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View Full Version : Left-Foot Braking Causing "Limp Mode?"



Mr. Man
03-19-2013, 12:25 PM
I had this happen to me a few times. Anyone else had this happen?

Mr. Man
03-19-2013, 12:32 PM
Well after doing some reading I see that the sensors are set up to do that. But why is that? Having full boost out of a corner is beneficial for a laggy car like our abarth but it seems that won't be possible

shagghie
03-19-2013, 12:38 PM
Well after doing some reading I see that the sensors are set up to do that. But why is that? Having full boost out of a corner is beneficial for a laggy car like our abarth but it seems that won't be possible

Does limp mode kick in right as you are hoping for power? Meaning... does it offset the suspension when you aren't expecting it and feel unsafe? There is another thread on here in the Racing section...someone else is successfully using LFB at autocross... wondering if turning traction control off all the way allows for more LFB before limp mode engages? I forget the trick...

redred
03-19-2013, 12:38 PM
Does it do this with the ESC fully off too?

BigDaddySRT
03-19-2013, 12:41 PM
Well after doing some reading I see that the sensors are set up to do that. But why is that? Having full boost out of a corner is beneficial for a laggy car like our abarth but it seems that won't be possible

It's a built in Safety Feature for the Ride By Wire System.

BigDaddySRT
03-19-2013, 12:42 PM
Does it do this with the ESC fully off too?

Yes.

shagghie
03-19-2013, 12:47 PM
Hell I'll probably be faster around the cones in limp-mode than under boost anyways... still going to find some road time somewhere to practice this before the next event.

trevc
03-19-2013, 01:38 PM
Practice your handbrake turns as well!

Hell I'll probably be faster around the cones in limp-mode than under boost anyways... still going to find some road time somewhere to practice this before the next event.

Shagnwrx
03-19-2013, 01:49 PM
You have to hold the brake for 2 seconds to engage the Brake/Throttle Override. So, if you can keep your left-foot braking below two seconds each time, you should be okay.

Jjm4life
03-19-2013, 02:40 PM
It's a built in Safety Feature for the Ride By Wire System.

This. Sucks too since its an effective driving technique.

BigDaddySRT
03-19-2013, 03:08 PM
This. Sucks too since its an effective driving technique.

Not for 99.99999% of the people driving their ABARTH on the Public Roads.

Jjm4life
03-19-2013, 03:18 PM
Not for 99.99999% of the people driving their ABARTH on the Public Roads.

Oh I know. Just ruins the fun for the rest of us

But yea... Ridiculous weight bias, short wheelbase. Makes sense why it goes into limp mode

FiatCares
03-19-2013, 04:09 PM
Does it do this with the ESC fully off too?

most likely.

FiatCares
03-19-2013, 04:10 PM
I had this happen to me a few times. Anyone else had this happen?

Really? I have never heard of that before... and Ive always used my right foot for accelerating, my left foot for breaking... yeah.. I am one of those people lol. However, I do not ride the brake with my left blinker on going up or down hills :)

Saxonite
03-19-2013, 08:11 PM
I think it required by law that all cars have the brake throttle override as of 2013 as a response the the "accidental acceleration" epsiodes in recent years. Does the power come back on fairly soon after releasing the brake? I can try and see if the same thing happens to my car when I head home from work. I have a first run 2012. Is your's a 2013? Sadly that could be the reason for it happening.

HF Stinger
03-19-2013, 08:25 PM
This has been a 'safety' feature for a decade if not longer. We found out about this when the ~2000 Audi S4's were starting to hit the track. All of us ol' school nose-heavy Audi guys were avid left foot breaker's but drive-by-wire put and end to that. It's very upsetting to experience this mid corner on a fast road track...

Guest
03-19-2013, 09:40 PM
Been a few threads on this issue. When the accelerator and the brake are depressed simultaneously the car goes into limp mode, safety feature that sadly cant be switched off.

msjulie33
03-19-2013, 10:58 PM
Been a few threads on this issue. When the accelerator and the brake are depressed simultaneously the car goes into limp mode, safety feature that sadly cant be switched off.


