Rx400 Speed Up During Slow Down

[LittleSand]

Hi,

I have couple questions due to the current recall and would like to have some confirmation. I don't know much about car. So an insight knowlege are apprecated. I have the 2009 RX400 and here is my 2 questions.

1) When I am driving at a speed that is not too fast, like under 60 KM, I notice when I start braking, it speed up a little bit. All this time, I was thinking it is because the transmission is disengaged and put into netural, so the car speed up a little due to no engine load. It is similar to when I manually shift a non-hybrid car into neutral, it speed up a little. At least it feel that way. Is it a problem or is it normal with the RX400? Are all other owners have a similar experience?

2) I read other article, they mention to shift the gear into netural to control the unintend speed up. So my question is, is the shift mechanical or eletronic control? Since the shifting is just a tap, I feel it is more like an electronic control or at least semi control by electronic. Is it? Any advise of what to do if for some reason we can't shift? I know it is kind of very very low probability, but it is still kind of worry and not getting a peace of mind.

Thanks,

[Jim Clark]

Hi,

I have couple questions due to the current recall and would like to have some confirmation. I don't know much about car. So an insight knowlege are apprecated. I have the 2009 RX400 and here is my 2 questions.

1) When I am driving at a speed that is not too fast, like under 60 KM, I notice when I start braking, it speed up a little bit. All this time, I was thinking it is because the transmission is disengaged and put into netural, so the car speed up a little due to no engine load. It is similar to when I manually shift a non-hybrid car into neutral, it speed up a little. At least it feel that way. Is it a problem or is it normal with the RX400? Are all other owners have a similar experience?

2) I read other article, they mention to shift the gear into netural to control the unintend speed up. So my question is, is the shift mechanical or eletronic control? Since the shifting is just a tap, I feel it is more like an electronic control or at least semi control by electronic. Is it? Any advise of what to do if for some reason we can't shift? I know it is kind of very very low probability, but it is still kind of worry and not getting a peace of mind.

Thanks,

Do people in Ottawa speak English?

[cduluk]

There's no such thing as a 2009 Rx400h

[LittleSand]

There's no such thing as a 2009 Rx400h

You are correct. Brought it in 2009 and always thinking it is a 2009. It is a 2008.

[LittleSand]

Do people in Ottawa speak English?

Thanks for you comment. And exactly which part of my question you don't understand?

I suggest you add an auto grammar corrector and spell check in all the forum site. It will add a few billion dollars in your current income.

:o

[lemon]

Hi,

I have couple questions due to the current recall and would like to have some confirmation. I don't know much about car. So an insight knowlege are apprecated. I have the 2009 RX400 and here is my 2 questions.

1) When I am driving at a speed that is not too fast, like under 60 KM, I notice when I start braking, it speed up a little bit. All this time, I was thinking it is because the transmission is disengaged and put into netural, so the car speed up a little due to no engine load. It is similar to when I manually shift a non-hybrid car into neutral, it speed up a little. At least it feel that way. Is it a problem or is it normal with the RX400? Are all other owners have a similar experience?

2) I read other article, they mention to shift the gear into netural to control the unintend speed up. So my question is, is the shift mechanical or eletronic control? Since the shifting is just a tap, I feel it is more like an electronic control or at least semi control by electronic. Is it? Any advise of what to do if for some reason we can't shift? I know it is kind of very very low probability, but it is still kind of worry and not getting a peace of mind.

Thanks,

Do people in Ottawa speak English?

Actually a fair number speak French as a first language and English as a second language, or are quite comfortable with either.

When someone who speaks Spanish (which seems to be the second language in the U.S.), posts a semi-understandable question on here (which I've seen) I bet not many Canadians ask if the original poster can speak English. What was the point to your post, since it obviously didn't answer either of the questions.

[SW03ES]

Are you certain that the vehicle ACTUALLY speeds up, or does it just feel that way?

[LittleSand]

Are you certain that the vehicle ACTUALLY speeds up, or does it just feel that way?

I am not certain if it actually speed up. But if I have to pick a choice. I say Yes, it speed up.

It is same as or feel as I press the clutch of a standard transmission car and shift into netural. The car go a bit faster as the wheel is not engaged to the transmission/engine. But I am not sure about the RX400. It doesn't happened to my other auto transmission cars. That is why I asked. In fact, it happens more often than when it was brand new (20,000 KM now). I say, it happens over 50% of time when I brake under slow speed condition, especially when I easy on the brake at first.

Thanks,

[bainzey]

Hi,

I have couple questions due to the current recall and would like to have some confirmation. I don't know much about car. So an insight knowlege are apprecated. I have the 2009 RX400 and here is my 2 questions.

