Ice Mode - Anyone fix it yet?

[Chili Red]

The faster I get the more I encounter ICE mode. I think my driving style is part of why I activate it so much (2-3x a lap on most tracks) and continues to increase as I push my braking points forward.

Generally this plays out when Im at high RPM (7500+) and quickly transition from gas to brake. The pedal is extremely hard for 1 to 1.5 seconds and then finally drops. During this hard pedal some braking is happening, but not the full amount. If I wait for a second or after releasing the gas pedal and then press the brake the problem does not occur. This is starting to lead to me not having a whole lot of confidence in my brakes and I normally build in an extra buffer in my braking zones. With more confidence I would push my braking much farther into corners.

If anyone has solved this problem, please let us know..

[MattG]

Wasn't there a theory of this being caused by a loss of vacuum to the brake booster, with check valve replacement being the cure? Your description sure sounds like a lack of vacuum assist.

[MaineLotus]

Pulling the ABS fuse fixes the problem.

[Chili Red]

Originally Posted by MattG

Wasn't there a theory of this being caused by a loss of vacuum to the brake booster, with check valve replacement being the cure? Your description sure sounds like a lack of vacuum assist.

Ive not seem anything that 100% says that fixes the problem.

[jim-clayton]

I used to get the rock hard pedal once and a while. I added a vacuum accumulator up front about 20 track days ago. I haven't had the the hard pedal
since. Can't say for sure that it's a cure.

I have pictures of the install if interested.

[Chili Red]

Originally Posted by jim-clayton

I used to get the rock hard pedal once and a while. I added a vacuum accumulator up front about 20 track days ago. I haven't had the the hard pedal
since. Can't say for sure that it's a cure.

I have pictures of the install if interested.

Yes please post pictures if you have them.. I may just try this if its not to expensive. I can for sure tell if it works or not in one hot lap. I may also try pulling the ABS fuse to see if that helps any.

[jim-clayton]

Originally Posted by Chili Red

Yes please post pictures if you have them.. I may just try this if its not to expensive. I can for sure tell if it works or not in one hot lap. I may also try pulling the ABS fuse to see if that helps any.

Less than $100.00 plus labor. I did it myself in 2 hrs.

[Patricko]

It could be bumpy braking zone confusing the ABS.

If it is that try a suspension adjustment and or change braking point/style.

[jim-clayton]

Since it's repeatable. You can tee-in a temporary vacuum gauge first.

[Jack]

According to the Lotus engineers, ice mode (hard as a brick pedal feel) is NOT caused by a lack of vacuum.

FWIW, Here's the official Lotus explanation of this braking issue:

"The symptoms being described are a result of the Electronic Brake Distribution (EBD) system operating. This system is also referred to as Dynamic Rear Proportioning (DRP) and is, as the name implies an electronic system which, through the ABS control valve block restricts the line pressure to the rear brakes automatically to a pre-programmed algorithm. You can consider it as an electronically controlled proportioning valve which measures parameters like the rate of deceleration and rate of pedal application and uses this data to anticipate a rear wheel lock-up and then reduces the braking effort at the rear wheels as necessary. If the ABS system is left to do this, it can only react to a wheel as it starts to lock and therefore the car can already start to spin before the ABS can start to work. In extreme circumstances, if the driver brakes very suddenly the EBD system can lock off the pressure to the rear wheels completely; what pressure was at the rear brakes as the EBD system engaged remains there and the rear brakes are still working as a result, but further increases in pedal effort will not increase the braking at the rear of the car because the pressure to the rear brakes cannot increase. When this happens the brake pedal goes hard, as it is now pushing against the front callipers and a closed valve only, instead of against the front and rear callipers. The rear callipers are single piston and therefore quite flexible, so they are a major factor in making the brake pedal feel 'soft'. When the valve closes, the brake pedal pressure no longer flexes the rear callipers, hence the increase in pedal hardness. 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. If he increases the pedal effort the front braking effort will increase and the rear effort will remain where it was. If he was to back off the pedal for a fraction of a second, the valve will reopen and the rear brakes will operate as normal again, with the pedal feel going back to normal.

