Very scary - uncontrollable acceleration in reverse

Maintenance/Repairs
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1

My wife has a 2002 Honda Civic, 55k miles, auto transmission. Today she started it in the garage and put it in reverse (with her foot on the brake). There was lurching so she shifted back to park. She waited briefly then shifted again into reverse with her foot still on the brake. The car immediately shot backwards without warning. She careened down our 60 foot driveway as she was fighting to gain control of the car. The brake felt normal, not sinking to the floor; it just wouldn’t stop the car. She tried to apply the parking brake but it had little effect. When she came to the street she ended up turning 180 degrees and hitting a tree. This stopped the car’s movement, though the front tires were still spinning at high speed against the curb until she turned off the engine.

Naturally we were afraid to drive the car so we called a towing service, which took the car to our local Honda dealer (where all servicing has been done). Though no mechanics were working on Saturday afternoon, the service manager was in. He drove the car in the parking lot and found nothing wrong, though he said he would have to wait until Monday for a full diagnosis.

I have two questions: 1) What happened?; and 2) What questions do I need to ask of the Honda dealer on Monday. After this scary situation, I don’t want to end up with the dealer saying “everything is ok.” Until we have answers, we do not trust the car. Luckily no one was hurt but next time it could be different.

2

The problem might be with the idle air control circuit. This is what controls the engine idle speed anytime the accelerator isn’t being used.

I had a coworker that had the Idle Air Control valve go to the wrong position. Only in their case, they were pulling into a gas station. And when the IAC valve went to the wrong position, the vehicle took out two gas pumps.

Tester

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3

You haven’t given us enough information, although you tried.

What was the engine speed when all of this was happening? Was it a normal start-up speed, or was it abnormally high? Unless we know these things, and possibly more, we can only guess.

Here’s what you don’t want to hear:

A car’s brakes can always overpower the engine. This has been proven with many cars, even very powerful cars at full throttle. The brakes always win. Eventually.

So, if your wife had pushed hard enough on the brake pedal she could have stopped the car, or at least slowed its progress significantly, regardless of engine speed or the gear in which the transmission was.

I don’t expect you or her to believe me, but it’s true.

The parking brake was a good idea, but it won’t stop the car. It’s just for parking. I think she wasted time on the parking brake when she should have been pushing harder on the regular brake pedal.

I’ll bet the dealer will say, “We couldn’t find anything wrong,” and I’ll also bet there isn’t anything wrong.

What happened was your wife pressed the wrong pedal, which is what usually happens in these cases.

You, and she, will swear otherwise. Be that as it may. The odds of the car being at fault are astronomical. Sad, but true.

Even the recent Toyota “unintended acceleration” problems, now that they’ve been investigated, have turned out to be driver error.

This isn’t making you feel any better, is it?

I already know the answer.

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I’m in agreement that an Idle Air Valve can cause high RPMs and also in total agreeement with mcparadise’s comments about this being driver error.

5

I’m not going with driver error and I don’t think for a minute that anything was established regarding the Toyota issues. The problem with the Toyota “investigation” that is also present in Mcparadise’s statement of “what usually happens in these cases” is that the “investigations” look for an alternative cause. If they don’t find one then “driver error” is the conclusion. Well, that doesn’t actually establish anything at all. It comes out of completely faulty logic and confirms nothing at all. This is like a shop not finding a cause for an intermittent no-start condition and concluding that the driver is sometimes forgetting to turn the key.

I’m also not saying that people don’t make mistakes and that there is no such thing as a case of “unintended acceleration” that isn’t from driver error. Its just that no one actually knows what “usually” happens in these situations.

I would just wait to hear back from the shop - but I certainly agree with mcparadise that you shouldn’t be surprised if you hear that they couldn’t find anything wrong.

6

Thank you all for your thoughts. I will keep these in mind when I talk with the Honda service people on Monday. And I will post the results here. (I hate it when people raise a question on this kind of forum and never report back what the result of the testing was.)

I am not automatically discounting mcparadise’s comments about driver error but perhaps I didn’t share enough detail to rule this out. When this acceleration was happening I saw it all from my kitchen window. When my wife spun around and hit the tree I ran out to see if she was ok. I observed the car wedged against the tree with the front tires still spinning fast against the concrete curbs. The engine was racing so I told my wife to turn off the engine. As she did so she kept her right foot tightly on the brake. Only when the engine was off did she raise her foot from the brake. Then, wondering if the brakes were bad, she immediately lowered her foot in the same place to see if the pedal would sink (it didn’t). So the sequence was: 1) foot on brake; 2) turn off engine; 3) raise foot; and 4) almost immediately lower foot in the same place. It light of this, I’m not sure how operator error could have taken place.

I do not want to become defensive because I truly am grateful for your advice. I just don’t see how operator error correlates with my observations in the preceding paragraph.

7

The point made about brakes overpowering the engine is due to the fact that the torque converter on an automatic transmission car will override the engine.

If you want to test this when you get your car back try the following. Hold the foot brake down, shift the transmission into reverse, and then try to rev the engine quickly.
The car should not move and you will feel the engine stall. (The converter stall occurs at various RPMs depending the car, etc but generally anywhere from 1800 to 2500.)

8

Odds are, the dealer service department will not be able to find anything wrong. If that is the case and the car genuinely cannot be trusted after this event, it will need to be replaced with a car that can be trusted. If your conscience will allow it, it can be sold to somebody else. If there is real concern that it could happen again, the car should be destroyed. Bear in mind, though, that many of the Toyota vehicles that had “unintended acceleration” events that occurred after the initial ones made headlines and became a media sensation were sold by their owners and have had no subsequent occurrences to date.