1) When I am driving at a speed that is not too fast, like under 60 KM, I notice when I start braking, it speed up a little bit. All this time, I was thinking it is because the transmission is disengaged and put into netural, so the car speed up a little due to no engine load. It is similar to when I manually shift a non-hybrid car into neutral, it speed up a little. At least it feel that way. Is it a problem or is it normal with the RX400? Are all other owners have a similar experience?

2) I read other article, they mention to shift the gear into netural to control the unintend speed up. So my question is, is the shift mechanical or eletronic control? Since the shifting is just a tap, I feel it is more like an electronic control or at least semi control by electronic. Is it? Any advise of what to do if for some reason we can't shift? I know it is kind of very very low probability, but it is still kind of worry and not getting a peace of mind.

Thanks,

Do people in Ottawa speak English?

Actually a fair number speak French as a first language and English as a second language, or are quite comfortable with either.

When someone who speaks Spanish (which seems to be the second language in the U.S.), posts a semi-understandable question on here (which I've seen) I bet not many Canadians ask if the original poster can speak English. What was the point to your post, since it obviously didn't answer either of the questions.

Ditto... I was able to understand his post just fine. And yes there was some grammatical type errors, but clearly the guy tried his best to explain his concerns and situation. Last I checked this is a LEXUS OWNERS CLUB... Where we try to share knowlage, not a "Hey buddy, lets slam you cuz apparently you may not speak English as your first language..." club.

Whatever man.

[skyfish400h]

I think a better understanding of physics will help in discussing the braking behavior of hybrid vehicles.

It may subjectively feel like the car is speeding up or "surging" as you decelerate because of changes in the rate of deceleration. Much like you feel "weightless" when you drive over a rise in the roadway at high speed. You are not actually rising out of you seat, you are just feeling lighter in your seat, if that makes sense. If you were to actually go into negative g's the only thing holding you in your seat would be your seat belt. I doubt many of us have ever experienced that unless we were in an accident or we drive our cars like we stole them ;)

So for braking: The car is not speeding up, it is just not stopping as fast as your brain and inner ear tell you it should be based on what it was doing just a split second before that.

We have all become accustomed to steady brake pedal pressure translating directly into steady deceleration. When our vehicle's rate is managed by a computer and it has more than one system contributing to the overall rate, then changes that may occure during the hand off between one system and another may have our brain and inner ear fooled into thinking something is wrong when it isn't.

Normally this would be a good driver instinct to have because it makes you sensitive to changes in the braking behavior that may actually be a problem such as fading brakes, wet drums, loss of boost, or loss of traction... but in the case of these hybrid vehicles this instinct leads to the perception that the car is not stopping well and can be alarming when you experience it for the first time.

I say practice driving your hybrid vehicle in a wide variety of conditions so you can re-program what is now the new normal for braking behavior (and what is not, like losing traction and having the ABS kick in).

There may be technological fixes coming that can smooth the experience back out again and restore our gut confidence in "steady pressure = even deceleration", but until then we have to live with what we've got.

[SW03ES]

My guess is skyfish's explanation is pretty on the nose...

[katzjamr]

Little sand i agree with skyfish400h answer and only would like to add, as you may have noticed these vehicles coast really well, so there is no feeling of slowing like in a non hybrid car where coasting alone will slow the car without braking.

[400h08]

I have to say that I have never experienced this feeling when traveling at 60km.h or under. I suggest you have it checked out by your dealer since it is still under warranty. The only surging forward feel I have is at very slow speed (under 10 km.h) going over a slight bump.

[RXREY]

I agree about the grammar, the person was trying to ask a question...that being said, I did suggest to another forum member that he should pay more attention in his English class. I was sarcastic with this person because he a was smug 16 year old and came off as an engineering genius. Other than that, I would not feel comfortable being unkind. I came from another country and had to learn English so I am sensitive to the fact that not everyone speaks English or writes it perfectly. In this forum we have many members from other countries and deserve respect and an understanding answer...just my $.02.

Anyway, I hope whatever is going on with this person's RX400h gets resolved by Lexus. I know that my 06 felt different when I first drove around...the brakes didn't seem to work...now I don't feel a thing. I got used to whatever the issue was. It turned out that the regenerative braking simply feels different. Rey in L.A. and proud American

[mk0099]

Thanks all for the detailed clarification. I just would like to add that this behavior might occur when slightly pressing the brake pedal. Try pressing it more firmly (maybe half way or something like this) at 30 or 40 Km and see if the car accelerates. It should not.... which means it's just the braking experience.

In all cases, if you are not comfortable with the brakes, you can check with the dealership.

P.S: execuse me if my posts include any language errors...