In the case of releasing and re-engaging the pedal the car should not be able to slow any faster than it was with the system engaged unless either 1: the driver triggered the system in the first place by stamping on the pedal too fast or 2: the system triggered because a rear wheel was unloaded when the brakes were applied and would have locked up but is now fully loaded once again and able to sustain a greater braking torque. If the rate of deceleration does improve when the pedal is reapplied then it is telling the driver that he is over braking either in terms of the ultimate ability of the brakes (cause 1 above) or the track condition (cause 2 above) and needs to adjust his driving style to suit. If the system were not fitted or disabled and he continued to drive that way he would be in danger of spinning when applying the brakes.

The suggestion that the system is running out of vacuum is just plain wrong. The system carries an internal reservoir of vacuum sufficient for three full brake applications. As with every servo system ever fitted to a car there is a one way valve which prevents the vacuum being lost when the car is on boost. The only way this reserve can be depleted is if the driver is maintaining boost while applying full brakes, i.e.: left foot braking very badly. In this instance I would argue that depleting the vacuum is probably a good thing as it should provide him with a warning that he is doing something awful to the car and it may reduce the speed of impact when he finally hits something as the brakes fade to nothing!! In normal use the throttle is closed when the brakes are applied, there is therefore no boost and the vacuum is automatically replenished as it is used."

[Chili Red]

Originally Posted by Patricko

It could be bumpy braking zone confusing the ABS.

If it is that try a suspension adjustment and or change braking point/style.

Its not bumps, it happens on smooth track. I have changed my point/style a bit, but it forces me to coast in between the time I lift off the gas and press the brake. As we all know, coasting is not a good thing for your lap times. You should either be on the gas or on the brake.

[Patricko]

Thanks Jack, I think I said that but in the cliff notes version.

I love the last paragraph

[Patricko]

Originally Posted by Chili Red

Its not bumps, it happens on smooth track. I have changed my point/style a bit, but it forces me to coast in between the time I lift off the gas and press the brake. As we all know, coasting is not a good thing for your lap times. You should either be on the gas or on the brake.

It sounds like you may be jumping on the brakes in a on/off manner.

I am just guessing but it is happening too much.

I may be an idea to get a pro driver/coach to drive your car on the same track and see what he thinks.

[jim-clayton]

Originally Posted by Jack

According to the Lotus engineers, ice mode (hard as a brick pedal feel) is NOT a lack of vacuum.

I'm just happy my brick went away.

I almost rear-ended a GT3. Came within inches I'm sure.

(of course it will come back now that I have mentioned it)

[Chili Red]

Originally Posted by Jack

According to the Lotus engineers, ice mode (hard as a brick pedal feel) is NOT a lack of vacuum.

FWIW, Here's the official Lotus explanation of this braking issue:

"The symptoms being described are a result of the Electronic Brake Distribution (EBD) system operating. This system is also referred to as Dynamic Rear Proportioning (DRP) and is, as the name implies an electronic system which, through the ABS control valve block restricts the line pressure to the rear brakes automatically to a pre-programmed algorithm. You can consider it as an electronically controlled proportioning valve which measures parameters like the rate of deceleration and rate of pedal application and uses this data to anticipate a rear wheel lock-up and then reduces the braking effort at the rear wheels as necessary. If the ABS system is left to do this, it can only react to a wheel as it starts to lock and therefore the car can already start to spin before the ABS can start to work. In extreme circumstances, if the driver brakes very suddenly the EBD system can lock off the pressure to the rear wheels completely; what pressure was at the rear brakes as the EBD system engaged remains there and the rear brakes are still working as a result, but further increases in pedal effort will not increase the braking at the rear of the car because the pressure to the rear brakes cannot increase. When this happens the brake pedal goes hard, as it is now pushing against the front callipers and a closed valve only, instead of against the front and rear callipers. The rear callipers are single piston and therefore quite flexible, so they are a major factor in making the brake pedal feel 'soft'. When the valve closes, the brake pedal pressure no longer flexes the rear callipers, hence the increase in pedal hardness. 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. If he increases the pedal effort the front braking effort will increase and the rear effort will remain where it was. If he was to back off the pedal for a fraction of a second, the valve will reopen and the rear brakes will operate as normal again, with the pedal feel going back to normal.

