My wife was driving at 40 mph when the engine suddenly begain to over-rev, causing her to nearly lose control. The car quickly accelerated to 60 mph. All this happened on a state hwy which had several "S" curves going downhill.

She was unable to shut engine down using either the power-button, nor could she shift out of drive.

Finally, after the road flattened out, she was able to bring the car to a stop. However, the hard braking resulted in a left, front disk brake fire. The fire was put out by a man who was alongside the road. He was able to run to his house for 2 fire extinguishers.

The event occured on Wisconsin state route 107, approximately 1 mile south of county route J, in the early afternoon. The temperature was approximately 80-85 degrees F.

A short time after the incident, I wanted to test the emergency brake, so I set the emergency, started the car, placed it in Drive, and pushed the accelerator to the floor. All seemed normal.

The Prius was towed to Rosemurgy Toyota in Wausau, Wi.

To date, service is not complete.

However, this is Toyota's explanation:

The Toyota rubber floor mat was against/over/on the accelerator, causing it to be pushed down (here, I was shown a picture which purports to show this).

But, note what I did when I got into the car: I set the brake, pushed the Power Button (engine did not suddenly rev) and I shifted into Drive (could I do that with a reving engine)? Lastly, I pushed down on the accelerator peddle!

There was at least one other incident reported on an '05. Toyota states that what occured on Monday, June 25, 2007 to my '06 Prius had never happened before.

 

Hi,

My 2003 Prius is the earlier version but I will try to replicate this problem later:

1) accelerator fully to the floor
2) shift (manual control, not a button) to "N"

I have shifted to "N" while in a hill climb with a significant throttle and not had a problem. The engine briefly revs. However, I will have my Graham scanner recording the data to see what happens.

If I can 'rent' an NHW20 Prius, I'll try to replicate the problem in the rental. I have heard the 'floor mat' theory before.

Body damage from the fire? Any photos?

Bob Wilson

 

Centrider, that must have been terrifying and I am very glad it did not turn out worse. It may be hard for both of you to drive the car with confidence after that.

There have been some number of 'rug in a bunch' accelerations, but I have not heard of other (say, computer-related) causes. One might speculate about problems in the motor-driven throttle butterfly, but it will be most important to hear their final analysis of the problem, and what parts are replaced.

I would expect new brake hardware and tire on the 'fire side' and perhaps new brake fluid as well. All of that secondary to the cause, of course.

It is hard to forgive the 'never before' stance. Feel your pain there too. I understand that they have 'cover the a$$' legalistic reasons for lying (more or less) in response to your question. Certainly not trying to forgive them, but I guess I know why this would be the standard reply to such difficult questions.

Bob's rental of an NHW20 would certainly be helpful in understanding the 'rug in a bunch'. But not if there is some unique problem with your car. Good luck with this.

DAS

PS: I did not write a$$ initially but the nanny replaced my letters with ***. Interesting.

 

Thanks for your response. Not to discourage you, of course, but rather to crystalize my thinking, and to move it from the event forward.

Sooo. According to Nancy (my wife) the car quickly accelerated from 40 to 60. She could not stop the car with the brakes (hence the brake fire). Some of that might have resulted from the car driving downhill (surrounded by lots of cyclist).

I should think the first thought would be to stop the car with the brakes. She usually does not drive the Prius, and so she ignores much of what is displayed.

Possibly she next tried to shift out of D. And than tried to shut off the engine.

I was, floored (no pun intended) when the service manager showed me a picture of the rubber Toyota Prius mat against/over the edge of the accelerator peddle. I moved the mat back(it was not against the peddle when we looked at it yesterday) to its original position. To move that mat, you'd have to move it by hand. And at that, it was difficult to do.

I read the other incident. Much harder to brush off.

No damage to the fender/paint. They're replacing everything in the front brakes. 1500.00 bucks. Some of which are on order.

My guess is that they will say as little as possible. I was told that, as luck would have it, a factory rep was passing through and tested the system and found only that drat floor mat to be the cause.

My guess is that one would need to have equipment in place to capture what I would consider to be a random event.

Thanks for your concern. We are, of course reporting the incident to the NHSTA.

 

Hi,
An engineer, one incident is a 'random event' but this is the second one in one year and that crosses my threshold for 'random.' I want to know if nothing else for my own peace of mind.

The floor mat on my 2003, NHW11 Prius has some 'hooks' that are supposed to hold the floor mats. Yet I've noticed the mats often shift about as if the hooks don't work. To me, this suggests something isn't quite right.

