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Serious braking issue in wet conditions

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Old 02-28-2014, 02:46 PM   #1
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Default Serious braking issue in wet conditions

I purchased a 2014 Q5 in September. Over Christmas I drove from Canada to Florida and encountered some serious rain throughout Georgia. After driving for a while and having to apply the brakes suddenly, while keeping constant pressure on the pedal, the brakes released and then slammed on again themselves. At first i thought maybe this was the computer in the rain and i was able to replicate it several times. It wasn't due to pad purging because of the replication.

Fast forward a month later back in Canada driving to the ski hill, and the same this happens slowing from highway speed, this time its snowing and cold. the brakes release and slam on, jerking around the people in my car.

Has anyone encountered this? Audi couldn't diagnose it without replicating it and we haven't had wet conditions to test here. They did seem concerned. My fear is having to brake suddenly and the brakes releasing and slamming me into another vehicle...

Last edited by 14Q5; 03-01-2014 at 03:54 PM.
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Old 02-28-2014, 06:46 PM   #2
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could have been abrupt downshift of the transmission?
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Old 02-28-2014, 07:30 PM   #3
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Sounds like ABS kicking in. Steve
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Old 02-28-2014, 07:38 PM   #4
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It's not a downshift.

It feels completely different than abs. It doesn't make the sound of the abs either. It makes a loud bang sound. Do you think the abs would completely release the brakes for a second then reapply them all at once? this would seem like a serious safety issue no? I thought it was abs until the two car guys with me thought I was trying to make their heads slam off the dash on purpose.
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Old 03-01-2014, 11:56 AM   #5
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Originally Posted by 14Q5 View Post
It's not a downshift.

It feels completely different than abs. It doesn't make the sound of the abs either. It makes a loud bang sound. Do you think the abs would completely release the brakes for a second then reapply them all at once? this would seem like a serious safety issue no? I thought it was abs until the two car guys with me thought I was trying to make their heads slam off the dash on purpose.
I would think it is a downshift - were you in Auto mode with the transmission. This is not how ABS works. I have had my brakes be slow to respond after the car wash but this is a gradual thing not: on - off - sudden on again.

This is a safety issue. Someone who is competent needs to look at this issue for you
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Old 03-01-2014, 12:32 PM   #6
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... constant pressure on the peddle, the brakes released...

I think I have identified the problem.

Try applying constant pressure on the brake pedal rather than the peddle. The peddle is not there to reduce any movement in the car. Peddle is used when you try and sell the car.

Do you want to try the pedal and see whether the problem persist?




























... Sorry, slow afternoon with rain here in SoCal.

.

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Old 03-01-2014, 01:15 PM   #7
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The first time I had an ABS kick in (not on the Audi) was a "WTF?!" moment on wet concrete that was totally unexpected. Even if you are sure this is not the usual ABS action, there's nothing else (AFAIK) that can actuate the brakes except the ABS system, and it sounds like yours gave one hard pulse to the brakes, for whatever reason.

I would strongly suggest filing a complaint on the NHTSA.GOV web site, and letting Audi-US know that you are doing so. That's the only way to ensure, first, that there is a complaint on the record about your particular vehicle, and second, that there is reason to question the brake system on the entire model run.

The process is slow--but everyone gets motivated when there's an NHTSA complaint on file. Maybe it is somehow pilot error, i.e. if you clipped both pedals at once for a moment. Let them be motivated to find out.
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Old 03-01-2014, 02:59 PM   #8
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Default Probably the auto-dry bake/EBA systems...

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Originally Posted by 14Q5 View Post
I purchased a 2014 Q5 in September. Over Christmas I drove from Canada to Florida and encountered some serious rain throughout Georgia. After driving for a while and having to apply the brakes suddenly, while keeping constant pressure on the peddle, the brakes released and then slammed on again themselves. At first i thought maybe this was the computer in the rain and i was able to replicate it several times. It wasn't due to pad purging because of the replication.

Fast forward a month later back in Canada driving to the ski hill, and the same this happens slowing from highway speed, this time its snowing and cold. the brakes release and slam on, jerking around the people in my car.

Has anyone encountered this? Audi couldn't diagnose it without replicating it and we haven't had wet conditions to test here. They did seem concerned. My fear is having to brake suddenly and the brakes releasing and slamming me into another vehicle...
may be the issue

"The mid-size five-passenger Audi Q5 luxury crossover and the Audi Q7 seven-passenger full-size luxury SUV both have auto-dry brakes as part of the braking system. In wet conditions, the disc wiping system gently pulses brakes to help remove water buildup. The most effective braking results from keeping the discs as dry as possible. In addition, the brake system is able to detect the driverís attempt at full braking and can apply full stopping power when required. The advantage of this is that braking distance is significantly reduced."

