Ice mode does more harm than good, with video example - LotusTalk - The Lotus Cars Community
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post #1 of 35 (permalink) Old 04-21-2016, 04:32 PM Thread Starter
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Ice mode does more harm than good, with video example

Someone dumped their radiator full of fluid in the hardest braking zone of my favorite track, and I was the first person to "discover" this situation. I pushed my brakes only to find a rock-hard pedal and hardly any braking force, I figured huh, that's odd, I don't usually get ice mode here, but I did the standard thing, let go of the brakes, and try again, but to no avail, a wheel or two must have still been sliding, so I stayed in ice mode and couldn't bleed off much speed. I had to take a sharp turn way faster than possible to make it, and aim the car into a grassy field away from tire walls. Fun.

Other cars which hit the slick spot got wiggly and some got sideways, but at least their brakes worked. Lame.

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post #2 of 35 (permalink) Old 04-21-2016, 04:44 PM
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Damn that sucks but hey it could have been alooot worse. Have not had the ice mode experience yet. Still apprehensive about it. I flush all brakes and clutch before every event. I do brake at hard at 3 cone though and carry speed through corner

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post #3 of 35 (permalink) Old 04-21-2016, 04:58 PM
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Did you add a vacuum tank to your brake booster ? Helped my ice mode.

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post #4 of 35 (permalink) Old 04-21-2016, 05:18 PM
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Hey Jim please elaporate at your convenience. What is it? I get it is probabably an accumulator tank but volume has an effect. Thanks

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post #5 of 35 (permalink) Old 04-21-2016, 11:47 PM
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That could have been a lot worse. You had a ton of runoff and it was on grass not gravel. Count those lucky stars!

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post #6 of 35 (permalink) Old 04-22-2016, 12:49 AM
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On cold wet days, i can get ice mode on a straight line while driving under normal street speed conditions.
The system is simply set up wrongly by Lotus.
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post #7 of 35 (permalink) Old 04-22-2016, 01:58 AM
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This isn't 'ice mode' - it's simply ABS. Coolant is crazy slick and coated the tires. The idea behind ABS is to allow the tires to keep rotating or else steering inputs are useless. You see, you were able to still steer because ABS was doing its job. There's just not going to be any stopping power at all with glycol on your tires


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post #8 of 35 (permalink) Old 04-23-2016, 06:28 AM Thread Starter
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No, I'm sure it was ice mode. I hit ABS all the time on track, even on full slicks. It has a very specific pedal feel. ABS in this car is very high frequency and you can feel a buzzing, but the pedal feel is fairly normal. Ice mode makes the pedal feel rock hard, and it doesn't depress as far - it's like there's something between the pedal and the floor.

I know roughly how much grip I had based on how hard I was able to turn, and it was way more than my brakes were letting me use. There's another turn on that track where the rear inside tire gets real light, and I can hit ice mode 100% of the time, and actually have to be careful there every lap.

It's a bad system unless you're driving on ice I've driven many cars at the track, and let me tell you, the Elise is the only car that I've encountered so far with this strange braking behavior. I like ABS enough that I'm not willing to sacrifice it by pulling the fuse, so I just deal with the ice mode.
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post #9 of 35 (permalink) Old 04-23-2016, 07:04 AM
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Originally Posted by marcinr View Post
There's another turn on that track where the rear inside tire gets real light, and I can hit ice mode 100% of the time, and actually have to be careful there every lap.
Which turn? When I've suffered Ice Mode, it was usually hard braking into 10 (at Thunderhill).

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post #10 of 35 (permalink) Old 04-23-2016, 07:37 AM Thread Starter
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Yeah, T10 can do it, especially when cresting the small hill just before the turn-in zone. I get it almost all the time braking up into T5 over the crow's nest, if I've got any steering input while braking, so I have to make sure to brake there absolutely straight, then turn in. Normally, I trail brake into turns as much as possible.
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post #11 of 35 (permalink) Old 04-23-2016, 07:51 AM
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Hah! Yep, T5 as well. That's my 2nd most likely ice mode corner. If nothing else it's useful (or reassuring?) to know the problem is consistent/repeatable. I trailbrake both 5 and 10, but ice mode in 10 kicks in during straight line braking... Way before turn in. At any rate, now I just anticipate/manage the issue. I too would rather not give up ABS, which I find pretty unobtrusive and helpful in this car.
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post #12 of 35 (permalink) Old 04-23-2016, 09:31 AM
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I was having all sorts of braking problems on a bumpy track, I have none now after the following:

Disable ABS with fuse
CL RC6 pads all around
Stainless lines all around (when I only had in the rear I think this was causing trouble).
Pull vacuum lines all apart and make sure they are plugged in right front and rear of car and check valves work.

