elise and it looks like marcinr, cyow5, and Obeisance all have '05 Elises.

Any thoughts? It might be a hard survey to do since there are so many more '05's than later cars...
 

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So I am wondering if there has been any kind of survey about whether the '07 and later cars experience ICE mode less than the '05's, indicating the programming may have been changed in the ABS control module and therefore if you switched modules to a later one you could reduce ICE mode. A brief search, and reading through some other ICE mode threads, found nothing yet.

From acslater's description, that is what I did in my '07 Exige S (it felt much more normal, smoother, not panicky) and I notice he has an Exige in his avatar, but what he describes as "pushing through" did not/could not happen in my '05 Elise and it looks like marcinr, cyow5, and Obeisance all have '05 Elises.

Any thoughts? It might be a hard survey to do since there are so many more '05's than later cars...
They changed suppliers for the ABS at least once, but I don't have the specifics right in front of me. There very well may have been calibration changes along the way, too. I believe the switch from Kelsey-Hayes to Bosch was pretty late though towards the end of the federal run, so I'm not sure if those even made it here. Reading other threads on here, it seems the Kelsey-Hayes system is pretty crude and lacks some of the extra sensors like accelerometers that really help improve control. Funny enough, one thread suggested buying a Bosch M4 ABS kit which is what I used to calibrate. Now that would be a sweet retrofit, haha. This thread also mentions a variety of years all having the problem, so it could be a natural consequence of not having the best system.

http://www.lotustalk.com/forums/f91/very-scary-brake-problem-today-ice-mode-victim-70922/
 

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So I am wondering if there has been any kind of survey about whether the '07 and later cars experience ICE mode less than the '05's, indicating the programming may have been changed in the ABS control module and therefore if you switched modules to a later one you could reduce ICE mode. A brief search, and reading through some other ICE mode threads, found nothing yet.

From acslater's description, that is what I did in my '07 Exige S (it felt much more normal, smoother, not panicky) and I notice he has an Exige in his avatar, but what he describes as "pushing through" did not/could not happen in my '05 Elise and it looks like marcinr, cyow5, and Obeisance all have '05 Elises.

Any thoughts? It might be a hard survey to do since there are so many more '05's than later cars...
From a Lotus engineer: "The front brakes are still working just as well as before the valve closed and will give more braking if the pedal effort is increased, while with the rear brakes working as hard as they can the braking is NOT affected. The problem is the driver feels like braking is reduced (even though it is not) because of the change in pedal feel. If the driver continues to push hard on the pedal, the car will continue to slow as fast as it possibly can in the circumstances."

The full text is a good read to understand what is going on: http://sector111.blogspot.com/2013/09/lotus-ice-mode-explanation.html

EDIT: Looks like someone else already posted this and that you guys don't think it's accurate. I think it's accurate, but I think you really do have to exert more force to get the same amount of braking (as if the boost is gone). That's what it feels like to me; when it happens, I push through hard and I'll usually save the corner but run a little deep.
 

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The description from the blog on Sector111 and the behavior posted are definitely not in agreement. Hopefully Shinoo will chime in on his source.
 

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They changed suppliers for the ABS at least once, but I don't have the specifics right in front of me. There very well may have been calibration changes along the way, too. I believe the switch from Kelsey-Hayes to Bosch was pretty late though towards the end of the federal run, so I'm not sure if those even made it here. Reading other threads on here, it seems the Kelsey-Hayes system is pretty crude and lacks some of the extra sensors like accelerometers that really help improve control. Funny enough, one thread suggested buying a Bosch M4 ABS kit which is what I used to calibrate. Now that would be a sweet retrofit, haha. This thread also mentions a variety of years all having the problem, so it could be a natural consequence of not having the best system.

http://www.lotustalk.com/forums/f91/very-scary-brake-problem-today-ice-mode-victim-70922/
So I am wondering if anyone has ever changed ABS modules from a car that works "better" to a car that is worse (ICE mode more easily and frequently) and if that would even work. I feel like there could possibly be an easy and not too pricey solution to most of this problem, that keeps ABS intact, if that did work. Might be too much to wish for though, haha.


Also, very cool that race cars have manually adjustable ABS, I didn't know that! It makes sense that as your tires heat up, or if you change tire compounds during the race, or if you change your brake bias, you would also want to change ABS settings. I'm actually glad not to have to fiddle with that on track, I feel like I have enough to do already :)
 

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The description from the blog on Sector111 and the behavior posted are definitely not in agreement. Hopefully Shinoo will chime in on his source.
I would say that they are largely in agreement, in my experience. But then again, I'm running the 315/330mm AP Racing BBK, so it's possible that the additional advantage of the size of the brakes makes "pushing through" much for effective than for the stock setup. I dunno :shrug:
 
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