EEEK sitting at light, car lurched forward!

Sometimes, when sitting at a light the car will start the ICE to recharge the batteries or to re-heat the catalytic converter / warm the engine and this will cause a noticeable shudder / lurch in the car. There have been a couple of times it was rough enough that I thought I had been bumped by something, but no one was behind me. You normally don't have to press excessively hard on the brake pedal, but you do need to depress it rather firmly to keep from moving.

 

Sounds like everything is normal, including the shutdown shudder.

The lurch is just the car reacting to the ICE being quickly spun up; lots of rotational inertia. So, when stopped be sure to press the brake pedal firmly and when parked with the system on and READY, be sure to engage the parking brake to prevent the car moving an inch or so when the ICE kicks on.

 

This is normal. You should always keep your foot firmly on the brake when you have no intention of moving. This is true with any car.

Tom

 

Doesn't sound 'normal' to me at all

 

But it shouldn't shudder and move like that.

I have noticed that after a minute of driving (depending on the temperature) I get a little surge as I drive, like the choke is reduced when it warms up, if it had a choke. Since this happened a half mile from her home, I wonder if this is what happened, and as she just holding the brake lightly it was enough to overcome the brakes. Still seems like a stronger surge than expected to make it feel like she was hit from behind.

 

Hybrids are a bit different from cars that keep the engine running all the time. Some starts can feel non-linear. The advice in the posts here are important in maintaining safety. They are not any different than safe driving practices in any other car, just a bit more important now. You might also notice that the cruise control responds without hesitation when going uphill. Some people think the car is out of control and accelerating. This is simply the lack of hesitation and instant torque of the electric motors. You will learn what to expect of the car as you drive it more. It doesn't have a "mind of its own" Remember that the ability to move is always there and you should be able to apply firm braking pressure whenever stopped and engage PARK and the parking brake when stopped for more than traffic controls. Adjust the seat so that your foot can be planted flat on the carpet next to the brake pedal. You will grow to love the car once you understand its little quirks.

 

Well, in the spirit of questioning how things work and after researching how the Prius works, I have difficulty understanding the following:

1. If the Prius car is stopped and
2. the ICE is off and
3. the driver selection is in drive "D" then,
The driver should depress the brake harder than they normall would in ICE only car (just in case the ICE in the Prius starts).
This comment is not intended to minimize the safety and advocate against the advice in this thread but to help understand what is normal and why.
I won't go into details in this thread but I think the Toyota PSD design team took the scenario that was first described in this thread into consideration. I will bring this question up in the technology thread.
Thank you.

 

I think I see your problem.

... Brad

 

I'm too new at this to know if what you experienced was beyond the normal range, but it does re-enforce the need for the driver to keep his/her foot on the brake firmly, especially when waiting to turn left. If the guy behind you had bumped the car, or it surged as was described, it could have pushed the car over into traffic if the wheel was turned at all. As with a lot of this stuff, that's true with any car, but more so with Prii.

 

I didn't realize any 2008 were made without a cruise control. I thought after 2001, all Prius came with cruise control.

Bob Wilson

 

It doesn't have to be harder. As the OP pointed out, her foot was not on it very hard - in fact it was so light, that the car was slightly rolling.

As long as your foot is kept on the brake keeping the car from moving, the car won't jump forward like that.

 

Sometimes if I don't push hard enough on the brake at a traffic light I look at the mfd and power is going to the motors even though I'm not moving (especially if the road is uphill)... I don't like that because it's wasting battery power. So, I started pushing harder on the brake. Have not noticed any lunging however. It can be surprising when the ice starts up unexpectedly but I've never had any change in the motion of the car due to that.

 

Startle reflex also, perhaps? The engine starts and you involuntarily jump, releasing what little pressure you did have on the brake pedal?

 

Drivers education taught me to NEVER turn the wheels left until you are ready to turn. This is precisely to avoid this problem of being hit from behind while waiting to turn.

It also taught me to ALWAYS stop with enough space in front you can see the bottom of the tires of the car in front. I often don't follow this rule precisely in high traffic so as to prevent lane cutters from stealing the space in front. YMMV.

 

"Well there's your problem." You need the extra stuff to suppress the lurching, run away Prius problem. No doubt the other run away Prius we've seen reported in the past must have been basic units just like this one. :bolt:


Bob Wilson <grins>

 

Interestingly, my VW Passat does this all the time. I know exactly what you're talking about - and w/ the Passat, it's a known issue with models made before 2004. I can't speak for the Prius, but with the Passat, it has nothing to do with braking (that I'm aware of)... I'm convinced the problem is with the computer that controls the transmission, but of course every time I've brought the car to the dealership, they just say they "can't duplicate the problem" even though a manager told me this issue has been fixed in newer Passats. :mellow:

Fingers crossed this doesn't happen to you again.