Also if you hit the brakes hard, the the Electronic Brake Assist takes over automatically....

"By interpreting the speed and force with which the brake pedal is pushed, the system detects if the driver is trying to execute an emergency stop, and if the brake pedal is not fully applied, the system overrides and fully applies the brakes until the Anti-lock Braking System (ABS) takes over to stop the wheels locking up."

Some day take your car out on a dry road and at about 35 mph wack the brake pedal hard and fast, and you will be surprised at the feeling of the car trying to bury itself into the road and stop. It's a great feeling!

Bottom line, one, or both of the above systems may be suspect.....
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Old 03-01-2014, 03:54 PM   #9
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may be the issue

"The mid-size five-passenger Audi Q5 luxury crossover and the Audi Q7 seven-passenger full-size luxury SUV both have auto-dry brakes as part of the braking system. In wet conditions, the disc wiping system gently pulses brakes to help remove water buildup. The most effective braking results from keeping the discs as dry as possible. In addition, the brake system is able to detect the driverís attempt at full braking and can apply full stopping power when required. The advantage of this is that braking distance is significantly reduced."

Also if you hit the brakes hard, the the Electronic Brake Assist takes over automatically....

"By interpreting the speed and force with which the brake pedal is pushed, the system detects if the driver is trying to execute an emergency stop, and if the brake pedal is not fully applied, the system overrides and fully applies the brakes until the Anti-lock Braking System (ABS) takes over to stop the wheels locking up."

Some day take your car out on a dry road and at about 35 mph wack the brake pedal hard and fast, and you will be surprised at the feeling of the car trying to bury itself into the road and stop. It's a great feeling!

Bottom line, one, or both of the above systems may be suspect.....
This could definitely be it. I had an issue on my tiguan that if i didnt purge the disc the brakes would slip.
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At first i thought maybe this was the computer in the rain and i was able to replicate it several times. It wasn't due to pad purging because of the replication.
I think maybe its the emergency eba you referred too. However in these conditions it definitely isn't reducing my stopping distance. I will investigate your theory further. Thanks!!

Last edited by 14Q5; 03-20-2015 at 06:17 PM.
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Old 03-02-2014, 03:50 AM   #10
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Also watch our for the cruise control hitting the brakes "for you". I never even realized it would do that until pulling a trailer downhill at night and noticed the brake lights coming on by themselves.

Set the cruise for something like 50, then floor it up to 80 and let up. The brakes will self-apply rather firmly. I don't like it.
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Old 03-02-2014, 04:36 AM   #11
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Here's another hypothesis. If you were traveling in serious rain, your tires may have been hydroplaning. Your ABS probably kicked in. It felt like the car released the brakes due to the hydroplaning. Once you were out of the deeper water, your tires regained traction with the road and you got some braking. I'm thinking that this is why you think the brakes released and then re-grabbed. My bet is that your car is just fine. The answer might be to steer around deeper water and/or slow down in these conditions.
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Old 03-02-2014, 05:12 AM   #12
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Also watch our for the cruise control hitting the brakes "for you".
Cruise control can also apply the accelerator if you're slowing down while hydroplaning with alarming consequences. We shouldn't use cruise control in the wet. Steve
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Old 03-03-2014, 04:12 AM   #13
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Cruise control can also apply the accelerator if you're slowing down while hydroplaning with alarming consequences. We shouldn't use cruise control in the wet. Steve
Yes, perhaps a little off topic, but also true on ice.
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Old 03-16-2015, 04:56 AM   #14
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Alright, has happened recently again, including on the weekend.

Wetish conditions, braking on a off ramp and the person infront of me jams their brakes. I brake harder and the brakes released and jam, sending my Q5 into a nose dive. Previously happened in hard wet braking.

My thoughts are the wet conditions cause the brake pads to slip (had this issue on my Tiguan) and purging the brakes would clean off the water. In 2013, VW even started advertising this 'new' auto pulse braking feature when the wipers were on, obviously because it was a known issue. I think in the Audi case, the computer sees the brakes are applied, but the brakes are slipping or not slowing at the calculated speed causing the computer to pulse hard. Nearly rear-ended someone because of it. Car nosedives hard.