Now the brakes work awesome all the time and they are pretty modular so I don't typically have trouble with brakes locking up.
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post #13 of 35 (permalink) Old 04-23-2016, 12:23 PM Thread Starter
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It's easy to avoid T10 ice mode at Thunderhill. The problem is that there's a little hill just before you see the T10 turn-in point, and when you're cresting that hill with full brakes, the car gets light and some wheels start to slip under braking, and ice-mode kicks in. Brake a tiny bit earlier, and as hard as you can on the upside of that little hill, then ease off a little as you crest, and back to full brakes. I've been doing that forever and I haven't experienced ice mode there since. As for T5, meh, it's a throw-away turn, so a little sub-optimal entrance is no big deal.
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post #14 of 35 (permalink) Old 04-24-2016, 08:28 AM
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Originally Posted by cyow5 View Post
This isn't 'ice mode' - it's simply ABS.
That was my 1st thought. I think our ABS cycling interval is very long (2 sec ?) and always assumed it was a product of the GM/Opel sourced system.

When I've encountered either pure ABS or "ice mode", I have to let off the brakes for a full one-one-thousand count before it resets.

In the video, it looks about 1 sec from braking zone to your fully committed to the off.

Hey, at least it's better than 1st gen ABS of the early 90's. I remember experiencing virtually useless 2 channel systems, where you could really feel the ABS pump @ ~10 hz.

Glad you had grass!

OK re-reading about ice-mode, it's possible I've *never* experienced pure ABS, so all my pucker moments have been this... yeah not fun.

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post #15 of 35 (permalink) Old 04-24-2016, 11:56 AM
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If I'm not mistaken, the ice mode tell tale is that the pedal gets unusually stiff. I've not experienced the hard pedal yet myself, but definitely have used the ABS functionality. I'm prepared to pump the brakes in that moment, we'll see if I remember!

Pretty good write up on this "feature": Sector111's Tasty Innovations Blog: Lotus 'Ice Mode' Explanation

One note about the Sector111 write up vs what I read from drivers... Sector111 indicates that you can still just press on the brake hard and it should stop, whereas I read many drivers describe the brakes nearly quit working.

Of course, on track when you are trying to drive the car at or near 100%, ANY braking reduction is a potential problem. Coming in at near max speed though a pool of antifreeze just before a tight turn is going to put you in a pickle, ice mode or not.

Last edited by Parko; 04-24-2016 at 12:05 PM.
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post #16 of 35 (permalink) Old 04-24-2016, 06:12 PM
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Hi marcinr, I 'm sorry to hear you had this happen, scary place for it! I'm glad all is okay. I too have had ice mode into turn 10 at Thunderhill, but fortunately without any coolant to make the ride more "entertaining" haha. Even that was scary so I can only imagine...

The interesting thing here is that my experience was in an '05 Elise but I have since switched to an '07 Exige S and I do not have that problem any more. I have only hit ice mode once, very briefly, in the 'S and that was under hard braking on some sandy gravel someone had pulled onto the inside of a corner at Buttonwillow. I wonder if the design, or even the factory settings (?) are different on some cars because my Elise would go into ICE mode pretty regularly (especially at autocrosses, during the first couple of runs when the course wasn't clean yet).

For those of you that haven't had it, it is very different than the ABS feel, as described, like a very hard, ineffective pedal with a different pulsing feel than the ABS, very unsettling (especially since it usually happens when you need it most, and it usually catches you by surprise unless you are doing the same thing again like at a track or an autocross).

The other interesting thing is that when it did happen in my 'S, it went from ABS pulsing, into ICE mode, then back to normal ABS mode pretty smoothly so I had a lot less of that panicked screaming sound in the car, haha. Makes me wonder if there is a way to transfer some sort of programming from a car that works well to one that doesn't? I am not a tech guy so that may not be possible.

Any thoughts on this out there? It would be great to be able to cure this problem on those overly sensitive cars without having to disable the ABS...
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post #17 of 35 (permalink) Old 04-24-2016, 06:31 PM
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And now that I have read the Sector 111 link I have to agree with the comment that the article there does not describe what it actually feels like or how the car seems to behave. There is DEFINITELY way less braking ability in the front of the car, and it does not come back in the front with more pressure. I am 6'-3'' 200 pounds and with full force on the pedal almost no front braking remains even after the gravel/sand/whatever has been passed over (if you keep your foot on the brakes). And the pulsing is slower than ABS mode. It does not behave like it is just the rears being locked out of the circuit, more like all four brakes are locked at a much lower level of braking ability than in ABS mode.

Pumping quickly does remove it, but it is very hard for your brain to go there (or at least mine) with the sudden change in your braking ability when you need it most and are not expecting it.
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post #18 of 35 (permalink) Old 04-25-2016, 04:03 AM
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No, I'm sure it was ice mode. I hit ABS all the time on track, even on full slicks. It has a very specific pedal feel. ABS in this car is very high frequency and you can feel a buzzing, but the pedal feel is fairly normal. Ice mode makes the pedal feel rock hard, and it doesn't depress as far - it's like there's something between the pedal and the floor.