The most common driver error that causes this type of thing to occur is having one’s foot half on the brake, half on the gas. This often leads to a description of “the harder I pushed the brakes, the faster the car went”, which may very well be what happened in this case. Something as simple as a new pair of shoes can dramatically increase the likelihood of this driver error occurring. Improperly adjusted (if drum) or worn brakes can also cause the brake pedal to be low enough to put it close enough in height to the accelerator, allowing both pedals to be pressed at the same time if the driver’s foot is hanging off the right side of the brake pedal.

I also wanted to reiterate mcparadise’s comment on the fact that brakes will always overpower the engine. Think of it like this: if a car can accelerate from zero to 60 mph in six seconds, it is generally regarded as quite impressive performance. Now imagine if the same vehicle’s brake system were not capable of generating that kind of power, and at it’s maximum capabilities, took seven seconds to slow from 60 to zero. It would be an absolute deathtrap. If brake system’s ability to perform work were translated into horsepower, most average vehicles would have their brake performance numbers into the four digit zone. Even the biggest, baddest diesel pickup truck can’t outmuscle it’s brake system with it’s engine, let alone a little Civic with just over 100 horsepower.

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I do not want to become defensive because I truly am grateful for your advice. I just don’t see how operator error correlates with my observations in the preceding paragraph.

But that would be consistent with her foot being on both the brake and the gas at the same time. And lifting and resting your foot it will be hard to tell that you are putting it exactly where you lifted it from.

10

Just an objective observation here. In my experience it has most often appeared that unintended acceleration has been the result of driver error. Especially when the unintended acceleration resulted in the vehicle operating in an out of control situation for more than a few seconds. I don’t wish to sound accusatory or make light of the situation but a driver who becomes overwhelmed and panicked in such a situation is unlikely to be fully aware of their own actions. But!!! I have driven several cars with “fly by wire” throttles that tend to feel out of sync. Pressing the pedal 1/4 of its travel might result in very limited response but pressing the next 1/4 of travel results in a great deal of acceleration.

11

If your right foot is slightly to the right of where you think it is, your left foot will be also. This will put tour left foot under the brake pedal and with your right foot partially on the gas you will not actually be applying the brake at all. This is very disorientating and it is no wonder the driver doesn’t know what happened. This is similar to the feeling you get if you are backing into a parking space and the car next to you starts pulling out. If you didn’t realize someone was in that car, you will be mashing your brake pedal when you are actually stopped but thinking briefly and your brakes are not working. that you are shooting backward

12

As everyone expected, the Honda dealer could find nothing wrong. I do appreciate the comments, especially from mark9207 and oldtimer11, each of whom explained in some detail how the driver error could have taken place. This is especially useful in understanding my wife’s case because she has no feeling in her feet due to diabetic neuropathy. If that isn’t enough of a burden, she needs to wear extra wide shoes. So it is likely she was stepping on both the brake and the accelerator.

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Did this ever occur to your car again? And if yes, what did you do to resolve the issue if any? I have a 96 Altima with a 4 speed automatic transmission that has the same problem. It’s not often but every once in a while I will put the vehicle in reverse WHILE I AM BRAKING, and the engine will rev extremely high and will take off if I let go of the brake. I have to put it back in park and back in reverse again to solve it. The A/T fluid is full. When I do put it in reverse and it doesn’t rev extremely high I must gently as possible press the gas because pressing it with any moderate pressure will cause it also. Please do not bother responding if you’re going to tell me it’s driver error, because it’s not. I drive my other car every day to work and this issue has never happened. Only my Altima and I am positive I know the difference between a gas and brake pedal so post your sarcastic comments elsewhere. This is an actual problem I need help with before I waste money I don’t have. Thank you.

14

It is a good reminder that in a situation such as this one can turn the car off and hopefully void collision damage.

15

see @Tester’s comments above about the idle air control circuit.

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I don’t know if this car is fly by wire.
In older RWD vehicles with mechanical accelerator linkage a broken motor mount can cause this problem. Scared the h out of me. Both feet on the brake pedal, rear tires churning smoke, front wheels locked. Had to turn off ignition.

17

There’s the key phrase right there as pertains to OP. If you let go of the brake. Don’t let go of the brake and you’ll be fine :wink:

Your era of Altimas are known for their mass air sensors causing problems, ranging from stalling to RPM surging. I’d be looking there in your case.

BTW, best practice is to start a new thread when you have a question - a lot of people will ignore a thread that’s 6 years old.

18

When throttles were controlled by rods several models were known to suddenly open the throttles to wide open when a motor mount broke and the driver accelerated enough to lift the engine off the broken mount. I have had that occur while driving several of the older cars most notably an old Camaro which had enough horse power to begin to fishtail pulling away from a red light. Braking would not stop the car. Turning off the key was the only safe option. But regardless of how the throttle is actuated turning the key off will certainly end the acceleration and in many situations it’s still the best option.

19

Had this problem on two cars. My dads 289 Studebaker, but that was a stick so press in the clutch and engine would settle back down.
My Pontiac, automatic, yup turn off only solution.

21

The solution to unintended acceleration, in the emergency moment, is put it into N (neutral). Any automatic I know of required only a shove to move the lever from drive or reverse to neutral. If you shut off the ignition you lose the power steering and the brake assist, which can lead to loss of control for a driver not prepared to cope with that.

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