In the case of releasing and re-engaging the pedal the car should not be able to slow any faster than it was with the system engaged unless either 1: the driver triggered the system in the first place by stamping on the pedal too fast or 2: the system triggered because a rear wheel was unloaded when the brakes were applied and would have locked up but is now fully loaded once again and able to sustain a greater braking torque. If the rate of deceleration does improve when the pedal is reapplied then it is telling the driver that he is over braking either in terms of the ultimate ability of the brakes (cause 1 above) or the track condition (cause 2 above) and needs to adjust his driving style to suit. If the system were not fitted or disabled and he continued to drive that way he would be in danger of spinning when applying the brakes.

The suggestion that the system is running out of vacuum is just plain wrong. The system carries an internal reservoir of vacuum sufficient for three full brake applications. As with every servo system ever fitted to a car there is a one way valve which prevents the vacuum being lost when the car is on boost. The only way this reserve can be depleted is if the driver is maintaining boost while applying full brakes, i.e.: left foot braking very badly. In this instance I would argue that depleting the vacuum is probably a good thing as it should provide him with a warning that he is doing something awful to the car and it may reduce the speed of impact when he finally hits something as the brakes fade to nothing!! In normal use the throttle is closed when the brakes are applied, there is therefore no boost and the vacuum is automatically replenished as it is used."

Sounds logical, but I think in my case ice mode is activating so soon in the braking that when the electronic proportioning valve closes the car is not braking very quickly yet. It also seems the hard I press the pedal braking is unaffected until the pedal drops to its normal feel.

Just to clear things up on my braking style. I do not stomp the brakes, I progressively press them hard in the begging of the braking zone and then slowly come off towards the end of the zone to insure proper entry speed into the turn. At the point of apply brakes they are no where near locking up. I know how hard I need to push the brakes to get into ABS and this activates MUCH sooner.

[Patricko]

Originally Posted by Chili Red

Just to clear things up on my braking style. I do not stomp the brakes, I progressively press them hard in the begging of the braking zone and then slowly come off towards the end of the zone to insure proper entry speed into the turn. At the point of apply brakes they are no where near locking up. I know how hard I need to push the brakes to get into ABS and this activates MUCH sooner.

Ok, when was the last time you flushed the fluid?

You may want to go with SRF or something sim.

Did you use the Lotus ABS tool?

I am just trying to think what else it could be.

What pads and rotors are you running?

3 times a lap every lap is crazy. You have a problem of some sort or another

[AZReason]

Thank you Jack for posting this response. I always assumed it was a vacuum issue that caused the hard pedal. This explains why the pedal goes back to normal without letting off the brakes. I have found that what is described does not significantly change my braking distances or lap times on the rare occasion it happens (once or twice per weekend).

On the other hand, I have experienced a phenomenon where the pedal gets soft and the car does not decelerate significantly. I have not experieced it in over a year come to think of it even though my lap times are decreasing. I even had a pro driver experience this phenomenon and had to take the escape road. It seemed to be the worst when I ran on Porterfield street pads.

Unmodified brake system by the way for me.

[Chili Red]

Originally Posted by Patricko

Ok, when was the last time you flushed the fluid?

You may want to go with SRF or something sim.

Did you use the Lotus ABS tool?

I am just trying to think what else it could be.

What pads and rotors are you running?

3 times a lap every lap is crazy. You have a problem of some sort or another

New Motul fluid as of a month ago.

Lotus ABS tool, I have no idea what that is???

I'm running Pagid RS-42's, with Sector111 Ultradisks.

Im pretty sure this is related to my driving style, since i can prevent it from happening by waiting for a second after I get off the throttle to get onto the brakes. That just means that I have to coast for a second loosing a bit of time vs accelerating before braking. Im going to the track again this weekend so Ill play around some more and see what I can do to try and reduce the issue. Maybe a little softer on the initial braking will help a bit.

[Jack]

Originally Posted by Patricko

Thanks Jack, I think I said that but in the cliff notes version.

I love the last paragraph

I knew what you meant -- since I had the unabridged version handy...thought I would publish it in its entirety.

I say change the ABS "pre-programmed algorithm".....

[Jack]

Originally Posted by Chili Red

Lotus ABS tool, I have no idea what that is???

Patrick is referring to the Lotus Scan tool that allows the Lotus technician to activate the abs system while the car is on the lift and flush any air/debris out of the system. A normal brake flush/bleed will not take care of the abs...some suggest doing a flush and then going out on a drive and activating the abs and then doing the bleed all over again...not the best/most thorough way, IMHO. Sometimes there are advantages to having a qualified dealer tech do the service work.