Yup my 2001 Audi did this and yeah, it did mess up auto-x until I realized it really was a full 2 seconds of brake and gas together to get it to trigger... so brake less :)

Fiat500USA
03-20-2013, 12:49 AM
Here are a couple of threads on this:

Loss of throttle response (http://www.fiat500usaforum.com/showthread.php?7374-Loss-of-throttle-response)

Strange Thing Happened Today (http://www.fiat500usaforum.com/showthread.php?8272-Strange-Thing-Happened-Today)

FiatCares
03-20-2013, 12:36 PM
I think it required by law that all cars have the brake throttle override as of 2013 as a response the the "accidental acceleration" epsiodes in recent years. Does the power come back on fairly soon after releasing the brake? I can try and see if the same thing happens to my car when I head home from work. I have a first run 2012. Is your's a 2013? Sadly that could be the reason for it happening.

this is true. If the accelerator is pressed and the left foot rests on the brake enough for it to register, a fault code will be triggered. Ignition cycles ON/OFF should reset it and power should be restored.

Pinecone
03-24-2013, 05:04 AM
I don't left foot brake and have had this occur.

It seems you have to shut off the engine and restart to clear the limp mode. :(

BMW got this setup in the first DBW 7 series in 2001. But the E46 M3 in the same time frame did not get this.

MAZ
03-29-2013, 10:24 AM
It's a built in Safety Feature
^agreed.
Same reason most cars leave the factory with massive understeer, b/c it is 'safer' for the 'general public'

Use the E Brake!

trevc
03-29-2013, 10:40 AM
I would love to get access to a witech system to see exactly what things can be switched off/on/tweaked in our cars. Unfortunately they appear to be expensive/require a subscription and costly training.

BigDaddySRT
04-03-2013, 10:07 PM
Are you guys turning the Hill Assist OFF?

Mr. Man
04-04-2013, 08:25 AM
I've left mine on because I became used to driving with it on before I discovered what was going on. I wouldn't want to forget early in the morning and bump into one of those jerks that creeps too closely

Racerflash
04-04-2013, 12:49 PM
Are you guys turning the Hill Assist OFF?

Does Hill Assist have anything to do with the left foot braking problems?

BigDaddySRT
04-05-2013, 07:52 AM
Does Hill Assist have anything to do with the left foot braking problems?

Well... I am wondering for those trying to apply the brake and throttle at the same time if they have the Hill Assist ON or OFF.



I have no urge to try it in my ABARTH and see if the Hill Assist is what's causing the issue.

KKaWing
04-11-2013, 11:56 PM
I'll just leave this here. I found it as I was killing time and looking up Abarth videos on youtube.
Seems like it is from a "coding" outfit.



http://www.youtube.com/watch?v=2-ZV9lhYPDI

sczuylevch13
07-02-2014, 06:14 PM
things about this topic, #1: at the abarth driving experience our instructor was totally left foot breaking on the autocross when he was taking guests around! and #2; about 2 weekends ago i was testing my gravel skills out and i was LFB and E-brake sliding to see what I liked better, and no limp mode. perhaps me nor ricky from team shake and bake didnt have both pedals depressed for over 2 seconds. both cars were 2013s i will say it doesnt take much LFB to get the back out on gravel, but the e brake seemed to work better for me anyway. in my old omni glh LFB was the ticket tho! i could do things in that car on snow that i never could have imagined a front wheel drive car doing.

CCR#5
09-30-2014, 10:14 AM
I would love to get access to a witech system to see exactly what things can be switched off/on/tweaked in our cars. Unfortunately they appear to be expensive/require a subscription and costly training.
not much that can be done, witech is mainly for collecting diag info and testing module communications. On the fiats in particular all changes are locked out to corp engineers access only.

On the OPs original question it is indeed a safety item that was mandated by NHTSA after the Toyota unintended accel. dibaucle. Anytime the ecu sees both excessive throttle and brake, it will disable/limit throttle giving the brake priority and throw a code if it deems it excessive in amount or frequency. Heel toeing will also throw this code if done repeatedly in a short time period. I can't remember the exact count/% trigger, but the likelihood of throwing the code is increased dramatically with the use of a piggyback, well atleast the 2 I've tested thus far. That being said its easy to clear. You can either cycle the key a whole bunch of times or reset the ecu/disco the battery.

Crazy Otto
10-01-2014, 08:19 PM
yep.....heel and toe will trigger, sometimes randomly....absolutely sucks for a car that's aimed at enthusiasts.

Crossfirecat
10-01-2014, 08:20 PM
yep.....heel and toe will trigger, sometimes randomly....absolutely sucks for a car that's aimed at enthusiasts.

Yup! We can all thank Toyota for this!

jguerdat
10-02-2014, 07:12 AM
Not sure it's Toyota's fault. Audi had unintended acceleration issues in the '80s. I can't believe 100hp engines can overpower almost ANY brakes being held with full pressure - just doesn't happen. And now Toyota has another claim of such issues. Maybe people need to actually pay attention to their driving.