I know roughly how much grip I had based on how hard I was able to turn, and it was way more than my brakes were letting me use. There's another turn on that track where the rear inside tire gets real light, and I can hit ice mode 100% of the time, and actually have to be careful there every lap.

It's a bad system unless you're driving on ice I've driven many cars at the track, and let me tell you, the Elise is the only car that I've encountered so far with this strange braking behavior. I like ABS enough that I'm not willing to sacrifice it by pulling the fuse, so I just deal with the ice mode.

ABS does not just control tire slip to a certain amount - it also has to balance that while controlling to a specific rate of decel as well. So if your target slip is 10% but the tire is currently at 2% and got there very quickly then ABS may still kick in and pretty aggressively. In that case, it kicks in very hard because it knows that if it doesn't then you'll exceed that 10% target in no time.

To make matters worse, you mention tires that have hugely different grip profiles than factory, and it wouldn't be unreasonable to assume that your wheels, pads, and rotors are all different, too. ABS control is already a very unstable system, so surely it can't make that any better when you change all the physical components and then ask it to still operate perfectly.

So to reiterate:

1) ABS control is a very, very finicky procedure (think of trying to balance a broom upright in your palm. In a hurricane. Blindfolded)

2) You've changed at least two major components - road surface and tires - and never told the ABS controller how to deal with those changes.

3) ABS does not control to a slip amount only. It also has a slip rate target and will pick the one of those two that is worse. This will be exacerbated by bitey pads or lower inertia wheels/tires/brakes.

4) The ABS controller only has wheelspeed sensors as inputs, so it cannot know what is going on around it other than what can be gleaned by those sensors and the brake pressure.

There is also heavy legal pressure to intervene too much rather than not enough. Put yourself in those shoes and you'll see that this "Ice Mode" is a natural consequence of these points.
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post #19 of 35 (permalink) Old 04-25-2016, 06:01 AM Thread Starter
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I'm not so sure if this is a natural consequence of the requirements which you mention, because, other cars' brake controllers seem to handle this far more gracefully. I wasn't the only one to hit this slick, for instance, and I've also engaged ABS on quite a few different cars on the track, only the Elise seems to have this bizarre behavior.

The track guys, and particularly the auto-crossers know well about whatever "ice mode" is, and it's a design problem in the braking system for those particular uses. I don't know if you've ever hit the ice mode in your car, but it's positively frightening, even if you hit it on the street, because braking force is severely limited. My guess is they've done this to prevent creating a yaw moment on the car if one side is on ice, but it seems to engage way too aggressively and stays engaged until releasing the brakes.
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post #20 of 35 (permalink) Old 04-25-2016, 06:36 AM
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I'm not so sure if this is a natural consequence of the requirements which you mention, because, other cars' brake controllers seem to handle this far more gracefully. I wasn't the only one to hit this slick, for instance, and I've also engaged ABS on quite a few different cars on the track, only the Elise seems to have this bizarre behavior.

The track guys, and particularly the auto-crossers know well about whatever "ice mode" is, and it's a design problem in the braking system for those particular uses. I don't know if you've ever hit the ice mode in your car, but it's positively frightening, even if you hit it on the street, because braking force is severely limited. My guess is they've done this to prevent creating a yaw moment on the car if one side is on ice, but it seems to engage way too aggressively and stays engaged until releasing the brakes.
I have hit it a few times, especially when I had heat-cycled and cold R888s and I have also professionally calibrated ABS systems for several race teams, so I have an extremely good understanding of how the theories work.

The Lotus manual even states that the ABS is intentionally programmed to allow more slip than most, but this is why then it has to try extra hard to make sure this slip is not exceeded since there is less margin for error. I am not saying the calibration could not be better, but it is at a reasonable level for production calibrations that have to be pushed through fairly quickly. Especially since I would recalibrate a car if it had a pad change and nothing else. The tighter your tolerances are, the more important it is to model the entire system accurately. One car, for example, ran best with a specific combination of master cylinder and brake pads and changing the pads from that made it very hard to get the ABS just right for the driver.

With all that being said, I did some reading in the service manual and found some interesting stuff. My first thought about why the pedal stays dead until you repump it is because there is no way to increase the pressure other than hitting the pedal anew. Actually though, the Lotus unit does incorporate an electric pump that raises the pressure when in ABS. It is possible that this motor is underperforming or underspec'd and cannot provide enough pressure fast enough when the full system has been bled but it works fine for moderate interventions. I don't know the specifics of this system well enough to speculate further than that though.

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