What I'm most concerned about is what it takes to shutdown an NHW20 Prius with the accelerator floored. I don't need to do the 'brake' deal but I want to know if there is some 'complex' operation needed to get the car out of 'max acceleration' mode. So now I'm shopping for a rental, NHW20 Prius.

Bob Wilson

 

Sorry I didn't get around to this sooner, but I'm on the road, so to speak.

Of course you realize we're not talking about a, rug/carpet, but Toyota's own rubber all weather mat. My wife, at 5'1" or so is not able to move that mat with her feet, mat anchored or not.

Because I'm paying for all this, I guess I'll have to replace the tire. I assume (I'll know when I get the car tomorrow) all things associated with the brake fire will be taken care of.

I, like you am interested in Bob's research.

Don't know who reads our offerings, but I've had the same sort of thing happen to me. At first I thought it was me. No, it's our, as you put it, "Nanny".

Thanks again for your concern.

 

I got my car back today and just got back from looking at Toyota's assumption that a rubber floor mat designed by Toyota for the Prius was moved sufficiently such that it was able to contact the gas peddle, depress it and cause the acceleration which resulted in the left front brake bursting in flames.

1) It didn't happen because, well it couldn't. The mat is heavy and stiff enough (with all them little fingers on the underside to dig into the installed carpet) that we could not slide it forward. Besides the design of the mat fits around the foot rest which also blocks it movement.

2) To recreate what Toyota created, i.e., the mat over the gas peddle, as I recall the lower margin of the peddle, I moved the mat by picking it up and placing it on the peddle.

The peddle did not move. It was not depressed at all by the mat. Further, I pushed down on the peddle with the mat in the position shown by the Toyota photo, the mat dropped off the peddle.

I went even futher by placing the mat over the peddle. The peddle, was not depressed by the mat. Placing my foot on the mat/peddle, and then releasing the peddle with my foot, caused the peddle to return to its neutral position.

Finally, I tried all of the above with the engine on (as well, the emergency brake) and ran the test again. The engine failed to race with Toyota rubber mat on the peddle.

I had my wife depress the peddle/mat, and than release them. The accelerator returned to its neutral position.

Anyone owning a Prius with Prius rubber mats can (in fact, I urge you to) try these series of tests.

 

Hi,

This weekend I'll check around N. Alabama and see if I can find the nearest Prius rental. I need some 'seat time' to replicate this problem. (YIPPIEEE!!! I didn't know it could go THIS FAST!!!!)

Bob Wilson

 

"1) It didn't happen because, well it couldn't. The mat is heavy and stiff enough (with all them little fingers on the underside to dig into the installed carpet) that we could not slide it forward. Besides the design of the mat fits around the foot rest which also blocks it movement."

I was actually able to replicate this problem this week. The mat itself is incappable to go over the gas pedal off course. This problem happen by a combination of two things, rubber mat missplacement and floored gas pedal. When the mat shifts its position from getting in and out of the car (notice it's half a persons body weight at least and moving sideways) it can go into a possition where if you depress the accelerator all the way, it will will hold the pedal stuck. A side movement pulling the pedal upwards with the foot should take care of this. Heck I even took pictures with my cell phone for I was able to replicate it three time on my 10 miles commute to work. Then again, P&G techniques develope sensitive feet!
I would suggest all drivers with all weather mats from Toyota to anchor them by using the holes both on the mats and the car. Just do it with something that can be easily removed for cleaning purposes.

 

Thanks for the research.

If I understand it, you were actually able to move the mat into position so that when it the accelerator was floored, the mat caught the peddle? Was the all weather mat over the installed carpet? And was the carpet anchored (but not the all weather mat)?

My wife was driving in a cloud of bicyclist who pretty much dominated the county road, so it was unlikely she floored the accelerator.

And, assuming the mat was over the gas peddle after she finally brought the car to a stop, and shut it down, why didn't it (the engine) immediately begin to race when I started it and put it in gear? In fact, I had to depress the accelerator in order to test the brakes. If the mat was the culprit, than the car should have taken off again.

We too tried to move that mat. My 5 foot plus wife tried, and I tried. We kicked it. We shoved it. and finally we placed the mat over the peddle.

I finally removed the carpet and anchored the mat. A friend who does some-times contract work for Toy started to freak out when I told her what happened and, after she checked with people she knew at Toy (only way that could happen was mat wasn't anchored, blah, blah, blah. . . ) Yeah, right.

Thanks again. Fortunately, our insurance did cover the damage/repair bill, bless their hearts.