128 hesitating after ~17min

[pixelblue]

Gary, that sounds about right. although I remember at one point when I was considering getting an E36 M3 track car the boys at RRT told me I could get a management system for under $2k so I guess it depends on how custom you need it to be

[Bimmer-Bob]

Are the racing management systems similar to ours, but with much higher thresholds? I guess I'm wondering why you would need to run with one at all? I mean, in wheel-to-wheel racing, where every other team is using one, it's probably a disadvantage not to have one (or may be required by the sanctioning body?). But if you're just tracking/time trialling, and you find it too intrusive, why not just pull it completely? In that case the race module sounds like overkill. Anyway, are these systems federally mandated now? I guess I shouldn't be surprised.

All this computer technology is cool and all, but BMW really should have given us a way to go in and see what's going on - and be able to temporarily defeat everything as needed.

[Hops128i]

Assuming BMW is firstly concerned with public road safety in a car like the 128i, this limp mode is just silly, from how it's been described, how would anyone ever activate it on the public roads without killing themselves first? Is BMW worried I'll overheat totally stock brakes at the track?

[DriveHard]

Originally Posted by DriveHard

I'm still waiting on some more indepth info on this fault logged in the dcs memory.


My car had no other fault accept szl calibration. it was off 1 deg.. must have been from alignment when i put in the camber plates....

basically all this says is a performance reduction happened... doesnt say when or where or for how long ... it does say if nothing else wrong just delete and move on.

I wonder if dsc is recording pressure and brake applications in regards to speed ... in my mind this is the only way the car could think that there could be an iminent possible overheat of the brakes..

Mind you my brakes were 100% all day and showed no signs of any issues whats so ever.

also i guess my brakes reached a possible 1200 degrees according to the prior post for the 5 series notation... Brembos aint so bad after all..LOL

Well after some further research it does infact use a calculation based upon speed accel and decel and quantity and quality of brake application over a given time and it appears to add it all up and then finally reduce throttle above 60mph.
I did see also that this feature is only in civilian versions and not on "m" cars.

I'll be back at limerock in June so I am going to try and clear the dme between runs so it can no longer add up the speed and brake applications and get me thru the third and forth sessions without going into limp. I never got it on the first two sessions of any track day.

Considering what we put the cars thru at the track I see no way to ever induce this on the street so it will have to wait till June.

[TheSt|G]

Any chance you could post up the source material on that? I'd love to read more into it.

[DriveHard]

Originally Posted by TheSt|G

Any chance you could post up the source material on that? I'd love to read more into it.

BEST I CAN DO...SOURCE IS AN ANCIENT CHINEESE SECRET


Fading Brake Support (FBS):
If the driver is unable to make use himself of full vehicle deceleration on account of poor
brake-pad friction coefficients, e.g. due to high thermal loads, he is supported by the FBS
function. The requirement is a high braking pressure with a simultaneously low vehicle
deceleration and high brake-disc temperature.
The FBS function compensates for the brake-force loss through an increase in temperature.
The diminishing braking effect when brakes are hot requires the driver to press the brake
pedal more firmly. This increase in pressure is now assumed by an activation of the
hydraulic pump.
The brake-disc temperature is not measured but rather calculated by means of the following
input variables:
• Wheel speed
• Individual wheel brake pressure
• Ambient temperature
• Number of brake applications over time

AND ALSO

Driving-Performance Reduction (FLR)
The FLR function protects the brakes against overloading in the event of misuse.
If a temperature in excess of 600 ºC is determined, the engine power is reduced to a
defined value (dependent on the type of vehicle) in order to limit the vehicle's accelerating
performance. When the temperature drops below a lower limit (typically 500 ºC), the
reduced engine torque is increased as a function of time on a ramp basis to the maximum
torque again. Driving-performance reduction should only be active from a speed of 60
km/h.
This reduction of the engine torque is stored as a fault (driving performance reduction
active). Should the customer find fault with the lack of engine power, this can be established
by the garage/workshop and explained as brake overloading.


AND ALSO


Brake Temperature Model (BTM)
The BTM function determines by way of a calculation model integrated on a software basis
in the DSC control unit the temperatures of all four brake discs as a function of the input
variables:
• Wheel speed
• Individual wheel brake pressure
• Ambient temperature
If the critical brake-disc temperature is exceeded (t > 600 ºC) at a wheel, DSC functions are
limited as a function of the prevailing driving conditions:
• Locking interventions are reduced to zero for each individual wheel.
• Symmetrical braking torques on the corresponding axle are prohibited.
• The engine torque is limited temporarily via an algorithm for driving performance
reduction.
The restrictions are lifted again when the temperature drops below a further threshold
(t < 500 ºC).