Its been over a year, maybe someone has encountered this now?
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Old 03-16-2015, 08:31 AM   #15
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Coming from the days when disc brakes were a high-end oddity and DRUMS were the norm, I will say that disc brakes "don't" slip in the wet. Compared to the way that drum brakes would and sometimes did stop you on the far side of an intersection after going through a puddle, I would be very curious to actually see an explanation for disc brakes showing any significant "slippage", i.e. for more than one wheel revolution.
But I'll accept anything as possible.

If you are in the US, please contact the national Highway Transportation & Safety Administration at nhtsa.gov and FILE A COMPLAINT. If they receive multiple reports, they can order an investigation and recall. If they receive no reports--NOTHING WILL GET DONE. If you didn't report it a year ago...notice that nothing got done?

There is also a search tool on NHTSA's web site, you can search to see if anyone else has reported this, on other models as well.

Since our brake pedals are just pacifiers, I would expect this to be more of another software glitch issue, that can and should be addressed by a software update across the model line.

FWIW a classic description of hydroplaning is that "the brakes just let go" and there was no brake response. After a split second, an ABS system would then kick in resulting in "no brakes" followed by slamming. Could be perfectly normal for a modern car.

Hydroplaning on water feels just like driving on black ice.
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Old 03-16-2015, 10:01 AM   #16
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Coming from the days when disc brakes were a high-end oddity and DRUMS were the norm, I will say that disc brakes "don't" slip in the wet. Compared to the way that drum brakes would and sometimes did stop you on the far side of an intersection after going through a puddle, I would be very curious to actually see an explanation for disc brakes showing any significant "slippage", i.e. for more than one wheel revolution.
But I'll accept anything as possible.

If you are in the US, please contact the national Highway Transportation & Safety Administration at nhtsa.gov and FILE A COMPLAINT. If they receive multiple reports, they can order an investigation and recall. If they receive no reports--NOTHING WILL GET DONE. If you didn't report it a year ago...notice that nothing got done?

There is also a search tool on NHTSA's web site, you can search to see if anyone else has reported this, on other models as well.

Since our brake pedals are just pacifiers, I would expect this to be more of another software glitch issue, that can and should be addressed by a software update across the model line.

FWIW a classic description of hydroplaning is that "the brakes just let go" and there was no brake response. After a split second, an ABS system would then kick in resulting in "no brakes" followed by slamming. Could be perfectly normal for a modern car.

Hydroplaning on water feels just like driving on black ice.
I dont think its hydroplaning. Also I have winters on and it began with summers last year.

I did not think of contacting Transport Canada. But i happen to have a good buddy who works there so ill call and see if anything has been reported. Thanks!
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Old 03-16-2015, 05:05 PM   #17
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Went for a drive tonight and got it to replicate in the wet conditions.

https://www.youtube.com/watch?v=Zxk5...ature=youtu.be
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Old 03-17-2015, 04:23 AM   #18
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Some day take your car out on a dry road and at about 35 mph wack the brake pedal hard and fast, and you will be surprised at the feeling of the car trying to bury itself into the road and stop. It's a great feeling!
I took it out last night to get the above youtube video. I tried what you were stating and the car stops without issue. So much so that at points the tires started screeching. Then it started to rain. I was able to replicate the issue 3 times after some highway driving. Once after going through a large puddle. The issue occurred and ABS also kicked in. Second time was entering the on ramp to return back to my area, occured and no abs. Third time (video) the issue occurred cleanly and no abs activated as well. This is what I've experienced before. During the video, the 'thud' is the release and reactivate of the breaks, and the gforce sensor in my camera actually picks up the change. The mount muffles the cam mic, its even louder in the car.
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Old 03-17-2015, 05:33 AM   #19
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Looks like just a SINGLE pulse of the ABS. You may have been braking over a wet patch which was just enough to cause a wheel to lock up for a split second, causing the ABS to release the brakes, then reapply them once the wheel was turning again.

Note that the ABS does not necessarily continuously pulse the brakes. It just works in a feedback loop. If the wheel does not lock up again, then it will not continue to pulse the brakes.

This could be where you are braking just on the threshold of grip so the wheels may or may not lock up, or the road surface is inconsistent (especially in the wet) so the wheels may lock up in one patch, but not a different area.
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Old 03-17-2015, 06:51 AM   #20
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Hmm, so do you think this is normal? I only question because no one else seems to have experienced this.


I'll upload the video of it happening and the ABS kicking in after, because the sounds/feel are completely different.
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Old 03-17-2015, 06:51 AM
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