2010 Prius Brake problem not resolved even after dealer correction

Hi Tom,

Is this the remaining NHW20 braking pause or delay?

Bob Wilson

 

None.

No suggestions, just facts and data. What protocol replicates your symptom(s)?

Bob Wilson

 

I assume no delay in the NHW20 either? You obtained a result inconsistent with the widely-documented delay (whether real or perceived) in the Gen 2 reported by owners here and elsewhere. This suggests either your methodologies/equipments are not sensitive enough to detect this delay or it's a perceived, psychologically-based delay as a result of a disconnection between the driver's expectation and pedal feel/sensitivity during the transition. If it's the latter, it means the car doesn't actually accelerate during the transition, which has actually been suggested by several forum members here.

 

Bob, I'm not sure I understand your question. Are you asking if I meant "pause" or "delay", or are you questioning whether it still remains?

Tom

 

From the survey we did back in January, a similar brake anomaly was acknowledged for the NHW20 but apparently was not as severe. So I'm wondering if folks are describing the NHW20 problem and your profile still shows an NHW20 model.

Since I've gotten SSC-A0B, I've not been able to replicate the brake-pause. In contrast, I'm not having any luck finding a description of a protocol to find any remaining brake pause in the ZVW30. Existing data doesn't show a problem.

Bob Wilson

 

Data are only as good as their collection methods and interpretations. You still haven't confirmed whether your methodologies are sensitive enough to detect a delay less than the claimed ~600 ms or considered the possibility that the short-lasting delay doesn't necessarily result in any real change in acceleration/deceleration (and may be mostly perceived from the driver's perspective, e.g. Blind Guy didn't feel anything while his wife detected the delay even in their Gen 3 pre-SSC-A0B ).

 

We haven't had any problems with our 2010 Prius.

 

I can't answer the poll. When I first had the car, I barely noticed it until one day when I went over a real rough patch in the road. Did not get the feeling too much until winter when the roads became more bumpy and the plows left lots of potholes.

After the fix, I would not say it is totally resolved, and I do not have the same problem. It's just very slight and definitely not as scary as it was before the patch.

 

Yes. For me it's still the NHW20.

Tom

 

I am sympathetic to your data request so attached is the raw data from the accelerometer.

I look forward to seeing your data. You do have some, right?

Bob Wilson

 

I first noticed this issue back in the early winter, November 2009, on my 2010 Prius. I would hit this little hill on my street and the car would go airborne (not enough for the wheels to go in the air)... but I would notice for a split second - NO BRAKES. Scary. But before you have a heart attack the brakes would kick in. So I had the recall service done.... Yesterday I was driving on an extremely pot holed country road in the rain, and when I started hitting a bunch of potholes I hit the brakes and they were working fine and then Wth all of a sudden, with my feet hard on the brakes there were NO BRAKES at ALL. This happened long enough for me to totally freak out this time. THAT WAS scary. I had a 2007 Prius and never once encountered this sort of thing. I view this as unacceptable vehicle behaviour. I have my foot on the brakes, I'm lurched forward and then it felt like the car accelerated (it didn't accelerate, I did not hear the engine rev up, the brakes just let go completely). However, I still love my Prius. I want to add that in this no brake scenario, it only lasted - I don't know, 300 msec's does sound about right. But it is a very nervous 300 msecs if that is the time frame. Feels like 2 seconds. But probably 300 msecs.

 

Where? Do you have or can you get a photo of the road? Kilometers per hour?

Bob Wilson

 

I didn't request any data from you, nor do I have any. I'm just pointing out that for the data to mean anything, you'd have to ensure that the accelerometer is sensitive enough to detect less than ~600 ms delay and if so, you have to consider the possibility that the <~600 ms delay doesn't necessarily result in any change in acceleration/deceleration and may be a perceived phenomenon on the driver's part. Otherwise, any data interpretations are flawed.

 

Embedded in the data is the calibration information and contact for Gulf Coast Data Concepts. One would only have to open the file.

If you'd like to test the unit, send me an instrument deposit, $100, for the X6-2 and I'll ship it to you. I have no problem if you would like to check the instrument calibration.

Bob Wilson

 

If you think it's possible that there's no change in the acceleration of the vehicle (positive or negative), then just what do you think the driver is perceiving?

 

Thanks for the offer, but lets focus on the data you've already accumulated. Don't you think it's interesting that you've detected absolutely no delay with your accelerometer when many, many Gen 2 owners have reported a very brief "surging forward" during the transition between regen and friction braking? It suggests either the accelerometer is not sensitive enough to detect this short-lasting delay (which is entirely separate from how well it is calibrated) or it's a perceived phenomenon on the driver's part.

A disconnection between the driver's expectation and pedal feel/sensitivity, which can play a trick on the mind. Suppose you're in a car thinking the engine is on (but it's not actually on) and step on the gas pedal, your body/head will naturally lean forward expecting the car to go. Same concept.

Passengers (particularly our fellow member, Blind Guy) have claimed not to detect anything while the driver of the car thought it surged forward when braking over potholes. Strongly suggests it is psychological.

 

It was out on a country road near Beaverton, the potholes were insane and a very rare road condition. I was doing about 70 km an hour which I shouldn't have been doing. They weren't huge potholes, just tons of small ones. And I mean tons... the car was getting hammered.

This was no illusion either, the brakes completely let go while I travelled a good 10 feet I'm guessing. My heart raced when it happened. I've never owned a car that brakes like this and I've owned a lot of cars.

 

It means my data is for the ZVW30, 1.8L Prius, not the 1.5L, NHW20. I've asked but so far not found anyone with an NHW20 willing to use my second accelerometer to document the problem. I had one local offer but like me, he is pretty busy.

I have two accelerometers and the second one, X6-1A, I don't mind loaning out to any NHW20 owner committed to documenting and resolving this problem. The prerequisites:

1. Documenting where problem can be recreated.
2. Ability to recreate problem at will. This may require special weather or other circumstances but knowing the exact circumstances is critical.
3. Sharing these details!

The earlier survey reported a significant number of 1.5L NHW20 owners had experienced the brake anomaly. I'm happy to help document the problem by loaning an accelerometer but I don't have a NHW20 to test. I do have a 1.5L NHW11 but this is a different model and I've not been able to replicate the problem with it.

Fortunately, we may have discovered a way to escalate the problem. But to have an effect, we need an accurate, well documented problem with credible engineering data. I can help on the engineering data but don't have a 1.5L NHW20 test article.

Bob Wilson

 

Excellent, I'm getting a better picture:

Could you use Google Map or Google Earth and post a link or the latitude and longitude? Sometimes we can get a Google Street View that can help.

We have some 'less affluent' counties in North Alabama whose road repairs have not been very good. I'll ask around and see if I can find something that matches your description. There may be some unpaved roads matching your description.

Understand I'm out to document problems with engineering data. If I can get enough information I may find a way to replicate the problem.

Thanks,
Bob Wilson

 

The area is near Beaverton Ontario, as below, however you can't see it in google maps at street view because it is a remote road. A bridge is under repair, and they detour traffic down a country road that is made of dirt. So the unusual high traffic and rains have created a barrage of potholes. As I said, it's a pretty unusual circumstance and I don't know if it lasts long enough that it would cause an accident and I haven't tried to replicate the event, not that I want to. Priuschat won't let me add the full google maps URL so you'll need to paste this after the standard URL,


/?ie=UTF8&ll=44.434102,-79.08518&spn=0,0.016469&t=h&z=17&layer=c&cbll=44.433246,-79.086069&panoid=Tvs3Tub4sPk1OCSAfYZpYg&cbp=12,138.57,,0,7.52