[GaryS]

I got an email from Bimmerworld today:

Our tuner has been trying to find a way to disable the limp home mode he is fairly certain he has found it.

If you would like an EPIC tune I’m sure he would work with you to get it figured out if he did not nail it.

I guess this is the Epic tune:

http://store.bimmerworld.com/epic-mo...eci-p1780.aspx

Contact is Gary Gray <gary@bimmerworld.com>

[GaryS]

Got another email from Bimmerworld about this today. They are basically promising a fix to disable the brake temp limp mode included with an Epic tune.

Epic tune sounds similar to Cobb AP. Pricing is also similar for 135i. I don't know what pricing is for 128i - obviously, 128i's aren't going to get huge HP gains like 135i's.

[DriveHard]

Originally Posted by GaryS

Got another email from Bimmerworld about this today. They are basically promising a fix to disable the brake temp limp mode included with an Epic tune.

Epic tune sounds similar to Cobb AP. Pricing is also similar for 135i. I don't know what pricing is for 128i - obviously, 128i's aren't going to get huge HP gains like 135i's.

us 128 guys.... always the brides maid

Im just hoping with my scanner, i can clear the dsc control unit between runs.. well see.

[DriveHard]

Just a follow up. Next weekend is my limerock day so I'll have everything I need to try to tackle this. Also I found out that the brake light switch can be adjusted out so that dsc sees less brake pedal pressure thus reducing the calculated heat It's a theory need to look into it. Ps one can not remove the brake light switch or u will have all sorts of issues like starting ur car etc

[SkinnyVT]

figured out a better solution, got my e30 back in running condition, Watkins Glen on Monday...mmm grip

[Fireflyer239]

I've had my 128 at Lime Rock running very hard for 4 20-minute sessions in 85-90 degree temps without problems. I hope you can resolve this!

[964junkie]

Originally Posted by SkinnyVT

figured out a better solution, got my e30 back in running condition, Watkins Glen on Monday...mmm grip

This is the right solution, hands down!

But for those of us who still subject ourselves to 1 series torture - DriveHard, what did you end up discovering?

[DriveHard]

Originally Posted by 964junkie

This is the right solution, hands down!

But for those of us who still subject ourselves to 1 series torture - DriveHard, what did you end up discovering?

Funny that u ask.

Spent 2 days at glorious watkins glen over the holiday and I suffered once again with the fault. I would get 4 good laps then limp for a lap or so and then back on it for a few more.

Clearing with a simple code reader does not work as it does not clear DSC control unit faults. I even tried doing a battery disconnect between each session and still no good.

I was supposed to have a real code scanner that reads all control unit faults and is able to clear them but borrowing it fell thru.

I feel the more powerful scanner will do the trick. I'll find out in 2 weeks at NJMP.

More too follow.

P.s. the harder and deeper you drive the more it rears its ugly head. I say this because my buddy who is a better driver took my car out and induced it 8out of 9 laps.

Regards. Alex

[SkinnyVT]

I don't think clearing it will have any effect on how long it takes to activate it again. I would imagine that each session you go out there it essentially starts fresh until you get to whatever the it's preset limit is for "fade". Otherwise you would start off the session still in limp mode.

[964junkie]

Originally Posted by DriveHard

Funny that u ask.

Spent 2 days at glorious watkins glen over the holiday and I suffered once again with the fault. I would get 4 good laps then limp for a lap or so and then back on it for a few more.

Clearing with a simple code reader does not work as it does not clear DSC control unit faults. I even tried doing a battery disconnect between each session and still no good.

I was supposed to have a real code scanner that reads all control unit faults and is able to clear them but borrowing it fell thru.

I feel the more powerful scanner will do the trick. I'll find out in 2 weeks at NJMP.

More too follow.

P.s. the harder and deeper you drive the more it rears its ugly head. I say this because my buddy who is a better driver took my car out and induced it 8out of 9 laps.

Regards. Alex

Thanks Alex. I emailed Gary at Bimmerworld who consulted Epic with regards to this thread, and Gary replied that Epic is "fairly confident they have the problem taken care of" with their Epic tune. I may try this - need to discuss pricing with Gary sometime next week.

At the Glen last Aug, I was able to do a hot lap until the limp mode abruptly arrived, in the vicinity of turn 10, and the car required a cool down lap before allowing me to begin another hot lap. The car almost always made it at or near full bore until ~turn 10 and I was running fairly consistently in the 2:22s with the turn 10 limp mode.

[DriveHard]

Originally Posted by 964junkie

Thanks Alex. I emailed Gary at Bimmerworld who consulted Epic with regards to this thread, and Gary replied that Epic is "fairly confident they have the problem taken care of" with their Epic tune. I may try this - need to discuss pricing with Gary sometime next week.

At the Glen last Aug, I was able to do a hot lap until the limp mode abruptly arrived, in the vicinity of turn 10, and the car required a cool down lap before allowing me to begin another hot lap. The car almost always made it at or near full bore until ~turn 10 and I was running fairly consistently in the 2:22s with the turn 10 limp mode.

964. That's good news. I would love to know outcome and price.

Damn. 2.22. Best I got was 2.27. I'm sure I could have gone faster but it was my first time there and I had to be mentally prepped for the amount of Armco at the glen.

How is ur car prepped?

Regards

[SkinnyVT]

I sent a note to Active Autowerke and got the following response:

"I am sorry but we do not have this available."

Nice to know there is some interest in solving an issue that the community is experiencing...

[964junkie]

I spoke directly with Randy Mueller at Epic Motorsports, who sounded very knowledgeable and willing to help. But, the Epic tune is $700 and there is no guarantee the issue will be resolved. Randy would work with me to tweak the software based on my feedback, but I have no desire to invest $700 into an experiment and risk wasting further laps in limp mode.

As for an additional data point which I mentioned to Randy: I did my own experiment - I achieved the same "power reduction" mode symptoms purely through throttle and high rpm application - with little to no braking - on the street during a hot day. It took about 15-20 miles driving like this for the car to get into the limp mode. Hope this helps.

Alex - after checking the AIM Solo data I realized I was doing 2:23s (not :22s). As for the setup, I had bilstein PSS9s, dinan camber plates, an eibach 28mm front sway bar, performance alignment, square 235/40 18 dunlop direzza z1 star spec tires, hawk hp plus brake pads, motul 600 brake fluid, and 10-15 days at the Glen prior.

My days of trying to fight the 128i automatic are over. I've conceded. Best of luck to everyone. Time to look into a more appropriate track car, like an E36 or E46 M3, or an E30 like SkinnyVT.

[Hops128i]

Originally Posted by 964junkie

As for an additional data point which I mentioned to Randy: I did my own experiment - I achieved the same "power reduction" mode symptoms purely through throttle and high rpm application - with little to no braking - on the street during a hot day. It took about 15-20 miles driving like this for the car to get into the limp mode. Hope this helps.

wow, so you were able to get brake temperature model to 'think' the brakes were hot, when they really were not! I wonder too if this brake limp mode is also safe guard against a 'stuck' throttle, like what happened with toyota.

Well, this whole thread has really given me pause doing any track friendly mods. It's a real bummer, because I've been excited about eventually doing HPDE's and more after I get tired of just doing autocross. I guess i can hope as more used 128i's see the track, someone out there will find a solution.

[DriveHard]

Just an update..

Im still working on it.. ill have some info in fact tonight.. hoping to at least be able to have a "track-only" work around... I suspect that once off track or after the days runs, one will have to clear fault memories...maybe reinstall some components..

I was at NJMP last weekend, and did pretty good.. I borrowed a lap top that mimiced a BMW diagnostic tool ( GT1) This allowed me to clear DSC faults in between each session. ( as opposed to cheap scan tools that dont see "control units" This enabled me to go further into the runs without getting into Limp. It did happen but at least 3/4's of the session was Limp free"

Oddly enough i saw something else.. Before I left my house I had cleared all faults etc.. as i was playing around with the laptop..

Prior to Getting to the track, I always was in the practice of doing some decent braking to sudo re-bed the pads a little prior to the days events.. I must of done 8 good stops as usual and all was well... I had some time after registration so I wanted to make 100% sure that all faults were clear.. well guess what.. I saw the fault but it never put me into Limp.. it was up to "event # 40 " meaning that DCS counted something 40 times..... this must be used by the system to actually add up the events to finally put me into Limp.. writing this, i never looked at the counter inbetween sessions ( slapping head) I would have know how many it actually takes to induce it ( slapping head again) Oh well...

As soon a s i know something ill post back..

p.s Ran a 1:22.4 at Lightning !!!

[TheSt|G]

Thanks for keeping up with this. I've been looking forward to getting her out onto the track, and this limping has made me a bit wary.